Airworthiness Directives; the Boeing Company Airplanes, 9400-9414 [2015-03540]
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Federal Register / Vol. 80, No. 35 / Monday, February 23, 2015 / Proposed Rules
On
December 19, 2014, DOE published in
the Federal Register a notice of
proposed rulemaking (NOPR) to update
the energy conservation standards for
residential dishwashers. 79 FR 76142 .
In the NOPR, DOE invited written
submission of public comments, to be
received by February 17, 2015. On an
email dated January 16, 2015, the
Association for Home Appliance
Manufacturers (AHAM) requested an
extension of the public comment period
by 60 days. AHAM stated in its request
that AHAM required additional time to
review the published analysis in order
to prepare and submit comments
accordingly. DOE has determined that
extending the comment period to allow
additional time for interested parties to
submit comments is appropriate based
on the foregoing reason. DOE believes
an additional 30-days, providing a total
comment period of 90 days, allows
sufficient time for submitting inputs
regarding DOE’s analysis. Accordingly,
DOE will consider any comments
received by midnight of March 25, 2015,
and deems any comments received by
that time to be timely submitted.
SUPPLEMENTARY INFORMATION:
Issued in Washington, DC, on February 12,
2015.
Kathleen B. Hogan,
Deputy Assistant Secretary for Energy
Efficiency, Energy Efficiency and Renewable
Energy.
[FR Doc. 2015–03599 Filed 2–20–15; 8:45 am]
BILLING CODE 6450–01–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2012–0187; Directorate
Identifier 2011–NM–094–AD]
RIN 2120–AA64
Airworthiness Directives; the Boeing
Company Airplanes
Federal Aviation
Administration (FAA), DOT.
ACTION: Supplemental notice of
proposed rulemaking (NPRM);
reopening of comment period.
AGENCY:
We are revising an earlier
proposed airworthiness directive (AD)
for certain The Boeing Company Model
757 airplanes. The NPRM proposed to
require modifying the fuel quantity
indication system (FQIS) wiring or fuel
tank systems to prevent development of
an ignition source inside the center fuel
tank. The NPRM was prompted by fuel
system reviews conducted by the
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SUMMARY:
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manufacturer. This action revises the
NPRM by revising the applicability,
including optional actions for cargo
airplanes, and extending the compliance
time. We are proposing this
supplemental NPRM (SNPRM) to
prevent ignition sources inside the
center fuel tank, which, in combination
with flammable fuel vapors, could result
in fuel tank explosions and consequent
loss of the airplane. Since these actions
significantly change the corrective
action options for cargo airplanes
relative to the proposal in the NPRM,
and because the cost estimate is
significantly revised, we are reopening
the comment period to allow the public
the chance to comment on these
proposed changes.
DATES: We must receive comments on
this SNPRM by April 24, 2015.
ADDRESSES: You may send comments,
using the procedures found in 14 CFR
11.43 and 11.45, by any of the following
methods:
• Federal eRulemaking Portal: Go to
https://www.regulations.gov. Follow the
instructions for submitting comments.
• Fax: 202–493–2251.
• Mail: U.S. Department of
Transportation, Docket Operations, M–
30, West Building Ground Floor, Room
W12–140, 1200 New Jersey Avenue SE.,
Washington, DC 20590.
• Hand Delivery: U.S. Department of
Transportation, Docket Operations, M–
30, West Building Ground Floor, Room
W12–140, 1200 New Jersey Avenue SE.,
Washington, DC 20590, between 9 a.m.
and 5 p.m., Monday through Friday,
except Federal holidays.
For service information identified in
this AD, contact Boeing Commercial
Airplanes, Attention: Data & Services
Management, P. O. Box 3707, MC 2H–
65, Seattle, WA 98124–2207; telephone
206–544–5000, extension 1; fax 206–
766–5680; Internet https://
www.myboeingfleet.com. You may view
this referenced service information at
the FAA, Transport Airplane
Directorate, 1601 Lind Avenue SW.,
Renton, WA. For information on the
availability of this material at the FAA,
call 425–227–1221. It is also available
on the Internet at https://
www.regulations.gov by searching for
and locating Docket No. FAA–2012–
0187.
Examining the AD Docket
You may examine the AD docket on
the Internet at https://
www.regulations.gov by searching for
and locating Docket No. FAA–2012–
0187; or in person at the Docket
Management Facility between 9 a.m.
and 5 p.m., Monday through Friday,
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except Federal holidays. The AD docket
contains this proposed AD, the
regulatory evaluation, any comments
received, and other information. The
street address for the Docket Office
(phone: 800–647–5527) is in the
ADDRESSES section. Comments will be
available in the AD docket shortly after
receipt.
FOR FURTHER INFORMATION CONTACT: Jon
Regimbal, Aerospace Engineer,
Propulsion Branch, ANM–140S, FAA,
Seattle Aircraft Certification Office
(ACO), 1601 Lind Avenue SW., Renton,
WA 98057–3356; phone: 425–917–6506;
fax: 425–917–6590; email:
jon.regimbal@faa.gov.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite you to send any written
relevant data, views, or arguments about
this proposed AD. Send your comments
to an address listed under the
ADDRESSES section. Include ‘‘Docket No.
FAA–2012–0187; Directorate Identifier
2011–NM–094–AD’’ at the beginning of
your comments. We specifically invite
comments on the overall regulatory,
economic, environmental, and energy
aspects of this proposed AD. We will
consider all comments received by the
closing date and may amend this
proposed AD because of those
comments.
We will post all comments we
receive, without change, to https://
www.regulations.gov, including any
personal information you provide. We
will also post a report summarizing each
substantive verbal contact we receive
about this proposed AD.
Discussion
We issued an NPRM to amend 14 CFR
part 39 by adding an AD that would
apply to certain The Boeing Company
Model 757 airplanes. The NPRM
published in the Federal Register on
March 1, 2012 (77 FR 12506). The
NPRM proposed to require modifying
the fuel quantity indication system
(FQIS) wiring or fuel tank systems to
prevent development of an ignition
source inside the center fuel tank. We
subsequently issued an NPRM (77 FR
33129, June 5, 2012) to reopen and
extend the comment period for an
additional 2 months.
Related Service Information Under 1
CFR Part 51
We have reviewed Boeing Service
Bulletin 757–28–0136, dated June 5,
2014. This service information describes
procedures for the built-in test
equipment test/procedure (BITE check)
specified in paragraph (h)(1) of this
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supplemental NPRM. For information
on the procedures and compliance
times, refer to this service information.
This service information is reasonably
available; see ADDRESSES for ways to
access this service information.
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Comments
We gave the public the opportunity to
comment on the NPRM (77 FR 12506,
March 1, 2012). The following presents
the comments received on the NPRM
and the FAA’s response to each
comment.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012): Unjustified by
Risk
Boeing and Airbus requested that we
withdraw the NPRM (77 FR 12506,
March 1, 2012). Airbus requested that
we consider risk levels before pursuing
anticipated ADs for similar models.
Boeing’s request was based on a
determination that the risk posed by the
FQIS is not high enough to warrant AD
action. Boeing described the detailed
design features that it considers make
the failures contributing to the unsafe
condition unlikely. Boeing added that
its own numerical probability analysis
of the average risk level due to the
combination of failures required to
cause a fuel tank explosion is on the
order of one catastrophic event per
billion flight hours. Boeing pointed out
that this probability level would meet
the certification standard for systems
contained in section 25.1309(b) of the
Federal Aviation Regulations (14 CFR
25.1309(b)). Boeing also pointed out
that, because the Model 757 is out of
production and has a limited remaining
fleet life, the total risk of a catastrophic
event occurring in the remaining fleet
life is approximately 0.5 percent. Boeing
also noted that if a conductive condition
were to exist between the probes or
wiring and structure, it would be
identified by FQIS faults and therefore
would not be latent for multiple flights.
We disagree with the request to
withdraw the NPRM (77 FR 12506,
March 1, 2012). Average risk per flight
hour and total fleet risk were not the
safety criteria that drove the FAA to
propose the AD. In addition to
examining average risk and total fleet
risk, the FAA examines the individual
flight risk on the worst reasonably
anticipated flights. FAA Transport
Airplane Risk Assessment Methodology
(TARAM) Policy Statement PS–ANM–
25–05 (https://rgl.faa.gov/
Regulatory_and_Guidance_Library/
rgPolicy.nsf/0/4E5AE870716467
4A862579510061F96B?Open
Document&Highlight=ps-anm-25–05)
calls for the FAA to assess individual
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flight safety risk in consideration of preexisting hidden failure conditions and
accounts for dispatch with inoperative
equipment. The TARAM policy
classifies a flight dispatch condition as
‘‘reasonably anticipated’’ if, in absence
of corrective action, ten or more flights
are expected to occur.
Average risk is an arithmetic average
of the risk of a given event during all
operation of an aircraft fleet, regardless
of whether the risk actually varies
during the operation of the fleet. We use
average risk analysis to assess whether
a risk is acceptable when there is little
or no variation in risk from flight to
flight. Total fleet risk is the aggregate
sum of all risk throughout a fleet during
the remaining fleet life. Total fleet risk
analysis is meaningful in assessing total
societal risk, but it does not assess the
variation in risk between flights or the
risk on the worst anticipated flights.
Individual flight risk as used by the
FAA is an assessment of the specific
safety risk that exists or will exist on the
worst reasonably anticipated individual
flights due to a given issue.
Individual risk analysis is used by the
FAA to determine whether the public’s
expectation for a reasonable level of
safety on each transport airplane flight
is met. An acceptable average risk level
and acceptable total fleet risk do not
ensure that all reasonably anticipated
flights (flights with known inoperative
equipment, flights with undetected
failures, flights in less-than-ideal but
approved and expected weather or
operational conditions, etc.) will
provide the minimum level of safety
expected by the public. When the safety
risk is concentrated on flights with a
given pre-existing dispatch condition or
expected operational condition, it is
possible to have an unacceptable
individual flight safety risk on the worst
reasonably anticipated flights even
when the average risk and total fleet risk
are acceptable.
In the case of this SNPRM, the risk
due to the current Model 757 FQIS
design architecture is not spread equally
among all of the flights conducted on
the affected airplanes. Instead, the risk
is concentrated almost entirely on the
small subset of flights that occur with a
latent failure condition pre-existing in
the fuel tank. Flights with such a latent
failure condition and flammable
conditions in the center fuel tank have
been judged by the FAA to be
reasonably anticipated to occur based
on the numerical probability analysis
submitted by the manufacturer in
response to Special Federal Aviation
Regulation No. 88 (‘‘SFAR 88,’’
Amendment 21–78, and subsequent
Amendments 21–82 and 21–83) (https://
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rgl.faa.gov/Regulatory_and_Guidance_
Library%5CrgFAR.nsf/0/EEFB3F94451
DC06286256C93004F5E07?Open
Document) and the flammability
analysis submitted to support
certification of Boeing’s flammability
reduction means (FRM), which Boeing
refers to as a nitrogen generation system
(NGS). For those reasonably anticipated
flights, the probability of a catastrophic
event (or individual flight safety risk) is
the probability of an additional single
failure in the related aircraft wiring or
equipment sending a high energy signal
onto the already compromised in-tank
circuit(s). The individual flight safety
risk of a catastrophic event on these
flights is in excess of the FAA’s
threshold for an unsafe condition
determination contained in the
published TARAM Policy Statement
PS–ANM–25–05 (https://rgl.faa.gov/
Regulatory_and_Guidance_Library/
rgPolicy.nsf/0/4E5AE870716467
4A862579510061F96B?Open
Document&Highlight=ps-anm-25-05).
As discussed above, this risk of a
catastrophic event on those flights is
due to a single additional failure
condition. The risk on those flights due
to a single failure violates the FAA’s
general fail-safe design requirements
philosophy for transport airplanes. In
general, we issue ADs in cases where
reasonably anticipated flights with preexisting failures (either due to latent
failure conditions or allowable dispatch
configurations) are vulnerable to a
catastrophic event due to an additional
foreseeable single failure condition.
This is because the FAA considers
operation of flights vulnerable to a
potentially catastrophic single failure
condition to be an excessive safety risk
to the passengers on those flights. This
SNPRM is consistent with that
continued operational safety
philosophy.
In its comment, Boeing stated that the
existing design meets the numerical
probability requirements of section
25.1309(b) of the Federal Aviation
Regulations (14 CFR 25.1309(b)), which
requires safety analysis of systems.
Boeing concluded that the existing
system would need no further risk
reduction to meet the requirements of
that rule. We disagree with this
conclusion. First, the existence of a
general safety standard, even if met by
a design, does not in and of itself
preclude a determination that there is a
specific unsafe condition. The
recognition that compliance with an
existing regulation may not be sufficient
to ensure safety is specifically addressed
in type certification by section
21.21(b)(2) of the Federal Aviation
Regulations (14 CFR 21.21.(b)(2)) and
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has often led to changes in regulations
to address newly recognized unsafe
conditions. Second, because Boeing
mentioned only that rule, we infer that
Boeing may be suggesting that section
25.1309(b) of the Federal Aviation
Regulations (14 CFR 25.1309(b)) is the
most relevant safety analysis standard
applicable to the FQIS. As discussed
above, even if later changes to section
25.981 of the Federal Aviation
Regulations (14 CFR 25.981) are not
considered and only the original
certification basis for the Model 757 is
applied, there are safety standards more
specific to powerplant installations
including fuel tanks and FQIS than
section 25.1309(b) of the Federal
Aviation Regulations (14 CFR
25.1309(b)).
The original certification basis for
Model 757 airplanes included section
25.901(c) of the Federal Aviation
Regulations (14 CFR 25.901(c)) (https://
rgl.faa.gov/Regulatory_and_Guidance_
Library/rgFar.nsf/FARSBySectLookup/
25.901) at Amendment 25–40.
According to that subsection, ‘‘For each
powerplant and auxiliary power unit
installation, it must be shown that no
single failure or malfunction or probable
combination of failures will jeopardize
the safe operation of the airplane. . . .’’
(The FQIS is considered to be part of the
powerplant installation in accordance
with the definition in section 25.901(a)
of the Federal Aviation Regulations (14
CFR 25.901(a)).) Section 25.901(c) of the
Federal Aviation Regulations (14 CFR
25.901(c)) sets a more stringent
applicable standard than that of section
25.1309(b) of the Federal Aviation
Regulations (14 CFR 25.1309(b)) for
catastrophic failure conditions that are
due to latent failure conditions
combined with a subsequent single
failure condition (referred to as ‘‘latentplus-one’’ conditions).
The more stringent intent of section
25.901(c) of the Federal Aviation
Regulations (14 CFR 25.901(c)) (https://
rgl.faa.gov/Regulatory_and_Guidance_
Library/rgFar.nsf/FARSBySectLookup/
25.901) is discussed in further detail in
the notice of proposed rulemaking and
the preamble that were published for
Amendment 25–102. The FAA’s longstanding practice in applying the ‘‘no
single failure or malfunction’’ clause of
section 25.901(c) of the Federal Aviation
Regulations (14 CFR 25.901(c)) has been
to apply that standard to all reasonably
anticipated flights—not simply to an
average flight or an ideal flight. As such,
we examine all conditions: Flights with
reasonably anticipated pre-existing
failure conditions, flights with
inoperative equipment allowed for
dispatch, and flights in adverse
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environmental conditions or other
operational conditions for which the
airplane is approved. If single failure
conditions that jeopardize safe
operation of the airplane (catastrophic
or hazardous conditions) are identified
as part of this examination, the design
is considered to be non-compliant with
section 25.901(c) of the Federal Aviation
Regulations (14 CFR 25.901(c)).
Finally, the SFAR 88 AD-decision
policy (Policy Memo ANM–100–2003–
112–15) (https://rgl.faa.gov/Regulatory_
and_Guidance_Library/rgPolicy.nsf/0/
DC94C3A46396950386256D5E006
AED11?OpenDocument&Highlight
=anm-100-2003-112-15) classifies a
‘‘latent-plus-one’’ condition in a high
flammability fuel tank as an unsafe
condition requiring corrective action.
That policy actually provides some
relief from the latent-plus-one criteria
contained in the airworthiness
regulations.
We have not changed this SNPRM
regarding this issue.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012): Not Supported
by Risk Analysis
Airlines for America (A4A) proposed
that we re-evaluate the NPRM (77 FR
12506, March 1, 2012) because it is ‘‘not
founded on a data-based risk analysis.’’
A4A stated that the FAA determined
that an unsafe condition exists based
only on non-compliance with one SFAR
88 criterion. A4A noted that the design
approval holder, Boeing, has performed
a numerical probability analysis and has
calculated that the probability of a fuel
tank explosion due to the FQIS issue is
approximately one event per billion
flight hours, with cargo airplanes being
slightly better due to a lower average
tank flammability. A4A also stated that
existing ignition-prevention ADs have
reduced the overall risk of an ignition
event to a level that questions the need
for FQIS modification. We infer that the
commenter is requesting that we
withdraw the NPRM.
We disagree to withdraw the NPRM
(77 FR 12506, March 1, 2012). We
performed a qualitative risk assessment
in accordance with our published SFAR
88 unsafe condition determination
policy based on Boeing’s submitted
SFAR 88 design review, and determined
that the FQIS design on the Model 757
series airplanes presents an unsafe
condition and that AD action was
warranted under that policy. We also
performed a data-based numerical risk
analysis using data provided by the
manufacturer, and assessed the risk
under the transport airplane unsafe
condition criteria in the TARAM policy
currently used by the FAA. Our risk
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analysis determined that the risk of an
explosion event due to an FQIS latentplus-one failure condition is not evenly
shared by all flights of airplanes of the
affected design. Instead, the risk of an
FQIS-related fuel tank ignition event is
largely concentrated on the subset of
flights that occur with a pre-existing
latent failure condition and that operate
with flammable conditions in the center
fuel tank. Based on Boeing’s data, such
flights are reasonably anticipated to
occur.
For those flights, the risk exceeds the
allowable threshold for individual flight
safety risk in the TARAM policy. In
addition, that risk on those flights is due
to a single additional failure, which is
inconsistent with the fail-safe design
philosophy; that philosophy is
fundamental to the excellent safety
record of transport airplanes. (See FAA
Advisory Circular (AC) 25.1309–1A,
‘‘System Design and Analysis,’’ dated
June 21, 1998 (https://www.faa.gov/
documentLibrary/media/Advisory_
Circular/AC%2025.1309-1.pdf), for a
discussion of the fail-safe design
philosophy.) We would normally
classify either of those conditions as an
unsafe condition. Based on this risk
analysis, we have determined that the
individual flight safety risk due to this
issue on the worst anticipated flights
does not meet the minimum level of
safety required by the FAA and
expected by the public. We have not
changed this SNPRM regarding this
issue.
Request To Withdraw or Delay NPRM
(77 FR 12506, March 1, 2012): Need
Detailed Risk Assessment
FedEx requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
provide a numerical risk assessment
justifying the proposed action. UPS
made a similar comment. UPS stated
that, if the FAA has gathered new data
since the issuance of the ‘‘Reduction of
Fuel Tank Flammability in Transport
Category Airplanes’’ rule (73 FR 42444,
July 21, 2008) (https://www.gpo.gov/
fdsys/pkg/FR-2008-07-21/pdf/E816084.pdf), referred to as the Fuel Tank
Flammability Reduction (FTFR) rule,
the FTFR working group should be
reconvened in order to collaborate and
discuss the proposed safety risk, assess
the risk statistically, evaluate solutions
and options, and establish accurate cost
and economic impact for the options.
FedEx provided an analysis showing
that the total risk of a tank explosion
due to this issue on the fleet of Model
757 cargo airplanes is relatively low. We
infer that the commenters are requesting
that we withdraw or delay the NPRM.
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We disagree with the request to
withdraw the NPRM (77 FR 12506,
March 1, 2012), pending review of the
FAA’s numerical risk assessment by the
‘‘FTFR working group.’’ The Aviation
Rulemaking Advisory Committee
(ARAC) Fuel Tank Harmonization
Working Group (FTHWG) was tasked to
recommend new rulemaking to
eliminate or significantly reduce the risk
of exposure to flammable fuel-air
mixtures in fuel tanks. The ARAC
FTHWG issued its final report in 1998.
The subsequent ARAC Fuel Tank
Inerting Harmonization Working Group
(FTIHWG) was tasked to provide data
needed for the FAA to evaluate the
feasibility of implementing regulations
that would require eliminating or
significantly reducing the development
of flammable vapors in fuel tanks on
transport-category airplanes. This effort
was an extension of the previous work
performed by the FTHWG. The ARAC
FTIHWG issued its final report in 2002.
The FAA’s work in developing the
SFAR 88 corrective action decision
policy and in determining specific
unsafe conditions was outside the scope
and charter of these working groups that
contributed to the FTFR rule (73 FR
42444, July 21, 2008). We determined
that an unsafe condition exists in
accordance with the SFAR 88 corrective
action decision policy and TARAM
policy. We have provided a summary of
our risk assessment as discussed in the
responses to ‘‘Request to Withdraw
NPRM (77 FR 12506, March 1, 2012):
Unjustified by Risk’’ and ‘‘Request to
Withdraw NPRM (77 FR 12506, March
1, 2012): Not Supported by Risk
Analysis’’ in this SNPRM. As explained
previously (see ‘‘Request to Withdraw
NPRM (77 FR 12506, March 1, 2012):
Unjustified by Risk’’ in this SNPRM),
the FAA determined the unsafe
condition based on the unacceptable
risk on anticipated flights with a latent
FQIS failure and flammable fuel tank
conditions, not the total fleet risk. We
have not changed this SNPRM regarding
this issue.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012): No Unsafe
Condition
UPS stated that an SFAR 88 working
group analyzed potential fuel tank
ignition sources and that maintenance
programs were revised using MSG3
methodology to meet the revised criteria
in ‘‘14 CFR 25.981(3).’’ (We assume UPS
intended to refer to section 25.981(a)(3)
of the Federal Aviation Regulations (14
CFR 25.981(a)(3))) (https://www.faa.gov/
regulations_policies/advisory_circulars/
index.cfm/go/document.information/
documentID/73716).) UPS stated that
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the unsafe condition identified in the
NPRM is inconsistent with the working
group analysis and lacks new data or
evidence indicating that ‘‘excessive
flammability or other known unsafe
condition exists, or is likely to
develop.’’ Finally, UPS made the
following observation about the NPRM:
therefore would not have a significant
effect on either the number of flights
that occur with a latent failure condition
or the FQIS-related fuel tank explosion
risk level on those flights estimated in
the FAA’s risk assessment. We have not
changed this SNPRM regarding this
issue.
The NPRM fails to consider the beneficial
effects of the timing and effects of the
maintenance action in response to a single
in-tank or out-of-tank failure mode, or the
beneficial effects of previous airworthiness
directives and other SFAR 88 related actions
taken to mitigate the proposed risk and
reduce the probability.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012): No Unsafe
Condition
Airbus acknowledged that the latentplus-one scenarios that prompted the
unsafe condition determination are a
technical possibility, but stated that the
failure combinations that can create an
ignition source are extremely
improbable. Airbus also stated that ADrequired airworthiness limitations
related to FQIS have significantly
reduced the likelihood of an FQISrelated fuel tank ignition event. We infer
that Airbus is requesting that we
withdraw the NPRM (77 FR 12506,
March 1, 2012) based on Airbus’s
contention that no unsafe condition
exists.
We agree to clarify the likelihood that
the unsafe condition could occur. The
FAA’s unsafe condition determination
was not based on an assessment of
average risk. We agree that the average
risk of a fuel tank explosion on the
Model 757 is likely to be lower than the
numerical guidance for ‘‘extremely
improbable’’ of 1.0x10E–9 per flight
hour. We also agree that the average risk
was likely reduced by AD-required
airworthiness limitations that specify
extra checks after in-tank work, and
adequate separation of newly installed
out-of-tank wiring from FQIS wiring.
As discussed in ‘‘Request to
Withdraw NPRM (77 FR 12506, March
1, 2012): Unjustified by Risk’’ in this
SNPRM, however, the FAA’s unsafe
condition determination was driven by
the identification of an unacceptable
level of individual risk that exists on
flights that are anticipated to occur with
a pre-existing latent in-tank failure
condition and with a flammable center
fuel tank. In the remaining life of the
affected airplanes, a significant number
of such flights are reasonably
anticipated to occur—even with the
improvements expected under the
AWLs required by AD 2012–12–15,
Amendment 39–17095 (77 FR 42964,
July 23, 2012). For those flights, a fuel
tank explosion can be caused by an
additional single wiring failure. In
addition, the manufacturer’s estimated
probability of such a failure (the
additional single wiring failure)
significantly exceeds the FAA’s unsafe
condition numerical threshold for
individual flight risk. The probability of
We infer that the commenter is
requesting that we withdraw the NPRM
(77 FR 12506, March 1, 2012). We
disagree with the request to withdraw
the NPRM. The FAA has performed a
risk assessment and has determined that
an unsafe condition does exist, both
from a design architectural standpoint
and a numerical risk standpoint. The
basis for that determination is discussed
in detail in the responses to ‘‘Request to
Withdraw NPRM (77 FR 12506, March
1, 2012): Unjustified by Risk’’ and
‘‘Request to Withdraw NPRM (77 FR
12506, March 1, 2012): Not Supported
by Risk Analysis’’ in this SNPRM.
The requirements of section
25.981(a)(3) of the Federal Aviation
Regulations (14 CFR 25.981(a)(3))
cannot be met with an approved
maintenance program only. While an
appropriate maintenance program is
required, section 25.981(a)(3) of the
Federal Aviation Regulations (14 CFR
25.981(a)(3)) has the effect of setting
minimum requirements for the design
architecture and the reliability of system
elements. The Model 757 FQIS as
originally designed does not meet all of
those requirements. Previous AD
actions, other than the required
maintenance program revisions
included in AD 2012–12–15,
Amendment 39–17095 (77 FR 42964,
July 23, 2012) (which superseded AD
2008–10–11, Amendment 39–15517 (73
FR 25974, May 8, 2008)), have no effect
on the level of individual flight risk that
has been determined to be an unsafe
condition. Some of the airworthiness
limitations (AWLs) introduced by AD
2012–12–15 will reduce the rate of
introduction of additional risks due to
future maintenance errors or
modifications compromising required
design features, but are not expected to
prevent all errors. Those AWLs do not
address problems that may already exist
or develop on in-service airplanes
separate from maintenance activity, and
they do not address the basic noncompliant aspects of the original FQIS
design architecture. Those AWLs
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a fuel tank explosion on those flights is
not reduced by the existence of the
above-mentioned AWLs. The AWL that
requires extra checks after in-tank work
has been done has the potential to
reduce the number of flights with a preexisting in-tank failure condition. The
AWL that requires newly installed
wiring to meet separation standards
should prevent a significant increase in
the risk on those flights that would have
resulted from the installation of
additional, inadequately separated
wiring.
We have not changed this SNPRM
regarding this issue.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012) Based on Similar
Rulemaking for Cargo Airplanes
ASTAR Air Cargo (ASTAR) requested
that we withdraw the NPRM (77 FR
12506, March 1, 2012). In support of its
request, ASTAR cited the TWA Flight
800 accident investigation and its
finding that the most probable cause of
the accident was a fuel tank explosion
due to a latent-plus-one failure of the
FQIS. ASTAR stated that the FAA had
proposed the FTFR rule (73 FR 42444,
July 21, 2008) to mitigate the risk of fuel
tank explosions, and that cargo
airplanes had been exempted from that
requirement based on a cost-benefit
analysis. ASTAR argued that, because
the basis for exclusion of all cargo
aircraft from the FTFR rule has not
changed, all cargo aircraft should be
exempt from any corrective action for
the FQIS latent-plus-one issues, and the
NPRM (77 FR 12506, March 1, 2012)
should be withdrawn.
We disagree with the request. We
have determined that an unsafe
condition requiring corrective action
exists in the Model 757 FQIS. The FTFR
rule (73 FR 42444, July 21, 2008) was
proposed not because of FQIS issues
specifically, but because of the history
of fuel tank explosions in the transport
airplane fleet due to various causes, and
an acknowledgement that industry and
the FAA may not be able to anticipate
and prevent all of the fuel tank ignition
sources that may arise due to design and
maintenance issues in the life of a fleet
of airplanes.
The intent of the FTFR rule (73 FR
42444, July 21, 2008) was to reduce the
overall exposure to flammable fuel tank
conditions in the fleet by approximately
one order of magnitude with the
expectation that this would have a
significant impact on the rate of fuel
tank explosions in the future due to
unanticipated causes. In promulgating
this improvement in the safety
standards, the FAA acknowledged that
installation of FRM or ignition
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mitigation means on a given airplane in
accordance with the FTFR rule would
be sufficient to address the FQIS latentplus-one unsafe condition. The FTFR
rule was not intended to prevent the
FAA from addressing that unsafe
condition on airplanes that would not
be affected by the FTFR rule. This was
clearly stated in the preamble to the
FTFR rule. We have not changed this
SNPRM regarding this issue.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012): Underestimated
Economic Impact
Several commenters requested that we
withdraw the NPRM (77 FR 12506,
March 1, 2012) because the FAA’s cost
estimate was too low. A4A estimated
that the costs associated with the NPRM
would be up to 3 times the $100,000 to
$200,000 estimated by the FAA, and
would be comparable with the cost of
Boeing’s NGS installation. Goodrich
pointed out that any redesigned FQIS
would likely be subject to the current
requirements of section 25.981 of the
Federal Aviation Regulations (14 CFR
25.981), resulting in higher costs than
estimated by the FAA. A4A speculated
that these higher costs were the reason
the NGS was acknowledged as a method
of compliance in the NPRM. A4A and
UPS stated that the FAA appears to be
using the NPRM as a method to require
the installation of Boeing’s NGS (or
equivalent actions) on airplanes that
were not included in the applicability of
the FTFR rule (73 FR 42444, July 21,
2008) based on a cost-benefit analysis.
Although we disagree to withdraw the
NPRM, we agree with some of the
commenters’ assertions. We agree that
our original cost estimate was low. We
agree to adjust the cost estimate, based
on the information provided by the
commenters, as discussed below under
‘‘Request to Revise Cost Estimate Based
on New Data.’’ Our original estimate
was based on information provided
previously by manufacturers of original
equipment FQIS, retrofit FQIS, and both
original equipment and aftermarket
transient suppression and isolation
devices. Our current estimate has been
increased to reflect the written
comments from and further discussions
with Boeing and Goodrich. There is no
change to our determination that an
unsafe condition exists. We are
therefore proceeding with this AD
action based on the identified corrective
actions that will address the unsafe
condition.
We disagree with the characterization
that we are using the AD process to
require an FRM to be installed on
airplanes that were excluded from the
FTFR rule (73 FR 42444, July 21, 2008)
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because inclusion could not be justified
in a cost-benefit analysis. The FTFR rule
was intended to enhance the
airworthiness standards in a manner
that would increase the level of safety
for affected airplanes over that ensured
by the existing regulations. That
enhancement was expected to result
from an increased level of protection
from ignition sources that had not been
identified by manufacturers in their
safety analyses. That enhancement of
the airworthiness standards was
required to be justified by a cost-benefit
analysis. Cargo airplanes were excluded
because the FTFR rule safety
enhancement could not be justified for
those airplanes from a cost-benefit
standpoint.
This SNPRM would not require a
safety enhancement over the level of
safety required by previous standards.
Instead, this SNPRM addresses an
unsafe condition that was identified
from the manufacturer’s SFAR 88 safety
analysis using the FAA’s published
corrective action decision criteria for
SFAR 88 identified design issues (see
section 25.981(a)(3) of the Federal
Aviation Regulations (14 CFR
25.981(a)(3) (https://www.faa.gov/
regulations_policies/advisory_circulars/
index.cfm/go/document.information/
documentID/73716). We deferred taking
action on this unsafe condition until
after the FTFR rulemaking activity
because the installation of an FRM
would sufficiently address the FQIS
latent-plus-one unsafe condition. Now
that the FTFR rulemaking process is
complete, we are resuming our activity
to address these unsafe conditions via
AD actions. The Boeing NGS has been
acknowledged as a method of
compliance in this SNPRM because the
Boeing NGS is an available design that
the FAA knows would address the
unsafe condition. No additional change
was made to this SNPRM as a result of
this comment.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012) Due to Its
Hidden Effects
A4A requested that we withdraw the
NPRM (77 FR 12506, March 1, 2012)
because of certain hidden effects that
may not have been anticipated by the
FAA. A4A pointed out that some
operators are already anticipating
difficulty in meeting the deadlines for
compliance with the FTFR rule (73 FR
42444, July 21, 2008). Based on A4A’s
assumption that airlines would comply
with the NPRM by incorporating
Boeing’s current NGS design, A4A
expressed concern that using Boeing’s
NGS for these additional airplanes
would potentially exceed the rate at
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which industry can modify the fleet
affected by the planned ADs and the
FTFR rule. A4A also noted that the
compliance time for the NPRM would
overlap the compliance period for the
FTFR rule.
While we disagree with the request to
withdraw the NPRM, we agree with
some of the assertions made by the
commenter. We agree with the concern
that this AD action has the potential to
further burden the operators and
modifiers that are working to meet the
FRM operating rule deadlines, because
some additional airplanes are likely to
be modified by installing FRM such as
Boeing’s NGS. But since we issued the
NPRM (77 FR 12506, March 1, 2012),
two factors have changed that reduce
A4A’s concern. First, we have identified
a less costly option for cargo airplanes,
which most cargo operators are
expected to prefer over installation of
FRM. This is expected to result in
significantly fewer airplanes competing
for FRM modification resources.
Second, this AD action has been
delayed due to numerous factors,
including the number of comments, the
development of a different corrective
action option, and the resultant need to
extend the comment period to allow the
public the chance to comment on these
proposed changes.
Also, as discussed below under
‘‘Request to Extend Compliance Time
Pending Issuance of Service
Information,’’ we have extended the
proposed compliance time by 12
months. These delays and changes will
result in the AD compliance deadline
being at least 3 years beyond the final
compliance deadline of the FTFR rule
(73 FR 42444, July 21, 2008). Similar
planned ADs for other models have
been similarly delayed. We have
determined that the industry
modification capacity will be sufficient
to support the modification of the
expected additional airplanes receiving
FRM within the new proposed
compliance time. We have not changed
this SNPRM further regarding this issue.
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Request To Withdraw NPRM (77 FR
12506, March 1, 2012): Potential
Significant Rule
A4A stated that the combined costs of
the NPRM (77 FR 12506, March 1, 2012)
and other anticipated ADs for U.S.
airplane models with an FQIS latentplus-one issue would exceed $177
million and would require a cost-benefit
analysis. We infer that the commenter is
requesting we withdraw the NPRM (77
FR 12506, March 1, 2012) on the basis
that the planned ADs for various
models, if combined, would qualify as
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a significant rule that would require a
cost-benefit analysis.
We disagree with the request. First, in
assessing whether an AD is a significant
rule in accordance with FAA policy, we
do not combine the cost of multiple
planned ADs for different airplanes,
even when the design issues and unsafe
conditions addressed are similar.
Second, the changes discussed
previously in this SNPRM will
significantly reduce the cost impact. We
have made no further changes to this
SNPRM regarding this issue.
Request To Withdraw NPRM (77 FR
12506, March 1, 2012): Inadequate
Notice to Public
A4A recommended that we provide
information on any other designs that
have been reviewed under SFAR 88,
and provide industry with information
regarding their planned disposition.
A4A asserted that, during the FTFR
rulemaking activity, we did not provide
notice to the industry that we still
intended to address the FQIS issues
identified via SFAR 88. We infer that
A4A is requesting that we withdraw the
NPRM (77 FR 12506, March 1, 2012)
based on inadequate notice to the public
and the chance to comment on the
proposal. The commenter stated that the
preamble of the FTFR rule (73 FR
42444, July 21, 2008) was unclear
regarding whether AD actions would be
taken to address the FQIS issues on
airplanes that were not required to
incorporate FRM.
We disagree with the request to
withdraw the NPRM (77 FR 12506,
March 1, 2012). We determined that an
unsafe condition exists. FTFR
rulemaking was done because the FAA
recognized the benefit for the specific
design changes involving incorporation
of FRM required by the FTFR rule (73
FR 42444, July 21, 2008) to enhance fuel
tank safety. Because the FTFR final rule
requires action on only a subset of the
airplanes that have the FQIS unsafe
condition, we are taking action to
address the remaining airplanes that
will continue to have the unsafe
condition if no further corrective action
is taken.
The commenter has taken the
statement from the FTFR preamble out
of context. In fact, the paragraph from
which the commenter quoted
specifically states that the FAA
expected to take AD action to address
FQIS issues identified through SFAR 88
analyses. The paragraph simply states
that the proposed FRM has the potential
to reduce the industry cost associated
with those expected ADs because the
installation of an FRM likely would
eliminate the need for action to further
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9405
address the FQIS issue with AD actions.
The purpose of that statement was to
note that there would be some cost
savings to industry resulting from the
elimination of other actions required to
address an unsafe condition for the
airplanes affected by the proposed rules,
and to point out that the FAA did not
take credit for those potential cost
reductions in assessing the cost of the
FTFR rule (73 FR 42444, July 21, 2008)
because the costs were not well
understood at the time. That statement
was not a commitment by the FAA to
reverse its intentions to address an
identified unsafe condition on the
airplanes that are not required to
incorporate FRM. We have not changed
this SNPRM regarding this issue.
Request for Cost-Benefit Analysis
Boeing, FedEx, Airbus, ASTAR Air
Cargo, and A4A requested that we
perform a cost-benefit analysis for the
NPRM (77 FR 12506, March 1, 2012)
and publish the results. Airbus stated
that its own cost estimates exceed those
used by the FAA for the FTFR rule (73
FR 42444, July 21, 2008) cost-benefit
analysis that ended up excluding cargo
airplanes. A4A and ASTAR Air Cargo
requested that the NPRM be withdrawn
until a cost-benefit analysis is
performed. The commenters suggested
that a cost-benefit analysis would show
that the NPRM cannot be justified
because the costs of the proposed
actions would exceed the monetary
value of the AD’s safety benefits. The
commenters cited the cost-benefit
analysis that was performed to justify
the FTFR rule, and pointed out that a
requirement for FRM could not be
justified for the airplanes that would be
affected by the proposed AD.
We infer that, pending a full costbenefit analysis, these commenters are
requesting that we either withdraw the
NPRM or delay this action further until
a cost-benefit analysis demonstrates that
an AD is justified in this case. We
disagree. The FAA’s process and legal
obligations for introducing new
airworthiness standards are different
from those for initiating an AD to
address an unsafe condition in an
existing product. In addition, the
commenters’ assertions were based on
the assumption that the only design
solution that would be made available
to address the solution would be an
FRM, or another solution of similarly
high cost.
When we propose a new
airworthiness standard, as in the case of
the FTFR rule (73 FR 42444, July 21,
2008), we are required to perform a costversus-benefit comparison to justify the
application of the new standard. The
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decision in that rulemaking action—to
not require FRM installation on cargo
airplanes—was based in significant part
on cost estimates that industry provided
to show that AD-required FQIS design
changes would be far less costly than
installing FRM on cargo airplanes. We
specifically considered the option to not
require retrofit of cargo airplanes with
FRM because of the expectation that
alternative design solutions to address
the specific, known unsafe condition of
FQIS latent-plus-one vulnerability
would still be required through AD
actions. For this AD action, however,
industry submitted written comments
and made verbal statements that the cost
of an FQIS design solution would be
comparable to, and possibly greater
than, the cost of its FRM modification.
In general, a full cost-benefit analysis
is rarely required for an AD. As a matter
of regulation, in order to be airworthy,
an aircraft must conform to its type
design and be in a condition for safe
operation. The type design is approved
only after the FAA makes a
determination that the design complies
with all applicable airworthiness
requirements. In adopting and
maintaining those requirements, the
FAA has already made the
determination that those requirements
establish a level of safety that is cost
beneficial. A finding of an unsafe
condition that warrants AD action
means that this cost-beneficial level of
safety is no longer being achieved, and
the required AD actions are necessary to
restore that level of safety. Because this
level of safety has already been
determined to be cost beneficial and
does not add an additional regulatory
requirement, a full cost-benefit analysis
for each AD would be redundant and
unnecessary.
We have not changed this SNPRM
regarding this issue.
Request To Revise Applicability
Statement To Clarify the Intent of the
Rule for Non-U.S.-Registered Airplanes
The European Aviation Safety Agency
(EASA), the Technical Agent for the
Member States of the European
Community, requested that we revise
the proposed applicability. Specifically,
EASA requested that we add Model 757
airplanes that did not have FRM
installed in production. EASA further
requested that we exclude airplanes
equipped with FRM that meet the FAA’s
FTFR rule (73 FR 42444, July 21, 2008).
EASA stated that it has not issued an
operating regulation corresponding to
the FAA’s requirements for retrofitting
FRM in the FTFR rule. EASA noted that,
at least for European operators, the
unsafe condition would not be required
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to be addressed for airplanes that would
have been subject to the FTFR rule in
the U.S., and suggested that EASA
might have to issue an AD (instead of
adopting the FAA AD), with similar
technical content, but extending the
applicability to the entire Model 757
fleet in Europe.
We agree to revise the applicability.
EASA is correct that the unsafe
condition potentially affects all Model
757 airplanes, whereas the applicability
statement in the NPRM (77 FR 12506,
March 1, 2012) could be interpreted as
not covering airplanes in passenger
service that are not operated under parts
121, 125, or 129 of the Federal Aviation
Regulations (14 CFR part 121, 125, or
129). The EASA comment makes it
apparent that the proposed applicability
statement may be unclear to some
operators and regulatory authorities.
While the applicability statement in the
NPRM is technically correct (e.g., an
EASA operator is not operating under
those FAA operating rules and therefore
would have been subject to the AD), we
now agree that there is a potential for
confusion that can be eliminated by
more directly stating the requirement
and applicability in a manner similar to
that proposed by EASA in their
comment. We have changed the
applicability in this SNPRM to all
Model 757 airplanes except for
airplanes equipped with an FRM
approved by the FAA as compliant with
the FTFR requirements of section
26.33(c)(1) of the Federal Aviation
Regulations (14 CFR 26.33(c)(1)), as
discussed below. As with any required
equipment, the FRM must be
operational with the exception of any
relief granted under master minimum
equipment list (MMEL) provisions.
With the clarification in paragraph (c),
‘‘Applicability,’’ of this SNPRM, we
have determined that paragraph (h),
‘‘Optional Installation of Flammability
Reduction Means,’’ of the NPRM would
be superfluous and is no longer
necessary. Paragraph (c) of this
supplemental NPRM, as revised, would
not apply to airplanes equipped with
FRM.
Requests To Withdraw NPRM (77 FR
12506, March 1, 2012) Based on
Applicability
Boeing and ASTAR Air Cargo
requested that we withraw the NPRM
(77 FR 12506, March 1, 2012) because
cargo airplanes on average have a lower
flammability exposure due to a larger
portion of night operations (with
resultant cooler outside air
temperatures) and a lower rate of
utilization of the cabin air conditioning
system on the ground. Boeing stated that
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operation of the air conditioning system
on the ground significantly contributes
to the heating of the center fuel tank.
Boeing’s analysis estimated a fleet
average flammability for the center fuel
tanks of the cargo airplane fleet of 50
percent of the level for the passenger
fleet. Boeing also noted that cargo
airplanes generally accumulate flight
hours at a lower rate than passenger
airplanes.
We disagree with the request to
withdraw the NPRM (77 FR 12506,
March 1, 2012).
We acknowledge that the increased
night operation and reduced use of the
air conditioning system on the ground
reduce the average flammability
exposure for the fleet of cargo airplanes
relative to the fleet of passenger
airplanes. That reduction in fleet
average flammability, however, is not
sufficient to allow the center fuel tanks
on those airplanes to be classified as
low flammability fuel tanks. The FAA’s
determination that an unsafe condition
exists for the cargo airplanes as well as
passenger airplanes was driven by the
FAA’s individual risk safety decision
criteria rather than an average risk or
fleet risk criterion. There is no
difference in the individual flight risk
on the worst anticipated flights between
passenger airplanes and cargo airplanes
due to this issue. The worst anticipated
flights in either case involve a preexisting latent in-tank failure and
operation with flammable conditions in
the center fuel tank. Flights with that
combination of conditions are
anticipated to occur in both the
passenger fleets and cargo fleets
(although at a somewhat lower relative
rate on cargo airplanes, for the reasons
cited by the commenters).
For those flights, a fuel tank explosion
could occur due to a single failure in the
airplane wiring or the FQIS processor
that conducts a high level of electrical
energy onto circuits that enter the fuel
tank. As discussed previously in the
response to ‘‘Request to Withdraw
NPRM (77 FR 12506, March 1, 2012):
Unjustified by Risk,’’ this is not
consistent with the FAA’s fail-safe
design philosophy for transport
airplanes. In addition, the numerical
probability of the single failure as
estimated by the manufacturer and the
FAA significantly exceeds the unsafe
condition threshold for individual flight
risk in the FAA’s TARAM) Policy
Statement PS–ANM–25–05 (https://
rgl.faa.gov/Regulatory_and_Guidance_
Library/rgPolicy.nsf/0/4E5AE87071646
74A862579510061F96B?Open
Document&Highlight=ps-anm-25–05).
We have therefore determined that an
unsafe condition does exist on cargo
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airplanes even in consideration of the
lower fleet exposure factors cited by the
commenters.
While we have determined that this
unsafe condition requires corrective
action, we have identified additional
corrective action options that we expect
will be significantly less costly to
incorporate than the originally proposed
requirement. We have determined that
this additional corrective action option
is not suitable for passenger airplanes
because it does not provide a sufficient
level of risk reduction for passenger
operations. The FAA normally does not
differentiate between the safety
requirements or corrective action
requirements for cargo airplanes and
passenger airplanes. However, after
reviewing all of the comments on the
estimated high cost of the corrective
action and the uncertainty in those
estimates, we examined other options
for less costly risk reduction on cargo
airplanes. We identified an option that
provides significant risk reduction at a
per-airplane cost that is estimated to be
less than one-quarter of the cost of the
original proposal (77 FR 12506, March
1, 2012). The amount of risk reduction
from this option is not at this time
considered to be adequate to address the
unsafe condition for passenger
airplanes.
In this case, the FAA is proposing to
accept a higher level of individual flight
risk exposure for cargo flights that are
not fail-safe due to the absence of
passengers and the resulting significant
reduction in occupant exposure on a
cargo airplane versus a passenger
airplane, and due to relatively low
estimated individual flight risk that
would exist on a cargo airplane after the
corrective actions are taken. The FAA
has allowed a higher risk level to exist
on cargo airplanes due to other issues,
and applies a slightly less stringent
numerical fleet risk threshold standard
for unsafe conditions in the published
TARAM policy. Because this is an
unusual determination, we have
reopened the comment period to give
affected operators, pilots, and the public
the opportunity to comment on this
proposal.
We expect that the optional wire
separation design change to support
compliance with the proposed AD for
cargo airplanes will involve the
manufacturer or any other modifier
petitioning for a partial exemption from
the ‘‘latent-plus-one’’ requirements of
sections 25.901(c) and 25.981(a)(3) of
the Federal Aviation Regulations (14
CFR 25.901(c) and 14 CFR 25.981(a)(3)).
We have informed the manufacturer that
we are open to granting such an
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exemption, and they indicated their
willingness to make such a petition.
We have added new paragraph (h) in
this SNPRM to allow repetitive FQIS
built-in test equipment (BITE) checks
and modification of the airplane by
separating FQIS wiring from other
aircraft wiring that is not intrinsically
safe (in a manner acceptable to the FAA)
as an additional option for airplanes
used exclusively for cargo operations.
We have redesignated subsequent
paragraphs of this SNPRM accordingly.
Request To Change Applicability To
Address Unsafe Condition on Airplanes
With FRM
National Air Traffic Controllers
Association (NATCA) requested that we
revise the NPRM (77 FR 12506, March
1, 2012) to include airplanes on which
FRMs were incorporated either
voluntarily or to comply with the FTFR
rule (73 FR 42444, July 21, 2008).
NATCA noted that the introduction of
FRM on such airplanes only reduces the
fraction of time the airplane is operated
with flammable conditions in its fuel
tanks, but does not eliminate flammable
operation. NATCA further noted that
FAA operating rules allow limited
operation of the airplane with the FRM
inoperative. NATCA added that the
likelihood of a fuel tank explosion
during operation with flammable tanks
is similar regardless of whether an FRM
is installed.
We disagree with the request. We
have developed and published policy
for determination of unsafe conditions
and the need for corrective actions
during the evaluation of SFAR 88 fuel
tank safety review findings. The
decision to allow FRM as an acceptable
mitigating action for the identified
unsafe condition is consistent with that
policy. We acknowledge NATCA’s point
that, if no actions are taken on an
airplane to correct the FQIS latent-plusone issue other than installation of an
FRM, flights on that airplane where
FRM is inoperative or ineffective would
have the same risk of a fuel tank
explosion due to the FQIS latent-plusone issue as flights on an airplane with
no FRM installed. However, the
published unsafe condition criteria
(section 25.981(a)(3) of the Federal
Aviation Regulations (14 CFR
25.981(a)(3)) (https://www.faa.gov/
regulations_policies/advisory_circulars/
index.cfm/go/document.information/
documentID/73716) differentiate
between low- and high-flammability
fuel tanks, with a higher level of
conservatism applied to highflammability tanks.
The criteria recognize that lowflammability tanks are still flammable
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9407
for a portion of their operating time, and
the criteria include ignition prevention
thresholds commensurate with that
level of flammability. The regulatory
performance standard for FRMs is
equivalent to the flammability of a
conventional aluminum wing tank,
which is the benchmark for the
definition of a low-flammability tank.
We have therefore determined that it is
appropriate to treat ignition sources in
center fuel tanks with compliant FRMs
the same way they would be treated for
a tank that has inherent low
flammability. Because the FQIS latentplus-one vulnerability for Model 757
airplanes was classified as a theoretical
vulnerability and not as a condition
known to have occurred, the SFAR 88
corrective action policy does not require
corrective action for that condition in
low-flammability fuel tanks. The
installation of an FRM causes the center
fuel tank to meet the criteria for
classification as a low-flammablity fuel
tank, and therefore FRM installation
was considered to be acceptable
mitigating action. We have not changed
this SNPRM regarding this issue.
Request To Remove Requirement for
Goodrich FQIS
Goodrich stated that its FQIS fuel
height and dielectric sensor interface
circuitry presently meets the energy,
voltage, and current limits specified in
FAA AC 25.981–1C, ‘‘Fuel Tank Ignition
Source Prevention Guidelines,’’ dated
September 19, 2008 (https://
www.faa.gov/regulations_policies/
advisory_circulars/index.cfm/go/
document.information/documentID/
73716). Goodrich stated that the system
design would require multiple serial
failures to enable a fault to propagate to
the tank, resulting in the combination of
those failures being extremely
improbable on average. Goodrich added
that the system built-in test detects open
circuits and short circuits in the sensors
and aircraft wiring, including shorts to
structure. Goodrich stated that there
have been no failures in service in
which the Goodrich FQIS exposed the
fuel tank to an unsafe condition.
Goodrich asked whether the actual
system operation and service life have
been considered in the evaluation of the
probability of an unsafe condition and
the mitigation provided by the present
Goodrich FQIS.
We infer that the commenter is
requesting that we revise the NPRM (77
FR 12506, March 1, 2012) to eliminate
any requirement for corrective action for
airplanes equipped with a Goodrich
FQIS. We partially agree. The Goodrich
system is recognized as having
significant improvements relative to the
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original 757 system developed by
another manufacturer. We recognize
that the Goodrich FQIS has the ability
to identify a significant portion of the
potential latent in-tank failure
conditions that can occur inside the fuel
tanks. Those conditions, however, are
detected and corrected only when the
built-in test capability is activated
during maintenance. Currently,
activating the built-in test features is
required only when troubleshooting an
FQIS problem that has become apparent
to flight or maintenance crew. This still
potentially leaves significant latency
periods for those failures.
We have agreed that the Goodrich
processor has sufficient circuit isolation
such that the processor itself is not
expected to create hot short conditions
in tank circuits, and is not expected to
pass energy from non-tank-side lowvoltage hot shorts onto tank-side
circuits. There remains, however, a
significant potential for a single failure
causing a hot short onto tank-side
circuits, or a single failure causing a
high-voltage hot short onto non-tankside circuits to cause non-intrinsically
safe energy, voltage, or current levels to
be conducted into the fuel tanks. The
latent-plus-one concern therefore still
exists even with the additional
detection capabilities that exist in the
Goodrich FQIS. We have determined
this concern requires corrective action
in accordance with the SFAR 88
corrective action decision policy
discussed previously. We disagree with
the request to revise this SNPRM to
eliminate any requirement for corrective
action for airplanes equipped with a
Goodrich FQIS because we have
determined that an unsafe condition
requiring corrective action exists on the
Goodrich FQIS-equipped airplanes even
after considering the differences
between the Goodrich FQIS and the
original 757 system developed by
another manufacturer. We have not
changed this SNPRM regarding this
issue.
Request To Clarify Affected Tanks
FedEx requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
clarify that only the center fuel tank is
affected. FedEx stated that the proposed
wording could be interpreted as
applying to all tanks.
We agree to clarify the intent of this
SNPRM. The FQIS wiring and related
system components are to be modified
to the extent necessary to prevent the
development of an ignition source in the
center fuel tank due to FQIS failure
conditions. If modification of wing tankrelated components is necessary to
prevent an ignition source in the center
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fuel tank (for example, because of
common wiring between the tanks),
then that modification would be
required. Paragraph (g) of this SNPRM
already states this (‘‘modify the FQIS
wiring or fuel tank systems to prevent
development of an ignition source
inside the center fuel tank’’). A change
to this SNPRM itself therefore is not
necessary.
Request To Revise Proposed AD
Requirements To Apply to All Fuel
Tanks
NATCA noted that action similar to
the proposed requirements of the NPRM
(77 FR 12506, March 1, 2012) was
required for all fuel tanks on early
Model 747 and 737 airplanes via AD
98–20–40, Amendment 39–10808 (63
FR 52147, September 30, 1998); and AD
99–03–04, Amendment 39–11018 (64
FR 4959, February 2, 1999). The
commenter also noted that the FAA’s
published SFAR 88 unsafe condition
criteria (section 25.981(a)(3) of the
Federal Aviation Regulations (14 CFR
25.981(a)(3)) (https://www.faa.gov/
regulations_policies/advisory_circulars/
index.cfm/go/document.information/
documentID/73716)) require corrective
action for ‘‘known latent-plus-one
conditions’’ in both low- and highflammability tanks.
We infer the commenter is requesting
that we revise the proposed actions of
the NPRM (77 FR 12506, March 1, 2012)
to apply to all fuel tanks. We disagree.
NATCA’s interpretation of the word
‘‘known’’ appears to be different from
that intended by the FAA when the
SFAR 88 decision criteria were
developed and implemented. For lowflammability fuel tanks, the FAA has
proposed that corrective action for
‘‘latent-plus-one’’ issues be required
only in cases where the particular
latent-plus-one scenario is known to
have occurred on that particular design.
Where relevant design details are
significantly different, a condition that
has occurred with one design is not
considered to be a ‘‘known’’ latent-plusone condition on another design simply
because the same architectural
vulnerability theoretically exists.
In the case of AD 98–20–40,
Amendment 39–10808 (63 FR 52147,
September 30, 1998); and AD 99–03–04,
Amendment 39–11018 (64 FR 4959,
February 2, 1999); we required
corrective action for all fuel tanks
because the details of those designs
were identical or very similar to the
details of the design that were
considered to be the most likely cause
of the 1996 Model 747–100 accident.
The actions of AD 98–20–40 and AD
99–03–04 are consistent with the intent
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Fmt 4702
Sfmt 4702
of the later-developed SFAR 88 unsafe
condition criteria. We have not changed
this SNPRM regarding this issue.
Request for Specific Corrective Action
EASA noted that the NPRM (77 FR
12506, March 1, 2012) did not cite
service information for a specific design
solution other than acknowledging FRM
as an acceptable method of compliance.
We infer that EASA is requesting that
the NPRM propose to require a specific
corrective action for the unsafe
condition. EASA pointed out that,
under its regulations and policies,
EASA issues ADs based on specific
solutions provided by the responsible
manufacturer. EASA stated that, in the
absence of a specific solution, EASA
will not be in a position to simply adopt
the FAA AD, and may need to develop
its own AD or find another solution.
We disagree with the request to
require a specific corrective action in
this SNPRM. In this case, the
manufacturer has not provided a
corrective action specific to FQIS in
time to support the NPRM, noting that
they have provided service instructions
to install FRM that the FAA has defined
as one method of compliance within the
NPRM (77 FR 12506, March 1, 2012).
While the FAA has the authority to
compel the manufacturer to provide a
solution specifically providing FQIS
protection, in this case the FAA decided
to seek public comment on the NPRM
(77 FR 12506, March 1, 2012) before
deciding whether to take that action.
The FAA already requires the vast
majority of passenger airplanes
registered in the U.S. to be equipped
with FRM, and since we defined
incorporation of FRM as one method of
compliance within the NPRM (77 FR
12506, March 1, 2012), and because
Boeing and Goodrich provided
information to show that a specific FQIS
protection solution would have a perairplane cost similar to that of Boeing’s
FRM design solution, we have
determined there is no practical reason
to require the manufacturer to provide
a corrective action specific to FQIS for
passenger airplanes. Consideration of
the many comments on the NPRM (77
FR 12506, March 1, 2012) has resulted
in a revision of the FAA’s approach for
cargo airplanes, leading to a
significantly different proposed AD. At
this point we do expect the
manufacturer to provide service
information for the proposed optional
solution for cargo airplanes. We have,
however, decided not to further delay
action on this issue by waiting for that
service information. The service
information is expected to be released
shortly after the issuance of a final rule.
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No change to this SNPRM is necessary
for this issue. If service information
becomes available before the final rule
is issued, we might consider
incorporating it into the AD.
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Request for Information on
Modifications
Icelandair requested more detailed
information on the specific
modifications that would need to be
performed to comply with the proposed
requirements specified in the NPRM (77
FR 12506, March 1, 2012), and asked if
a related service bulletin was available.
Service information is available for
incorporation of FRM approved by the
FAA as compliant with the FTFR rule
(73 FR 42444, July 21, 2008)
requirements of section 26.33(c)(1) of
the Federal Aviation Regulations (14
CFR 26.33(c)(1)).
As stated previously, we have revised
the NPRM (77 FR 12506, March 1, 2012)
to provide more specific information
about a less costly optional modification
for cargo airplanes. Service information
related to this modification is not
currently available. We have not
changed this SNPRM further regarding
this issue.
Request for Optional Modification
Goodrich requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
require or allow a modification to
separate and shield the FQIS tank-side
circuits from other wiring as corrective
action for the identified unsafe
condition. Goodrich referred to its
discussion regarding the capability of
the Goodrich FQIS processor to isolate
the tank-side circuits from the non-tankside circuits.
We partially agree with the request.
We considered that method of
compliance and determined that the
benefit from that corrective action
would be sufficient for cargo airplanes
when combined with regular FQIS
checks using the previously mentioned
built-in test capability. We disagree with
allowing the proposed alternative for
passenger airplanes that are not
equipped with FRM because the level of
risk reduction achieved from that
alternative corrective action would not
provide a sufficient risk reduction for
those airplanes. Even when the built-in
test capability is periodically exercised,
there will still be a significant latency
period for some in-tank failures. The
risk on the flights where those failures
exist and where flammable conditions
exist in the fuel tank is considered to be
excessive for passenger airplanes,
because it results from a single
additional failure (those flights would
not be fail-safe). Even if it did not result
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from an additional single failure, it
would still exceed the TARAMallowable risk level for individual flight
risk. This determination is consistent
with the SFAR 88 corrective action
decision policy and TARAM policy. As
discussed previously, we have added
new paragraph (h) in this SNPRM to
allow the option of a periodic BITE
check and partial wire separation for
cargo airplanes.
Request for Repetitive Inspections or
Replacement
Oy Air Finland Ltd. stated that wires
within the fuel tank must remain in an
undamaged condition and therefore
requested that we revise the NPRM (77
FR 12506, March 1, 2012) to specify
their repetitive inspection or
replacement. The commenter provided
no justification.
We disagree with including specific
requirements to periodically inspect or
replace the wiring within the fuel tanks
because airworthiness limitations and
existing maintenance practices are
already in place to monitor the
condition of in-tank wiring. This
SNPRM would require installation of
flammability reduction means or a
combination of periodic system checks
(which would detect many types of
wiring defects or damage) and wire
separation improvements, either of
which would significantly reduce the
probability of a fuel tank explosion on
a given airplane flight to an acceptable
level. We have not changed this SNPRM
regarding this issue.
Request To Compel Issuance of Service
Information
NATCA requested that we enforce
sections 21.99 and 183.63(d) of the
Federal Aviation Regulations (14 CFR
21.99 and 183.63(d)) and SFAR 88,
Amendment 21–78, and subsequent
Amendments 21–82 and 21–83) (https://
rgl.faa.gov/Regulatory_and_Guidance_
Library%5CrgFAR.nsf/0/EEFB3F9445
1DC06286256C93004F5E07?Open
Document) to obtain necessary service
information from design approval
holders. NATCA noted that EASA
cannot ‘‘issue ADs’’ (that is, EASA may
not be able to adopt the FAA AD per se)
if specific service information is not
identified. NATCA expressed concern
that other civil aviation authorities may
take a similar position.
We partially agree with the request.
We agree that the cited regulations are
relevant in setting requirements for
action by design approval holders when
we have identified an unsafe condition.
We also recognize that issuance of an
AD without service information creates
significant issues for regulatory agencies
PO 00000
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9409
and for operators that must comply with
the AD. This SNPRM, however, is not
the appropriate forum to discuss
potential enforcement action. We have
not changed this SNPRM regarding this
issue.
Boeing’s Planned Service Information
Boeing stated that it will offer only
the Boeing FRM as a solution, if the AD
is issued as proposed. Boeing added that
it does not develop detailed cost
estimates for design changes they do not
intend to provide. Further, Boeing
stated that it does not advocate FRM
installation on airplanes for which FRM
is not required under the FTFR rule
(‘‘Reduction of Fuel Tank Flammability
in Transport Category Airplanes’’ (73 FR
42444, July 21, 2008)). Boeing proposed
no change to the NPRM (77 FR 12506,
March 1, 2012). Boeing noted that a
requirement to install an FRM on the
affected airplanes could not be justified
in the cost-versus-benefit analysis
performed for the new FTFR rule, and
therefore cannot be justified to address
the unsafe condition identified by the
FAA.
We have provided the basis for this
SNPRM in response to ‘‘Request for
Cost-Benefit Analysis’’ in this SNPRM.
We emphasize, however, that this
SNPRM does not require installation of
a nitrogen generation system or other
FRM. The actions specified in this
SNPRM will correct a specific, known
unsafe condition with the FQIS. We
decided to propose this AD action
without specific service information for
the expected design solution
specifically because Boeing has not to
date provided a design solution specific
to FQIS. As a result of considering the
comments to the NPRM (77 FR 12506,
March 1, 2012), the FAA has identified
a less costly option for Model 757 cargo
airplanes. We have asked Boeing to
develop service information for that
option, and Boeing has agreed. Since the
FAA already requires the vast majority
of passenger airplanes registered in the
U.S. to be equipped with FRM and we
defined incorporation of FRM as one
method of compliance within the NPRM
(77 FR 12506, March 1, 2012), and
because Boeing and Goodrich provided
information to show that a specific FQIS
protection solution would have a perairplane cost similar to that of Boeing’s
FRM design solution, we have
determined there is no practical reason
to require the manufacturer to provide
a corrective action specific to FQIS for
passenger airplanes. We have not
further changed this SNPRM regarding
this issue.
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Request To Extend Compliance Time
Pending Issuance of Service
Information
A4A requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
extend the compliance time from 60
months to ‘‘a 96-month compliance
period that commences one year after
the effective date of the AD’’—for a total
compliance time of 9 years. A4A noted
that SFAR 88 (Special Federal Aviation
Regulation No. 88 (‘‘SFAR 88,’’
Amendment 21–78, and subsequent
Amendments 21–82 and 21–83) (https://
rgl.faa.gov/Regulatory_and_Guidance_
Library%5CrgFAR.nsf/0/EEFB3F94
451DC06286256C93004F5E07?Open
Document)) required design solutions
for non-compliant designs to be
provided by December 6, 2002, and
considered that the absence of service
information reflects a failure of
communication and coordination,
presumably between the FAA and
Boeing. A4A was concerned that
Boeing’s declaration that it does not
intend to develop a design solution
other than its existing nitrogen
generation system indicates that the
development of any other design
solution would be technically
challenging and time consuming. A4A
also cited the implementation of the
requirements of part 26 of the Federal
Aviation Regulations (14 CFR part 26) as
an example of the FAA underestimating
the costs and time required to develop
design solutions.
We partially agree with the request to
extend the compliance time. While we
agree to provide additional time for
manufacturers to develop service
information, we acknowledge that
service information is not likely to be
available until several months after the
final rule is issued. We disagree with
the assertion that the delay in proposing
an AD to address the FQIS latent-plusone unsafe conditions on several
transport airplane models reflects a
failure to communicate and coordinate
with design approval holders.
In 2003, the FAA held a series of AD
board meetings to decide which of the
design areas identified in SFAR 88
design reviews as non-compliant on
Boeing airplanes would be classified as
unsafe conditions requiring AD action.
The FQIS latent-plus-one issue was
identified as an unsafe condition for
high flammability fuel tanks at that time
for several models, including the Model
757. Several airplane models from other
manufacturers were identified as having
similar issues. However, during that
same time period, the National
Transportation Safety Board (NTSB) had
recommended FAA action to require
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inerting systems for center fuel tanks,
and the FAA was working with industry
to develop a practical nitrogen
generation system for new production
and retrofit installations on transport
airplanes. The FAA was also planning
to propose a new rule requiring those
systems to be installed on new and
existing airplanes, as recommended by
the NTSB. The FAA recognized that, if
such a system was installed on a given
set of airplanes, the unsafe condition
determination for the center fuel tank
latent-plus-one would be addressed due
to the modified center fuel tank meeting
the conditions for a low flammability
fuel tank after installation of a nitrogen
generation system.
The FAA therefore decided to defer
addressing the FQIS latent-plus-one
issue on the affected airplanes until
after the outcome of the FTFR
rulemaking process. Now that the
rulemaking process is complete and the
safety enhancement provided by the
FTFR rule (73 FR 42444, July 21, 2008)
has been limited to certain airplanes (14
CFR part 121, 125, and 129 passenger
airplanes), the FAA is addressing the
FQIS latent-plus-one unsafe conditions
on the airplanes that are not required to
receive the safety enhancement of the
FTFR rule. This history was discussed
in detail in the NPRM (77 FR 12506,
March 1, 2012) and in the preamble for
the FTFR rule.
We disagree with extending the
compliance time to 9 years. Service
information to support the modification
portion of the option for cargo airplanes
is expected to be available shortly after
the final rule is issued. The service
information for the inspection portion of
that option and the FRM option is
already released. We have determined
that a compliance time extension to 72
months for the modification will give
adequate time for manufacturers to
complete the remaining service
information and for operators to
complete the modification.
We have revised the compliance time
in this SNPRM to 72 months after the
effective date of the AD.
Request To Reduce Compliance Time
NATCA requested that we reduce the
compliance time from 60 months to 36
months because of the time that has
already passed to address this unsafe
condition since its identification in
2003.
While we acknowledge the time that
has passed since the identification of
the unsafe condition identified in this
SNPRM, the FAA delayed taking action
for this issue while we developed the
FTFR rule (73 FR 42444, July 21, 2008),
determined its applicability, which
PO 00000
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Fmt 4702
Sfmt 4702
directly affected the applicability of this
SNPRM, and implemented the FTFR
rule. Now that we are proposing action
for the affected airplanes, we must
consider the ability of industry to
develop an appropriate design change
and incorporate it on all affected
airplanes; we find that it is not practical
for industry to respond to this AD in
only 3 years. We have therefore not
reduced the compliance time in this
SNPRM.
Request To Revise Cost Estimate Based
on New Data
Boeing requested that we revise the
cost estimate specified in the NPRM (77
FR 12506, March 1, 2012) because the
actual cost to develop and implement a
design change to fully address the FQIS
latent-plus-one failure conditions would
be significantly higher. Boeing
estimated in their comment that the cost
to develop and implement a transient
suppression unit design for Model 757
airplanes would be about the same as
the cost of Boeing’s FRM provided for
the airplanes affected by the FTFR rule
(73 FR 42444, July 21, 2008): in excess
of $300,000 per airplane for airplanes
equipped with the early FQIS design,
and in excess of $200,000 per airplane
for airplanes equipped with a Goodrich
FQIS.
In a subsequent meeting initiated by
the FAA to obtain more detail on this
cost estimate, Boeing provided a higher
cost estimate than they provided in their
written comment. However, in
subsequent discussions with Boeing as
part of developing this SNPRM, Boeing
indicated that they were working on an
isolation-based design alternative to the
FAA’s proposed modification option for
the cargo airplanes that would likely be
significantly less costly than the FAA’s
proposed cargo airplane option of
partial wire separation.
We partially agree with the
commenter. We agree to revise the cost
estimate because both Boeing and one of
Boeing’s affected FQIS vendors
provided similar cost estimates that
were higher than the estimates made in
the NPRM (77 FR 12506, March 1, 2012)
by the FAA. We disagree to revise the
cost estimate as Boeing proposed. We
have received several inconsistent cost
estimates from industry during the
development of the FTFR rule (73 FR
42444, July 21, 2008), in their written
comments to the NPRM, and during
discussions of the FAA’s proposed
alternative for cargo airplanes. We have
therefore provided a revised cost
estimate for the originally proposed
action based on input from Boeing’s
written comment and from the FQIS
vendor. We also have considered that it
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is likely that aftermarket vendors may
develop competing design solutions, as
has occurred for other similar ADs, and
those solutions will likely cost less than
the original manufacturer’s solutions.
In addition, we have identified an
additional compliance option—with a
different cost—for cargo airplanes. That
cost estimate is based on Model 757
service information that described a
very similar modification. We have used
the work-hour estimate from that service
bulletin, increased the work-hour
estimate by 20 percent to account for
any unforeseen increases in the work,
and increased the parts prices to
account for inflation and the potential
that additional parts may be needed.
Request To Revise Cost Estimate Based
on AD Scope
Goodrich requested that, if the intent
of the NPRM (77 FR 12506, March 1,
2012) is to protect all fuel tanks rather
than just the center fuel tank, we revise
the cost estimate of the NPRM
accordingly. Goodrich stated that the
cost estimate is based on three
assumptions: (1) That current
technology circuit isolation devices
similar to those previously approved for
other models would be acceptable, (2)
that no further changes to airplane
wiring would be required, and (3) that
the design change would be required to
protect only the center fuel tank.
Goodrich noted that protection for all
fuel tanks is required for the two similar
ADs: AD 99–03–04, Amendment 39–
11018 (64 FR 4959, February 2, 1999),
for Model 737 airplanes; and AD 98–20–
40, Amendment 39–10808 (63 FR
52147, September 30, 1998), for Model
747 airplanes. Goodrich requested that
we revise the cost estimate if the AD’s
intent is to require protection for fuel
tanks other than the center fuel tank or
if other wiring change requirements are
anticipated. Goodrich stated that the
cost specified in the NPRM should be
estimated based on the actual design
changes expected, rather than on
previous AD actions.
We provide the following clarification
of the intended scope of the NPRM (77
FR 12506, March 1, 2012) and the
associated cost estimate regarding
which fuel tanks are subject to the
proposed requirements. AD 99–03–04,
Amendment 39–11018 (64 FR 4959,
February 2, 1999), and AD 98–20–40,
Amendment 39–10808 (63 FR 52147,
September 30, 1998), affect FQIS
designs that are considered to have a
higher level of risk of a fuel tank
ignition source than the systems used
on Model 757 airplanes. In addition,
those systems were identical or nearly
identical to the FQIS that was
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determined by the NTSB to be the most
likely cause of the 1996 Model 747–100
accident described in the NPRM.
Because the latent-plus-one failure
scenario was suspected of actually
having occurred on that system type, we
determined that corrective action for all
fuel tanks was appropriate. This
decision was consistent with the
subsequently published FAA policy on
SFAR 88 AD decision criteria (section
25.981(a)(3) of the Federal Aviation
Regulations (14 CFR 25.981(a)(3)))
(https://www.faa.gov/regulations_
policies/advisory_circulars/index.cfm/
go/document.information/documentID/
73716)). Also, it was our understanding
that the design of that FQIS was such
that, due to wiring interconnections
between fuel tanks, it was necessary to
protect the circuits for all fuel tanks in
order to achieve effective protection for
any one fuel tank.
We have determined that the FQIS
used on earlier production Model 757
airplanes has the same fuel tank
interconnection issue, but that the
Goodrich system used on later
production Model 757 airplanes does
not have that issue. Since the cost
estimates provided by both Boeing and
Goodrich were based on design
solutions that included upgrading to a
Goodrich FQIS, we assume that the
level of circuit protection for the center
fuel tank can be significantly increased
relative to the existing Goodrich design
without having to further alter circuits
or wiring for the main fuel tanks
(beyond the alterations necessary to
replace the FQIS with the Goodrich
FQIS).
Because the latent-plus-one scenarios
for Model 757 airplanes equipped with
the Goodrich FQIS are classified as
‘‘theoretical’’ rather than ‘‘known to
have occurred’’ under the FAA policy
on SFAR 88 AD decision criteria
(section 25.981(a)(3) of the Federal
Aviation Regulations (14 CFR
25.981(a)(3))) (https://www.faa.gov/
regulations_policies/advisory_circulars/
index.cfm/go/document.information/
documentID/73716)), we have
determined in accordance with that
policy that the corrective action for
passenger airplanes must eliminate the
potential for all theoretical latent-plusone scenarios to create an ignition
source in the center fuel tank, which is
classified under that policy as a high
flammability fuel tank. The need to
modify the circuits or wiring for the
main fuel tanks to achieve that intent
will depend on the proposed design
solution and the existing configuration
of the airplane.
As stated previously, we have revised
the cost estimate in this SNPRM. For the
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9411
purpose of the cost estimate for
passenger airplanes, we have assumed
that the airplane will be upgraded to the
Goodrich FQIS if necessary, and any
further modifications will be to only the
center fuel tank circuits or wiring. For
the purpose of the additional proposed
cargo airplane option, we have provided
separate estimates for each design. For
cargo airplanes equipped with the early
757 FQIS design, we have assumed that
additional isolation of some main fuel
tank wiring will be required. It is not
necessary to change the proposed
requirement itself in paragraph (g) of
this SNPRM, which is very specific that
protection is required for the center fuel
tank.
Request To Revise Cost Estimate To
Consider Long-Term Effect of AD
Goodrich asked whether the cost
estimate specified in the NPRM (77 FR
12506, March 1, 2012) considers the
expectation that the affected fleet will
be in operation for at least 20 more
years, and that a complete redesign of
the FQIS would need to be considered
to ensure the availability of key FQIS
electrical components. Goodrich stated
this concern could drive potential
development costs higher.
We agree with the commenter’s
assertion. We did consider that the
affected fleet will be in service for a
considerable period of time. In the cost
estimate in the NPRM (77 FR 12506,
March 1, 2012), we assumed that the
existing FQIS could be modified to meet
the intent of the AD. However,
comments from Boeing and Goodrich
led us to recognize that it was likely that
operators of airplanes with the early 757
FQIS design will likely need to be
upgraded to the later Goodrich FQIS.
The cost estimates used in this SNPRM
for the fully compliant FQIS option (as
opposed to the newly added cargo
airplane option) are based on the
estimates provided by Boeing and
Goodrich. We previously described
changes to the cost estimate in this
SNPRM, but no further change is
necessary regarding this issue.
Request To Explain Delay in
Rulemaking and Identify Planned
SFAR 88 ADs
A4A requested that we explain the
delay in rulemaking for this issue, and
identify any further planned SFAR 88
ADs. A4A asked why the NPRM (77 FR
12506, March 1, 2012) was issued
approximately 10 years after the
identification of the unsafe conditions
and development of design solutions
was required to be completed under
SFAR 88. A4A further asked that the
FAA provide information on any other
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designs that were already reviewed
under SFAR 88, and provide industry
with information regarding their
planned disposition.
We have specifically discussed these
issues in the preamble to the FTFR rule
(73 FR 42444, July 21, 2008) and the
NPRM (77 FR 12506, March 1, 2012),
and explained the reasons for the delay
in the response to ‘‘Request to Extend
Compliance Time Pending Issuance of
Service Information’’ in this SNPRM.
We cannot provide additional
information on the results of design
reviews and the planned disposition of
issues identified in those design reviews
because that information is proprietary.
The FAA has not made available to the
public an overall list of the specific
product issues identified and the plans
to address those issues, but operators
can request the design review results
from the manufacturers. We will likely
propose additional AD rulemaking, and
the public will be notified of those
proposals via NPRMs. We have not
changed this SNPRM regarding this
issue.
Request for Independent Review
Regarding Timeliness of AD
Request To Explain Timing of NPRM
(77 FR 12506, March 1, 2012) and
Deficiencies of Affected Design
FedEx requested that we explain what
is non-compliant about the affected
design and why we are proposing this
design change at this late date. FedEx
stated that Boeing and Goodrich
determined in their safety reviews that
only the FQIS densitometer was noncompliant.
We agree to provide further
explanation. This SNPRM addresses the
question about the timing of this
proposal under ‘‘Request to Extend
Compliance Time Pending Issuance of
Service Information’’ in this SNPRM.
Boeing and Goodrich did identify that
the densitometer of the Goodrich system
had the potential for a single failure to
cause an ignition source in a fuel tank.
That issue was addressed by AD 2009–
06–20, Amendment 39–15857 (74 FR
12236, March 24, 2009). However, the
Boeing safety review and the FAA SFAR
88 AD Board also identified the
potential for a failure in airplane wiring
outside the fuel tank or in the FQIS
processor unit that, combined with a
pre-existing latent failure of wiring or
certain types of probe contamination
inside the fuel tank, could cause an
ignition source. These identified failure
combinations were considered to be
non-compliant with section 25.901(c) of
the Federal Aviation Regulations (14
CFR 25.901(c)) and section 25.981 of the
Federal Aviation Regulations (14 CFR
25.981). We have not changed this
SNPRM regarding this issue.
A4A requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
clarify that the compliance deadlines in
the AD prevail over the compliance
deadlines in section 121.1117 of the
Federal Aviation Regulations (14 CFR
121.1117) for any airplane for which the
operator has chosen to comply with the
AD by installing FRM.
The proposed compliance times
reflect the desired interpretation of the
commenter as they pertain to cargo
airplanes and airplanes that are not
operated per part 121, part 125, or part
129 of the Federal Aviation Regulations
(14 CFR part 121, 14 CFR part 125, or
14 CFR part 129). Passenger airplanes
operating under part 121, part 125, or
part 129 of the Federal Aviation
Regulations (14 CFR part 121, 14 CFR
part 125, or 14 CFR part 129) must meet
the compliance deadlines established in
those operating rules. No change to this
SNPRM is necessary regarding this
issue.
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NATCA requested an independent
review to identify and document how
this issue was allowed to go
unaddressed for 16 years since the TWA
accident and 9 years since SFAR 88
required the development of service
information. The commenter requested
that the findings from that review be
published.
We acknowledge that there have been
significant delays in addressing the
issue that is the subject of this SNPRM.
We are also fully aware of the events
and factors that have led to those delays.
We infer that NATCA made the request
to ensure that the public is aware of
those events and factors. We have
described those events and factors in the
NPRM (77 FR 12506, March 1, 2012)
and in the other comment responses
included in this SNPRM, and therefore
the FAA does not plan to conduct the
proposed review. We have not changed
this SNPRM regarding this issue.
Request To Clarify Compliance Times
Request To Clarify Master Minimum
Equipment List (MMEL) Relief
A4A requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
clarify that the MMEL relief provided
for the Boeing NGS also applies to
airplanes for which the operator has
chosen to comply with the AD by
installing an FRM such as the Boeing
NGS.
We acknowledge the commenter’s
concern. The revised applicability
statement in paragraph (c) of this
SNPRM excludes airplanes that are
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Fmt 4702
Sfmt 4702
‘‘equipped with a flammability
reduction means (FRM) approved by the
FAA. . . .’’ That exclusion does not
state that the installed equipment must
be operative. However, installed
equipment is required to be operative by
sections 121.628, 125.201, and 129.14 of
the Federal Aviation Regulations (14
CFR 121.628, 14 CFR 125.201, and 14
CFR 129.14) except as allowed by the
MMEL and the operator’s approved
minimum equipment list (MEL).
Dispatch with an inoperative FRM
under the MMEL is not prohibited by
the AD, and our intent is to allow such
operation. We have not further changed
this SNPRM regarding this issue.
Request To Clarify Airplanes Excluded
From Applicability
A4A requested that we revise the
NPRM (77 FR 12506, March 1, 2012) to
clarify that airplanes equipped with
FRM before conversion to all-cargo
operations are excluded from the
proposed requirement to modify the
FQIS.
We agree to provide clarification. The
revised applicability of this SNPRM
excludes airplanes for which operators
have installed FRM. No further change
is necessary to this SNPRM regarding
this issue. As noted above, the FRM
must be operational with the exception
of any relief granted under MMEL
provisions.
Additional Change to NPRM (77 FR
12506, March 1, 2012)
We have removed NOTE 1 of the
NPRM (77 FR 12506, March 1, 2012).
The note was included only as reminder
that maintenance and/or preventive
maintenance under 14 CFR part 43 is
permitted provided the maintenance
does not result in changing the ADmandated configuration (reference 14
CFR 39.7).
FAA’s Determination
We are proposing this SNPRM
because we evaluated all the relevant
information and determined the unsafe
condition described previously is likely
to exist or develop in other products of
the same type design. Certain changes
described above expand the scope of the
NPRM (77 FR 12506, March 1, 2012). As
a result, we have determined that it is
necessary to reopen the comment period
to provide additional opportunity for
the public to comment on this SNPRM.
Proposed Requirements of the SNPRM
This SNPRM would require
modifying the FQIS wiring or fuel tank
systems to prevent development of an
ignition source inside the center fuel
tank.
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Federal Register / Vol. 80, No. 35 / Monday, February 23, 2015 / Proposed Rules
Costs of Compliance
This estimate includes 148 cargo
airplanes and 19 non-air-carrier
passenger airplanes. We estimate the
We estimate that this proposed AD
affects 167 airplanes of U.S. registry.
Action
9413
following costs to comply with this
proposed AD:
Labor cost
Parts cost
Cost per product
Estimated Costs—Basic Proposed Requirement for All Airplanes
Fully correct FQIS vulnerability to latent-plus-one
failure conditions.
1,200 work-hours × $85 per hour = $102,000 .....
$200,000
$302,000.
$323,000
$384,200.
Estimated Costs—Optional Actions for All Airplanes
Install FRM ............................................................
720 work-hours × $85 per hour = $61,200 ..........
Estimated Costs—Optional Actions for Cargo Airplanes
Wire separation .....................................................
FQIS BITE check (required with wire separation
option).
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Existing regulations already require
that air-carrier passenger airplanes be
equipped with FRM by December 26,
2017. We therefore assume that the FRM
installation specified in paragraph (g) of
this SNPRM would be done on only the
19 affected non-air-carrier passenger
airplanes, for an estimated passenger
fleet cost of $5,738,000. We also assume
that the operators of the 148 affected
cargo airplanes would choose the less
costly actions specified in paragraph (h)
of this AD, at an estimated cost of
$4,373,400 for the wire separation
modification, plus $50,320 annually for
the BITE checks.
Authority for This Rulemaking
Title 49 of the United States Code
specifies the FAA’s authority to issue
rules on aviation safety. Subtitle I,
section 106, describes the authority of
the FAA Administrator. ‘‘Subtitle VII:
Aviation Programs’’ describes in more
detail the scope of the Agency’s
authority.
We are issuing this rulemaking under
the authority described in Subtitle VII,
Part A, Subpart III, Section 44701:
‘‘General requirements.’’ Under that
section, Congress charges the FAA with
promoting safe flight of civil aircraft in
air commerce by prescribing regulations
for practices, methods, and procedures
the Administrator finds necessary for
safety in air commerce. This regulation
is within the scope of that authority
because it addresses an unsafe condition
that is likely to exist or develop on
products identified in this rulemaking
action.
Regulatory Findings
We determined that this proposed AD
would not have federalism implications
under Executive Order 13132. This
proposed AD would not have a
substantial direct effect on the States, on
VerDate Sep<11>2014
13:55 Feb 20, 2015
Jkt 235001
230 work-hours × $85 per hour = $19,550 ..........
1 work-hour × $85 per hour = $85 .......................
$10,000
0
$29,550.
$85 per check (4 checks
per year).
the relationship between the national
Government and the States, or on the
distribution of power and
responsibilities among the various
levels of government.
For the reasons discussed above, I
certify this proposed regulation:
(1) Is not a ‘‘significant regulatory
action’’ under Executive Order 12866,
(2) Is not a ‘‘significant rule’’ under
the DOT Regulatory Policies and
Procedures (44 FR 11034, February 26,
1979),
(3) Will not affect intrastate aviation
in Alaska, and
(4) Will not have a significant
economic impact, positive or negative,
on a substantial number of small entities
under the criteria of the Regulatory
Flexibility Act.
(a) Comments Due Date
We must receive comments by April 24,
2015.
List of Subjects in 14 CFR Part 39
(e) Unsafe Condition
This AD was prompted by fuel system
reviews conducted by the manufacturer. We
are issuing this AD to prevent development
of an ignition source inside the center fuel
tank caused by a latent in-tank failure
combined with electrical energy transmitted
into the center fuel tank via the fuel quantity
indicating system (FQIS) wiring due to a
single out-tank failure.
Air transportation, Aircraft, Aviation
safety, Incorporation by reference,
Safety.
The Proposed Amendment
Accordingly, under the authority
delegated to me by the Administrator,
the FAA proposes to amend 14 CFR part
39 as follows:
PART 39—AIRWORTHINESS
DIRECTIVES
1. The authority citation for part 39
continues to read as follows:
■
Authority: 49 U.S.C. 106(g), 40113, 44701.
§ 39.13
[Amended]
2. The FAA amends § 39.13 by adding
the following new airworthiness
directive (AD):
■
The Boeing Company: Docket No. FAA–
2012–0187; Directorate Identifier 2011–
NM–094–AD.
PO 00000
Frm 00015
Fmt 4702
Sfmt 4702
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company
Model 757–200, –200PF, –200CB, and –300
series airplanes; certificated in any category;
except airplanes equipped with a
flammability reduction means (FRM)
approved by the FAA as compliant with the
Fuel Tank Flammability Reduction (FTFR)
rule (73 FR 42444, July 21, 2008)
requirements of section 25.981(b) or section
26.33(c)(1) of the Federal Aviation
Regulations (14 CFR 25.981(b) or 14 CFR
26.33(c)(1)).
(d) Subject
Joint Aircraft System Component (JASC)
Code 7397: Engine fuel system wiring.
(f) Compliance
Comply with this AD within the
compliance times specified, unless already
done.
(g) Modification
Within 72 months after the effective date
of this AD, modify the FQIS wiring or fuel
tank systems to prevent development of an
ignition source inside the center fuel tank,
using a method approved in accordance with
the procedures specified in paragraph (i) of
this AD.
(h) Optional Actions for Cargo Airplanes
For airplanes used exclusively for cargo
operations: As an option to the requirements
of paragraph (g) of this AD, do the actions
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Federal Register / Vol. 80, No. 35 / Monday, February 23, 2015 / Proposed Rules
specified in paragraphs (h)(1) and (h)(2) of
this AD, using methods approved in
accordance with the procedures specified in
paragraph (i) of this AD.
(1) Within 6 months after the effective date
of this AD, record the existing fault codes
stored in the FQIS processor and then do a
BITE check (check of built-in test equipment)
of the FQIS, in accordance with the
Accomplishment Instructions of Boeing
Service Bulletin 757–28–0136, dated June 5,
2014. If any fault codes are recorded prior to
the BITE check or as a result of the BITE
check, before further flight, do all applicable
repairs and repeat the BITE check until a
successful test is performed with no faults
found, in accordance with Boeing Service
Bulletin 757–28–0136, dated June 5, 2014.
Repeat these actions thereafter at intervals
not to exceed 750 flight hours.
(2) Within 72 months after the effective
date of this AD, modify the airplane by
separating FQIS wiring that runs between the
FQIS processor and the center fuel tank,
including any circuits that might pass
through a main fuel tank, from other airplane
wiring that is not intrinsically safe.
(i) Alternative Methods of Compliance
(AMOCs)
(1) The Manager, Seattle Aircraft
Certification Office (ACO), FAA, has the
authority to approve AMOCs for this AD, if
requested using the procedures found in 14
CFR 39.19. In accordance with 14 CFR 39.19,
send your request to your principal inspector
or local Flight Standards District Office, as
appropriate. If sending information directly
to the manager of the ACO, send it to the
attention of the person identified in
paragraph (j) of this AD. Information may be
emailed to: 9-ANM-Seattle-ACO-AMOCRequests@faa.gov.
(2) Before using any approved AMOC,
notify your appropriate principal inspector,
or lacking a principal inspector, the manager
of the local flight standards district office/
certificate holding district office.
(j) Related Information
For more information about this AD,
contact Jon Regimbal, Aerospace Engineer,
Propulsion Branch, ANM–140S, FAA, Seattle
Aircraft Certification Office (ACO), 1601 Lind
Avenue SW., Renton, Washington 98057–
3356; phone: 425–917–6506; fax: 425–917–
6590; email: jon.regimbal@faa.gov.
Issued in Renton, Washington, on
December 18, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. 2015–03540 Filed 2–20–15; 8:45 am]
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BILLING CODE 4910–13–P
DEPARTMENT OF EDUCATION
34 CFR Chapter VI
Proposed Priorities, Requirements,
Selection Criterion, and Definitions—
First in the World Program
CFDA Numbers: 84.116F and 84.116X
VerDate Sep<11>2014
13:55 Feb 20, 2015
Jkt 235001
Office of Postsecondary
Education, Department of Education.
ACTION: Proposed priorities,
requirements, selection criterion, and
definitions.
AGENCY:
The Assistant Secretary for
Postsecondary Education proposes
priorities, requirements, a selection
criterion, and definitions under the First
in the World (FITW) Program. The
Assistant Secretary may use these
priorities, requirements, selection
criterion, and definitions for FITW
competitions in fiscal year (FY) 2015
and later years. These priorities,
requirements, selection criterion, and
definitions would enable the
Department to focus the FITW program
on identified barriers to student success
in postsecondary education and
advance the program’s purpose to build
evidence for what works in
postsecondary education through
development, evaluation, and
dissemination of innovative strategies to
support students who are at risk of
failure in persisting in and completing
their postsecondary programs of study.
DATES: We must receive your comments
on or before March 25, 2015.
ADDRESSES: Submit your comments
through the Federal eRulemaking Portal
or via postal mail, commercial delivery,
or hand delivery. We will not accept
comments submitted by fax or by email
or those submitted after the comment
period. To ensure that we do not receive
duplicate copies, please submit your
comments only once.
• Federal eRulemaking Portal: Go to
www.regulations.gov to submit your
comments electronically. Information
on using Regulations.gov, including
instructions for accessing agency
documents, submitting comments, and
viewing the docket, is available on the
site under ‘‘Are you new to the site?’’
• Postal Mail, Commercial Delivery,
or Hand Delivery: If you mail or deliver
your comments about these proposed
regulations, address them to Frank
Frankfort, U.S. Department of
Education, 1990 K Street NW., Room
6166, Washington, DC 20006.
Privacy Note: The Department’s
policy is to make all comments received
from members of the public available for
public viewing in their entirety on the
Federal eRulemaking Portal at
www.regulations.gov. Therefore,
commenters should be careful to
include in their comments only
information that they wish to make
publicly available.
FOR FURTHER INFORMATION CONTACT:
Frank Frankfort. Telephone: (202) 502–
7513 or email: frank.frankfort@ed.gov.
SUMMARY:
PO 00000
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Fmt 4702
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If you use a telecommunications
device for the deaf (TDD) or a text
telephone (TTY), call the Federal Relay
Service (FRS), toll free, at 1–800–877–
8339.
SUPPLEMENTARY INFORMATION:
Invitation to Comment: We invite you
to submit comments regarding this
notice. To ensure that your comments
have maximum effect in developing the
notice of final priorities, requirements,
selection criterion, and definitions, we
urge you to identify clearly the specific
proposed priority, requirement,
selection criterion or definition that
each comment addresses.
We invite you to assist us in
complying with the specific
requirements of Executive Orders 12866
and 13563 and their overall requirement
of reducing regulatory burden that
might result from these proposed
priorities, requirements, selection
criterion, or definitions. Please let us
know of any further ways we could
reduce potential costs or increase
potential benefits while preserving the
effective and efficient administration of
the program.
During and after the comment period,
you may inspect all public comments
about this notice by accessing
Regulations.gov. You may also inspect
the comments in person in room 6164,
1990 K. St. NW., Washington, DC
between the hours of 8:30 a.m. and 4:00
p.m., Washington, DC time, Monday
through Friday of each week except
Federal holidays. Please contact the
person listed under FOR FURTHER
INFORMATION CONTACT.
Assistance to Individuals with
Disabilities in Reviewing the
Rulemaking Record: On request we will
provide an appropriate accommodation
or auxiliary aid to an individual with a
disability who needs assistance to
review the comments or other
documents in the public rulemaking
record for this notice. If you want to
schedule an appointment for this type of
accommodation or auxiliary aid, please
contact the person listed under FOR
FURTHER INFORMATION CONTACT.
Purpose of Program: Earning a
postsecondary degree or credential is a
prerequisite for the growing jobs of the
new economy and the clearest pathway
to the middle class. Average earnings of
college graduates are almost twice as
high as that of workers with only a high
school diploma and, over this decade,
employment in jobs requiring education
beyond a high school diploma will grow
more rapidly than employment in jobs
that do not.1
1 Carnavale, A., Smith, N., Strohl, J., Help
Wanted: Projections of Jobs and Education
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Agencies
[Federal Register Volume 80, Number 35 (Monday, February 23, 2015)]
[Proposed Rules]
[Pages 9400-9414]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2015-03540]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2012-0187; Directorate Identifier 2011-NM-094-AD]
RIN 2120-AA64
Airworthiness Directives; the Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of
comment period.
-----------------------------------------------------------------------
SUMMARY: We are revising an earlier proposed airworthiness directive
(AD) for certain The Boeing Company Model 757 airplanes. The NPRM
proposed to require modifying the fuel quantity indication system
(FQIS) wiring or fuel tank systems to prevent development of an
ignition source inside the center fuel tank. The NPRM was prompted by
fuel system reviews conducted by the manufacturer. This action revises
the NPRM by revising the applicability, including optional actions for
cargo airplanes, and extending the compliance time. We are proposing
this supplemental NPRM (SNPRM) to prevent ignition sources inside the
center fuel tank, which, in combination with flammable fuel vapors,
could result in fuel tank explosions and consequent loss of the
airplane. Since these actions significantly change the corrective
action options for cargo airplanes relative to the proposal in the
NPRM, and because the cost estimate is significantly revised, we are
reopening the comment period to allow the public the chance to comment
on these proposed changes.
DATES: We must receive comments on this SNPRM by April 24, 2015.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
Fax: 202-493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
For service information identified in this AD, contact Boeing
Commercial Airplanes, Attention: Data & Services Management, P. O. Box
3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-5000,
extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.
You may view this referenced service information at the FAA, Transport
Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information
on the availability of this material at the FAA, call 425-227-1221. It
is also available on the Internet at https://www.regulations.gov by
searching for and locating Docket No. FAA-2012-0187.
Examining the AD Docket
You may examine the AD docket on the Internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2012-
0187; or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this proposed AD, the regulatory evaluation, any comments
received, and other information. The street address for the Docket
Office (phone: 800-647-5527) is in the ADDRESSES section. Comments will
be available in the AD docket shortly after receipt.
FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6506; fax: 425-917-6590; email: jon.regimbal@faa.gov.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include ``Docket No. FAA-2012-0187;
Directorate Identifier 2011-NM-094-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD because of those comments.
We will post all comments we receive, without change, to https://www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.
Discussion
We issued an NPRM to amend 14 CFR part 39 by adding an AD that
would apply to certain The Boeing Company Model 757 airplanes. The NPRM
published in the Federal Register on March 1, 2012 (77 FR 12506). The
NPRM proposed to require modifying the fuel quantity indication system
(FQIS) wiring or fuel tank systems to prevent development of an
ignition source inside the center fuel tank. We subsequently issued an
NPRM (77 FR 33129, June 5, 2012) to reopen and extend the comment
period for an additional 2 months.
Related Service Information Under 1 CFR Part 51
We have reviewed Boeing Service Bulletin 757-28-0136, dated June 5,
2014. This service information describes procedures for the built-in
test equipment test/procedure (BITE check) specified in paragraph
(h)(1) of this
[[Page 9401]]
supplemental NPRM. For information on the procedures and compliance
times, refer to this service information. This service information is
reasonably available; see ADDRESSES for ways to access this service
information.
Comments
We gave the public the opportunity to comment on the NPRM (77 FR
12506, March 1, 2012). The following presents the comments received on
the NPRM and the FAA's response to each comment.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): Unjustified by
Risk
Boeing and Airbus requested that we withdraw the NPRM (77 FR 12506,
March 1, 2012). Airbus requested that we consider risk levels before
pursuing anticipated ADs for similar models. Boeing's request was based
on a determination that the risk posed by the FQIS is not high enough
to warrant AD action. Boeing described the detailed design features
that it considers make the failures contributing to the unsafe
condition unlikely. Boeing added that its own numerical probability
analysis of the average risk level due to the combination of failures
required to cause a fuel tank explosion is on the order of one
catastrophic event per billion flight hours. Boeing pointed out that
this probability level would meet the certification standard for
systems contained in section 25.1309(b) of the Federal Aviation
Regulations (14 CFR 25.1309(b)). Boeing also pointed out that, because
the Model 757 is out of production and has a limited remaining fleet
life, the total risk of a catastrophic event occurring in the remaining
fleet life is approximately 0.5 percent. Boeing also noted that if a
conductive condition were to exist between the probes or wiring and
structure, it would be identified by FQIS faults and therefore would
not be latent for multiple flights.
We disagree with the request to withdraw the NPRM (77 FR 12506,
March 1, 2012). Average risk per flight hour and total fleet risk were
not the safety criteria that drove the FAA to propose the AD. In
addition to examining average risk and total fleet risk, the FAA
examines the individual flight risk on the worst reasonably anticipated
flights. FAA Transport Airplane Risk Assessment Methodology (TARAM)
Policy Statement PS-ANM-25-05 (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/4E5AE8707164674A862579510061F96B?OpenDocument&Highlight=ps-anm-25-05)
calls for the FAA to assess individual flight safety risk in
consideration of pre-existing hidden failure conditions and accounts
for dispatch with inoperative equipment. The TARAM policy classifies a
flight dispatch condition as ``reasonably anticipated'' if, in absence
of corrective action, ten or more flights are expected to occur.
Average risk is an arithmetic average of the risk of a given event
during all operation of an aircraft fleet, regardless of whether the
risk actually varies during the operation of the fleet. We use average
risk analysis to assess whether a risk is acceptable when there is
little or no variation in risk from flight to flight. Total fleet risk
is the aggregate sum of all risk throughout a fleet during the
remaining fleet life. Total fleet risk analysis is meaningful in
assessing total societal risk, but it does not assess the variation in
risk between flights or the risk on the worst anticipated flights.
Individual flight risk as used by the FAA is an assessment of the
specific safety risk that exists or will exist on the worst reasonably
anticipated individual flights due to a given issue.
Individual risk analysis is used by the FAA to determine whether
the public's expectation for a reasonable level of safety on each
transport airplane flight is met. An acceptable average risk level and
acceptable total fleet risk do not ensure that all reasonably
anticipated flights (flights with known inoperative equipment, flights
with undetected failures, flights in less-than-ideal but approved and
expected weather or operational conditions, etc.) will provide the
minimum level of safety expected by the public. When the safety risk is
concentrated on flights with a given pre-existing dispatch condition or
expected operational condition, it is possible to have an unacceptable
individual flight safety risk on the worst reasonably anticipated
flights even when the average risk and total fleet risk are acceptable.
In the case of this SNPRM, the risk due to the current Model 757
FQIS design architecture is not spread equally among all of the flights
conducted on the affected airplanes. Instead, the risk is concentrated
almost entirely on the small subset of flights that occur with a latent
failure condition pre-existing in the fuel tank. Flights with such a
latent failure condition and flammable conditions in the center fuel
tank have been judged by the FAA to be reasonably anticipated to occur
based on the numerical probability analysis submitted by the
manufacturer in response to Special Federal Aviation Regulation No. 88
(``SFAR 88,'' Amendment 21-78, and subsequent Amendments 21-82 and 21-
83) (https://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/EEFB3F94451DC06286256C93004F5E07?OpenDocument) and the flammability
analysis submitted to support certification of Boeing's flammability
reduction means (FRM), which Boeing refers to as a nitrogen generation
system (NGS). For those reasonably anticipated flights, the probability
of a catastrophic event (or individual flight safety risk) is the
probability of an additional single failure in the related aircraft
wiring or equipment sending a high energy signal onto the already
compromised in-tank circuit(s). The individual flight safety risk of a
catastrophic event on these flights is in excess of the FAA's threshold
for an unsafe condition determination contained in the published TARAM
Policy Statement PS-ANM-25-05 (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/4E5AE8707164674A862579510061F96B?OpenDocument&Highlight=ps-anm-25-05).
As discussed above, this risk of a catastrophic event on those
flights is due to a single additional failure condition. The risk on
those flights due to a single failure violates the FAA's general fail-
safe design requirements philosophy for transport airplanes. In
general, we issue ADs in cases where reasonably anticipated flights
with pre-existing failures (either due to latent failure conditions or
allowable dispatch configurations) are vulnerable to a catastrophic
event due to an additional foreseeable single failure condition. This
is because the FAA considers operation of flights vulnerable to a
potentially catastrophic single failure condition to be an excessive
safety risk to the passengers on those flights. This SNPRM is
consistent with that continued operational safety philosophy.
In its comment, Boeing stated that the existing design meets the
numerical probability requirements of section 25.1309(b) of the Federal
Aviation Regulations (14 CFR 25.1309(b)), which requires safety
analysis of systems. Boeing concluded that the existing system would
need no further risk reduction to meet the requirements of that rule.
We disagree with this conclusion. First, the existence of a general
safety standard, even if met by a design, does not in and of itself
preclude a determination that there is a specific unsafe condition. The
recognition that compliance with an existing regulation may not be
sufficient to ensure safety is specifically addressed in type
certification by section 21.21(b)(2) of the Federal Aviation
Regulations (14 CFR 21.21.(b)(2)) and
[[Page 9402]]
has often led to changes in regulations to address newly recognized
unsafe conditions. Second, because Boeing mentioned only that rule, we
infer that Boeing may be suggesting that section 25.1309(b) of the
Federal Aviation Regulations (14 CFR 25.1309(b)) is the most relevant
safety analysis standard applicable to the FQIS. As discussed above,
even if later changes to section 25.981 of the Federal Aviation
Regulations (14 CFR 25.981) are not considered and only the original
certification basis for the Model 757 is applied, there are safety
standards more specific to powerplant installations including fuel
tanks and FQIS than section 25.1309(b) of the Federal Aviation
Regulations (14 CFR 25.1309(b)).
The original certification basis for Model 757 airplanes included
section 25.901(c) of the Federal Aviation Regulations (14 CFR
25.901(c)) (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/25.901) at Amendment 25-40. According to
that subsection, ``For each powerplant and auxiliary power unit
installation, it must be shown that no single failure or malfunction or
probable combination of failures will jeopardize the safe operation of
the airplane. . . .'' (The FQIS is considered to be part of the
powerplant installation in accordance with the definition in section
25.901(a) of the Federal Aviation Regulations (14 CFR 25.901(a)).)
Section 25.901(c) of the Federal Aviation Regulations (14 CFR
25.901(c)) sets a more stringent applicable standard than that of
section 25.1309(b) of the Federal Aviation Regulations (14 CFR
25.1309(b)) for catastrophic failure conditions that are due to latent
failure conditions combined with a subsequent single failure condition
(referred to as ``latent-plus-one'' conditions).
The more stringent intent of section 25.901(c) of the Federal
Aviation Regulations (14 CFR 25.901(c)) (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/25.901) is
discussed in further detail in the notice of proposed rulemaking and
the preamble that were published for Amendment 25-102. The FAA's long-
standing practice in applying the ``no single failure or malfunction''
clause of section 25.901(c) of the Federal Aviation Regulations (14 CFR
25.901(c)) has been to apply that standard to all reasonably
anticipated flights--not simply to an average flight or an ideal
flight. As such, we examine all conditions: Flights with reasonably
anticipated pre-existing failure conditions, flights with inoperative
equipment allowed for dispatch, and flights in adverse environmental
conditions or other operational conditions for which the airplane is
approved. If single failure conditions that jeopardize safe operation
of the airplane (catastrophic or hazardous conditions) are identified
as part of this examination, the design is considered to be non-
compliant with section 25.901(c) of the Federal Aviation Regulations
(14 CFR 25.901(c)).
Finally, the SFAR 88 AD-decision policy (Policy Memo ANM-100-2003-
112-15) (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/DC94C3A46396950386256D5E006AED11?OpenDocument&Highlight=anm-100-2003-112-15) classifies a ``latent-plus-one'' condition in a high
flammability fuel tank as an unsafe condition requiring corrective
action. That policy actually provides some relief from the latent-plus-
one criteria contained in the airworthiness regulations.
We have not changed this SNPRM regarding this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): Not Supported by
Risk Analysis
Airlines for America (A4A) proposed that we re-evaluate the NPRM
(77 FR 12506, March 1, 2012) because it is ``not founded on a data-
based risk analysis.'' A4A stated that the FAA determined that an
unsafe condition exists based only on non-compliance with one SFAR 88
criterion. A4A noted that the design approval holder, Boeing, has
performed a numerical probability analysis and has calculated that the
probability of a fuel tank explosion due to the FQIS issue is
approximately one event per billion flight hours, with cargo airplanes
being slightly better due to a lower average tank flammability. A4A
also stated that existing ignition-prevention ADs have reduced the
overall risk of an ignition event to a level that questions the need
for FQIS modification. We infer that the commenter is requesting that
we withdraw the NPRM.
We disagree to withdraw the NPRM (77 FR 12506, March 1, 2012). We
performed a qualitative risk assessment in accordance with our
published SFAR 88 unsafe condition determination policy based on
Boeing's submitted SFAR 88 design review, and determined that the FQIS
design on the Model 757 series airplanes presents an unsafe condition
and that AD action was warranted under that policy. We also performed a
data-based numerical risk analysis using data provided by the
manufacturer, and assessed the risk under the transport airplane unsafe
condition criteria in the TARAM policy currently used by the FAA. Our
risk analysis determined that the risk of an explosion event due to an
FQIS latent-plus-one failure condition is not evenly shared by all
flights of airplanes of the affected design. Instead, the risk of an
FQIS-related fuel tank ignition event is largely concentrated on the
subset of flights that occur with a pre-existing latent failure
condition and that operate with flammable conditions in the center fuel
tank. Based on Boeing's data, such flights are reasonably anticipated
to occur.
For those flights, the risk exceeds the allowable threshold for
individual flight safety risk in the TARAM policy. In addition, that
risk on those flights is due to a single additional failure, which is
inconsistent with the fail-safe design philosophy; that philosophy is
fundamental to the excellent safety record of transport airplanes. (See
FAA Advisory Circular (AC) 25.1309-1A, ``System Design and Analysis,''
dated June 21, 1998 (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2025.1309-1.pdf), for a discussion of the fail-
safe design philosophy.) We would normally classify either of those
conditions as an unsafe condition. Based on this risk analysis, we have
determined that the individual flight safety risk due to this issue on
the worst anticipated flights does not meet the minimum level of safety
required by the FAA and expected by the public. We have not changed
this SNPRM regarding this issue.
Request To Withdraw or Delay NPRM (77 FR 12506, March 1, 2012): Need
Detailed Risk Assessment
FedEx requested that we revise the NPRM (77 FR 12506, March 1,
2012) to provide a numerical risk assessment justifying the proposed
action. UPS made a similar comment. UPS stated that, if the FAA has
gathered new data since the issuance of the ``Reduction of Fuel Tank
Flammability in Transport Category Airplanes'' rule (73 FR 42444, July
21, 2008) (https://www.gpo.gov/fdsys/pkg/FR-2008-07-21/pdf/E8-16084.pdf), referred to as the Fuel Tank Flammability Reduction (FTFR)
rule, the FTFR working group should be reconvened in order to
collaborate and discuss the proposed safety risk, assess the risk
statistically, evaluate solutions and options, and establish accurate
cost and economic impact for the options. FedEx provided an analysis
showing that the total risk of a tank explosion due to this issue on
the fleet of Model 757 cargo airplanes is relatively low. We infer that
the commenters are requesting that we withdraw or delay the NPRM.
[[Page 9403]]
We disagree with the request to withdraw the NPRM (77 FR 12506,
March 1, 2012), pending review of the FAA's numerical risk assessment
by the ``FTFR working group.'' The Aviation Rulemaking Advisory
Committee (ARAC) Fuel Tank Harmonization Working Group (FTHWG) was
tasked to recommend new rulemaking to eliminate or significantly reduce
the risk of exposure to flammable fuel-air mixtures in fuel tanks. The
ARAC FTHWG issued its final report in 1998. The subsequent ARAC Fuel
Tank Inerting Harmonization Working Group (FTIHWG) was tasked to
provide data needed for the FAA to evaluate the feasibility of
implementing regulations that would require eliminating or
significantly reducing the development of flammable vapors in fuel
tanks on transport-category airplanes. This effort was an extension of
the previous work performed by the FTHWG. The ARAC FTIHWG issued its
final report in 2002. The FAA's work in developing the SFAR 88
corrective action decision policy and in determining specific unsafe
conditions was outside the scope and charter of these working groups
that contributed to the FTFR rule (73 FR 42444, July 21, 2008). We
determined that an unsafe condition exists in accordance with the SFAR
88 corrective action decision policy and TARAM policy. We have provided
a summary of our risk assessment as discussed in the responses to
``Request to Withdraw NPRM (77 FR 12506, March 1, 2012): Unjustified by
Risk'' and ``Request to Withdraw NPRM (77 FR 12506, March 1, 2012): Not
Supported by Risk Analysis'' in this SNPRM. As explained previously
(see ``Request to Withdraw NPRM (77 FR 12506, March 1, 2012):
Unjustified by Risk'' in this SNPRM), the FAA determined the unsafe
condition based on the unacceptable risk on anticipated flights with a
latent FQIS failure and flammable fuel tank conditions, not the total
fleet risk. We have not changed this SNPRM regarding this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): No Unsafe
Condition
UPS stated that an SFAR 88 working group analyzed potential fuel
tank ignition sources and that maintenance programs were revised using
MSG3 methodology to meet the revised criteria in ``14 CFR 25.981(3).''
(We assume UPS intended to refer to section 25.981(a)(3) of the Federal
Aviation Regulations (14 CFR 25.981(a)(3))) (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716).) UPS stated that the unsafe
condition identified in the NPRM is inconsistent with the working group
analysis and lacks new data or evidence indicating that ``excessive
flammability or other known unsafe condition exists, or is likely to
develop.'' Finally, UPS made the following observation about the NPRM:
The NPRM fails to consider the beneficial effects of the timing
and effects of the maintenance action in response to a single in-
tank or out-of-tank failure mode, or the beneficial effects of
previous airworthiness directives and other SFAR 88 related actions
taken to mitigate the proposed risk and reduce the probability.
We infer that the commenter is requesting that we withdraw the NPRM
(77 FR 12506, March 1, 2012). We disagree with the request to withdraw
the NPRM. The FAA has performed a risk assessment and has determined
that an unsafe condition does exist, both from a design architectural
standpoint and a numerical risk standpoint. The basis for that
determination is discussed in detail in the responses to ``Request to
Withdraw NPRM (77 FR 12506, March 1, 2012): Unjustified by Risk'' and
``Request to Withdraw NPRM (77 FR 12506, March 1, 2012): Not Supported
by Risk Analysis'' in this SNPRM.
The requirements of section 25.981(a)(3) of the Federal Aviation
Regulations (14 CFR 25.981(a)(3)) cannot be met with an approved
maintenance program only. While an appropriate maintenance program is
required, section 25.981(a)(3) of the Federal Aviation Regulations (14
CFR 25.981(a)(3)) has the effect of setting minimum requirements for
the design architecture and the reliability of system elements. The
Model 757 FQIS as originally designed does not meet all of those
requirements. Previous AD actions, other than the required maintenance
program revisions included in AD 2012-12-15, Amendment 39-17095 (77 FR
42964, July 23, 2012) (which superseded AD 2008-10-11, Amendment 39-
15517 (73 FR 25974, May 8, 2008)), have no effect on the level of
individual flight risk that has been determined to be an unsafe
condition. Some of the airworthiness limitations (AWLs) introduced by
AD 2012-12-15 will reduce the rate of introduction of additional risks
due to future maintenance errors or modifications compromising required
design features, but are not expected to prevent all errors. Those AWLs
do not address problems that may already exist or develop on in-service
airplanes separate from maintenance activity, and they do not address
the basic non-compliant aspects of the original FQIS design
architecture. Those AWLs therefore would not have a significant effect
on either the number of flights that occur with a latent failure
condition or the FQIS-related fuel tank explosion risk level on those
flights estimated in the FAA's risk assessment. We have not changed
this SNPRM regarding this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): No Unsafe
Condition
Airbus acknowledged that the latent-plus-one scenarios that
prompted the unsafe condition determination are a technical
possibility, but stated that the failure combinations that can create
an ignition source are extremely improbable. Airbus also stated that
AD-required airworthiness limitations related to FQIS have
significantly reduced the likelihood of an FQIS-related fuel tank
ignition event. We infer that Airbus is requesting that we withdraw the
NPRM (77 FR 12506, March 1, 2012) based on Airbus's contention that no
unsafe condition exists.
We agree to clarify the likelihood that the unsafe condition could
occur. The FAA's unsafe condition determination was not based on an
assessment of average risk. We agree that the average risk of a fuel
tank explosion on the Model 757 is likely to be lower than the
numerical guidance for ``extremely improbable'' of 1.0x10E-9 per flight
hour. We also agree that the average risk was likely reduced by AD-
required airworthiness limitations that specify extra checks after in-
tank work, and adequate separation of newly installed out-of-tank
wiring from FQIS wiring.
As discussed in ``Request to Withdraw NPRM (77 FR 12506, March 1,
2012): Unjustified by Risk'' in this SNPRM, however, the FAA's unsafe
condition determination was driven by the identification of an
unacceptable level of individual risk that exists on flights that are
anticipated to occur with a pre-existing latent in-tank failure
condition and with a flammable center fuel tank. In the remaining life
of the affected airplanes, a significant number of such flights are
reasonably anticipated to occur--even with the improvements expected
under the AWLs required by AD 2012-12-15, Amendment 39-17095 (77 FR
42964, July 23, 2012). For those flights, a fuel tank explosion can be
caused by an additional single wiring failure. In addition, the
manufacturer's estimated probability of such a failure (the additional
single wiring failure) significantly exceeds the FAA's unsafe condition
numerical threshold for individual flight risk. The probability of
[[Page 9404]]
a fuel tank explosion on those flights is not reduced by the existence
of the above-mentioned AWLs. The AWL that requires extra checks after
in-tank work has been done has the potential to reduce the number of
flights with a pre-existing in-tank failure condition. The AWL that
requires newly installed wiring to meet separation standards should
prevent a significant increase in the risk on those flights that would
have resulted from the installation of additional, inadequately
separated wiring.
We have not changed this SNPRM regarding this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012) Based on Similar
Rulemaking for Cargo Airplanes
ASTAR Air Cargo (ASTAR) requested that we withdraw the NPRM (77 FR
12506, March 1, 2012). In support of its request, ASTAR cited the TWA
Flight 800 accident investigation and its finding that the most
probable cause of the accident was a fuel tank explosion due to a
latent-plus-one failure of the FQIS. ASTAR stated that the FAA had
proposed the FTFR rule (73 FR 42444, July 21, 2008) to mitigate the
risk of fuel tank explosions, and that cargo airplanes had been
exempted from that requirement based on a cost-benefit analysis. ASTAR
argued that, because the basis for exclusion of all cargo aircraft from
the FTFR rule has not changed, all cargo aircraft should be exempt from
any corrective action for the FQIS latent-plus-one issues, and the NPRM
(77 FR 12506, March 1, 2012) should be withdrawn.
We disagree with the request. We have determined that an unsafe
condition requiring corrective action exists in the Model 757 FQIS. The
FTFR rule (73 FR 42444, July 21, 2008) was proposed not because of FQIS
issues specifically, but because of the history of fuel tank explosions
in the transport airplane fleet due to various causes, and an
acknowledgement that industry and the FAA may not be able to anticipate
and prevent all of the fuel tank ignition sources that may arise due to
design and maintenance issues in the life of a fleet of airplanes.
The intent of the FTFR rule (73 FR 42444, July 21, 2008) was to
reduce the overall exposure to flammable fuel tank conditions in the
fleet by approximately one order of magnitude with the expectation that
this would have a significant impact on the rate of fuel tank
explosions in the future due to unanticipated causes. In promulgating
this improvement in the safety standards, the FAA acknowledged that
installation of FRM or ignition mitigation means on a given airplane in
accordance with the FTFR rule would be sufficient to address the FQIS
latent-plus-one unsafe condition. The FTFR rule was not intended to
prevent the FAA from addressing that unsafe condition on airplanes that
would not be affected by the FTFR rule. This was clearly stated in the
preamble to the FTFR rule. We have not changed this SNPRM regarding
this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): Underestimated
Economic Impact
Several commenters requested that we withdraw the NPRM (77 FR
12506, March 1, 2012) because the FAA's cost estimate was too low. A4A
estimated that the costs associated with the NPRM would be up to 3
times the $100,000 to $200,000 estimated by the FAA, and would be
comparable with the cost of Boeing's NGS installation. Goodrich pointed
out that any redesigned FQIS would likely be subject to the current
requirements of section 25.981 of the Federal Aviation Regulations (14
CFR 25.981), resulting in higher costs than estimated by the FAA. A4A
speculated that these higher costs were the reason the NGS was
acknowledged as a method of compliance in the NPRM. A4A and UPS stated
that the FAA appears to be using the NPRM as a method to require the
installation of Boeing's NGS (or equivalent actions) on airplanes that
were not included in the applicability of the FTFR rule (73 FR 42444,
July 21, 2008) based on a cost-benefit analysis.
Although we disagree to withdraw the NPRM, we agree with some of
the commenters' assertions. We agree that our original cost estimate
was low. We agree to adjust the cost estimate, based on the information
provided by the commenters, as discussed below under ``Request to
Revise Cost Estimate Based on New Data.'' Our original estimate was
based on information provided previously by manufacturers of original
equipment FQIS, retrofit FQIS, and both original equipment and
aftermarket transient suppression and isolation devices. Our current
estimate has been increased to reflect the written comments from and
further discussions with Boeing and Goodrich. There is no change to our
determination that an unsafe condition exists. We are therefore
proceeding with this AD action based on the identified corrective
actions that will address the unsafe condition.
We disagree with the characterization that we are using the AD
process to require an FRM to be installed on airplanes that were
excluded from the FTFR rule (73 FR 42444, July 21, 2008) because
inclusion could not be justified in a cost-benefit analysis. The FTFR
rule was intended to enhance the airworthiness standards in a manner
that would increase the level of safety for affected airplanes over
that ensured by the existing regulations. That enhancement was expected
to result from an increased level of protection from ignition sources
that had not been identified by manufacturers in their safety analyses.
That enhancement of the airworthiness standards was required to be
justified by a cost-benefit analysis. Cargo airplanes were excluded
because the FTFR rule safety enhancement could not be justified for
those airplanes from a cost-benefit standpoint.
This SNPRM would not require a safety enhancement over the level of
safety required by previous standards. Instead, this SNPRM addresses an
unsafe condition that was identified from the manufacturer's SFAR 88
safety analysis using the FAA's published corrective action decision
criteria for SFAR 88 identified design issues (see section 25.981(a)(3)
of the Federal Aviation Regulations (14 CFR 25.981(a)(3) (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716). We deferred taking action on
this unsafe condition until after the FTFR rulemaking activity because
the installation of an FRM would sufficiently address the FQIS latent-
plus-one unsafe condition. Now that the FTFR rulemaking process is
complete, we are resuming our activity to address these unsafe
conditions via AD actions. The Boeing NGS has been acknowledged as a
method of compliance in this SNPRM because the Boeing NGS is an
available design that the FAA knows would address the unsafe condition.
No additional change was made to this SNPRM as a result of this
comment.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012) Due to Its Hidden
Effects
A4A requested that we withdraw the NPRM (77 FR 12506, March 1,
2012) because of certain hidden effects that may not have been
anticipated by the FAA. A4A pointed out that some operators are already
anticipating difficulty in meeting the deadlines for compliance with
the FTFR rule (73 FR 42444, July 21, 2008). Based on A4A's assumption
that airlines would comply with the NPRM by incorporating Boeing's
current NGS design, A4A expressed concern that using Boeing's NGS for
these additional airplanes would potentially exceed the rate at
[[Page 9405]]
which industry can modify the fleet affected by the planned ADs and the
FTFR rule. A4A also noted that the compliance time for the NPRM would
overlap the compliance period for the FTFR rule.
While we disagree with the request to withdraw the NPRM, we agree
with some of the assertions made by the commenter. We agree with the
concern that this AD action has the potential to further burden the
operators and modifiers that are working to meet the FRM operating rule
deadlines, because some additional airplanes are likely to be modified
by installing FRM such as Boeing's NGS. But since we issued the NPRM
(77 FR 12506, March 1, 2012), two factors have changed that reduce
A4A's concern. First, we have identified a less costly option for cargo
airplanes, which most cargo operators are expected to prefer over
installation of FRM. This is expected to result in significantly fewer
airplanes competing for FRM modification resources. Second, this AD
action has been delayed due to numerous factors, including the number
of comments, the development of a different corrective action option,
and the resultant need to extend the comment period to allow the public
the chance to comment on these proposed changes.
Also, as discussed below under ``Request to Extend Compliance Time
Pending Issuance of Service Information,'' we have extended the
proposed compliance time by 12 months. These delays and changes will
result in the AD compliance deadline being at least 3 years beyond the
final compliance deadline of the FTFR rule (73 FR 42444, July 21,
2008). Similar planned ADs for other models have been similarly
delayed. We have determined that the industry modification capacity
will be sufficient to support the modification of the expected
additional airplanes receiving FRM within the new proposed compliance
time. We have not changed this SNPRM further regarding this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): Potential
Significant Rule
A4A stated that the combined costs of the NPRM (77 FR 12506, March
1, 2012) and other anticipated ADs for U.S. airplane models with an
FQIS latent-plus-one issue would exceed $177 million and would require
a cost-benefit analysis. We infer that the commenter is requesting we
withdraw the NPRM (77 FR 12506, March 1, 2012) on the basis that the
planned ADs for various models, if combined, would qualify as a
significant rule that would require a cost-benefit analysis.
We disagree with the request. First, in assessing whether an AD is
a significant rule in accordance with FAA policy, we do not combine the
cost of multiple planned ADs for different airplanes, even when the
design issues and unsafe conditions addressed are similar. Second, the
changes discussed previously in this SNPRM will significantly reduce
the cost impact. We have made no further changes to this SNPRM
regarding this issue.
Request To Withdraw NPRM (77 FR 12506, March 1, 2012): Inadequate
Notice to Public
A4A recommended that we provide information on any other designs
that have been reviewed under SFAR 88, and provide industry with
information regarding their planned disposition. A4A asserted that,
during the FTFR rulemaking activity, we did not provide notice to the
industry that we still intended to address the FQIS issues identified
via SFAR 88. We infer that A4A is requesting that we withdraw the NPRM
(77 FR 12506, March 1, 2012) based on inadequate notice to the public
and the chance to comment on the proposal. The commenter stated that
the preamble of the FTFR rule (73 FR 42444, July 21, 2008) was unclear
regarding whether AD actions would be taken to address the FQIS issues
on airplanes that were not required to incorporate FRM.
We disagree with the request to withdraw the NPRM (77 FR 12506,
March 1, 2012). We determined that an unsafe condition exists. FTFR
rulemaking was done because the FAA recognized the benefit for the
specific design changes involving incorporation of FRM required by the
FTFR rule (73 FR 42444, July 21, 2008) to enhance fuel tank safety.
Because the FTFR final rule requires action on only a subset of the
airplanes that have the FQIS unsafe condition, we are taking action to
address the remaining airplanes that will continue to have the unsafe
condition if no further corrective action is taken.
The commenter has taken the statement from the FTFR preamble out of
context. In fact, the paragraph from which the commenter quoted
specifically states that the FAA expected to take AD action to address
FQIS issues identified through SFAR 88 analyses. The paragraph simply
states that the proposed FRM has the potential to reduce the industry
cost associated with those expected ADs because the installation of an
FRM likely would eliminate the need for action to further address the
FQIS issue with AD actions. The purpose of that statement was to note
that there would be some cost savings to industry resulting from the
elimination of other actions required to address an unsafe condition
for the airplanes affected by the proposed rules, and to point out that
the FAA did not take credit for those potential cost reductions in
assessing the cost of the FTFR rule (73 FR 42444, July 21, 2008)
because the costs were not well understood at the time. That statement
was not a commitment by the FAA to reverse its intentions to address an
identified unsafe condition on the airplanes that are not required to
incorporate FRM. We have not changed this SNPRM regarding this issue.
Request for Cost-Benefit Analysis
Boeing, FedEx, Airbus, ASTAR Air Cargo, and A4A requested that we
perform a cost-benefit analysis for the NPRM (77 FR 12506, March 1,
2012) and publish the results. Airbus stated that its own cost
estimates exceed those used by the FAA for the FTFR rule (73 FR 42444,
July 21, 2008) cost-benefit analysis that ended up excluding cargo
airplanes. A4A and ASTAR Air Cargo requested that the NPRM be withdrawn
until a cost-benefit analysis is performed. The commenters suggested
that a cost-benefit analysis would show that the NPRM cannot be
justified because the costs of the proposed actions would exceed the
monetary value of the AD's safety benefits. The commenters cited the
cost-benefit analysis that was performed to justify the FTFR rule, and
pointed out that a requirement for FRM could not be justified for the
airplanes that would be affected by the proposed AD.
We infer that, pending a full cost-benefit analysis, these
commenters are requesting that we either withdraw the NPRM or delay
this action further until a cost-benefit analysis demonstrates that an
AD is justified in this case. We disagree. The FAA's process and legal
obligations for introducing new airworthiness standards are different
from those for initiating an AD to address an unsafe condition in an
existing product. In addition, the commenters' assertions were based on
the assumption that the only design solution that would be made
available to address the solution would be an FRM, or another solution
of similarly high cost.
When we propose a new airworthiness standard, as in the case of the
FTFR rule (73 FR 42444, July 21, 2008), we are required to perform a
cost-versus-benefit comparison to justify the application of the new
standard. The
[[Page 9406]]
decision in that rulemaking action--to not require FRM installation on
cargo airplanes--was based in significant part on cost estimates that
industry provided to show that AD-required FQIS design changes would be
far less costly than installing FRM on cargo airplanes. We specifically
considered the option to not require retrofit of cargo airplanes with
FRM because of the expectation that alternative design solutions to
address the specific, known unsafe condition of FQIS latent-plus-one
vulnerability would still be required through AD actions. For this AD
action, however, industry submitted written comments and made verbal
statements that the cost of an FQIS design solution would be comparable
to, and possibly greater than, the cost of its FRM modification.
In general, a full cost-benefit analysis is rarely required for an
AD. As a matter of regulation, in order to be airworthy, an aircraft
must conform to its type design and be in a condition for safe
operation. The type design is approved only after the FAA makes a
determination that the design complies with all applicable
airworthiness requirements. In adopting and maintaining those
requirements, the FAA has already made the determination that those
requirements establish a level of safety that is cost beneficial. A
finding of an unsafe condition that warrants AD action means that this
cost-beneficial level of safety is no longer being achieved, and the
required AD actions are necessary to restore that level of safety.
Because this level of safety has already been determined to be cost
beneficial and does not add an additional regulatory requirement, a
full cost-benefit analysis for each AD would be redundant and
unnecessary.
We have not changed this SNPRM regarding this issue.
Request To Revise Applicability Statement To Clarify the Intent of the
Rule for Non-U.S.-Registered Airplanes
The European Aviation Safety Agency (EASA), the Technical Agent for
the Member States of the European Community, requested that we revise
the proposed applicability. Specifically, EASA requested that we add
Model 757 airplanes that did not have FRM installed in production. EASA
further requested that we exclude airplanes equipped with FRM that meet
the FAA's FTFR rule (73 FR 42444, July 21, 2008). EASA stated that it
has not issued an operating regulation corresponding to the FAA's
requirements for retrofitting FRM in the FTFR rule. EASA noted that, at
least for European operators, the unsafe condition would not be
required to be addressed for airplanes that would have been subject to
the FTFR rule in the U.S., and suggested that EASA might have to issue
an AD (instead of adopting the FAA AD), with similar technical content,
but extending the applicability to the entire Model 757 fleet in
Europe.
We agree to revise the applicability. EASA is correct that the
unsafe condition potentially affects all Model 757 airplanes, whereas
the applicability statement in the NPRM (77 FR 12506, March 1, 2012)
could be interpreted as not covering airplanes in passenger service
that are not operated under parts 121, 125, or 129 of the Federal
Aviation Regulations (14 CFR part 121, 125, or 129). The EASA comment
makes it apparent that the proposed applicability statement may be
unclear to some operators and regulatory authorities. While the
applicability statement in the NPRM is technically correct (e.g., an
EASA operator is not operating under those FAA operating rules and
therefore would have been subject to the AD), we now agree that there
is a potential for confusion that can be eliminated by more directly
stating the requirement and applicability in a manner similar to that
proposed by EASA in their comment. We have changed the applicability in
this SNPRM to all Model 757 airplanes except for airplanes equipped
with an FRM approved by the FAA as compliant with the FTFR requirements
of section 26.33(c)(1) of the Federal Aviation Regulations (14 CFR
26.33(c)(1)), as discussed below. As with any required equipment, the
FRM must be operational with the exception of any relief granted under
master minimum equipment list (MMEL) provisions.
With the clarification in paragraph (c), ``Applicability,'' of this
SNPRM, we have determined that paragraph (h), ``Optional Installation
of Flammability Reduction Means,'' of the NPRM would be superfluous and
is no longer necessary. Paragraph (c) of this supplemental NPRM, as
revised, would not apply to airplanes equipped with FRM.
Requests To Withdraw NPRM (77 FR 12506, March 1, 2012) Based on
Applicability
Boeing and ASTAR Air Cargo requested that we withraw the NPRM (77
FR 12506, March 1, 2012) because cargo airplanes on average have a
lower flammability exposure due to a larger portion of night operations
(with resultant cooler outside air temperatures) and a lower rate of
utilization of the cabin air conditioning system on the ground. Boeing
stated that operation of the air conditioning system on the ground
significantly contributes to the heating of the center fuel tank.
Boeing's analysis estimated a fleet average flammability for the center
fuel tanks of the cargo airplane fleet of 50 percent of the level for
the passenger fleet. Boeing also noted that cargo airplanes generally
accumulate flight hours at a lower rate than passenger airplanes.
We disagree with the request to withdraw the NPRM (77 FR 12506,
March 1, 2012).
We acknowledge that the increased night operation and reduced use
of the air conditioning system on the ground reduce the average
flammability exposure for the fleet of cargo airplanes relative to the
fleet of passenger airplanes. That reduction in fleet average
flammability, however, is not sufficient to allow the center fuel tanks
on those airplanes to be classified as low flammability fuel tanks. The
FAA's determination that an unsafe condition exists for the cargo
airplanes as well as passenger airplanes was driven by the FAA's
individual risk safety decision criteria rather than an average risk or
fleet risk criterion. There is no difference in the individual flight
risk on the worst anticipated flights between passenger airplanes and
cargo airplanes due to this issue. The worst anticipated flights in
either case involve a pre-existing latent in-tank failure and operation
with flammable conditions in the center fuel tank. Flights with that
combination of conditions are anticipated to occur in both the
passenger fleets and cargo fleets (although at a somewhat lower
relative rate on cargo airplanes, for the reasons cited by the
commenters).
For those flights, a fuel tank explosion could occur due to a
single failure in the airplane wiring or the FQIS processor that
conducts a high level of electrical energy onto circuits that enter the
fuel tank. As discussed previously in the response to ``Request to
Withdraw NPRM (77 FR 12506, March 1, 2012): Unjustified by Risk,'' this
is not consistent with the FAA's fail-safe design philosophy for
transport airplanes. In addition, the numerical probability of the
single failure as estimated by the manufacturer and the FAA
significantly exceeds the unsafe condition threshold for individual
flight risk in the FAA's TARAM) Policy Statement PS-ANM-25-05 (https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/4E5AE8707164674A862579510061F96B?OpenDocument&Highlight=ps-anm-25-05).
We have therefore determined that an unsafe condition does exist on
cargo
[[Page 9407]]
airplanes even in consideration of the lower fleet exposure factors
cited by the commenters.
While we have determined that this unsafe condition requires
corrective action, we have identified additional corrective action
options that we expect will be significantly less costly to incorporate
than the originally proposed requirement. We have determined that this
additional corrective action option is not suitable for passenger
airplanes because it does not provide a sufficient level of risk
reduction for passenger operations. The FAA normally does not
differentiate between the safety requirements or corrective action
requirements for cargo airplanes and passenger airplanes. However,
after reviewing all of the comments on the estimated high cost of the
corrective action and the uncertainty in those estimates, we examined
other options for less costly risk reduction on cargo airplanes. We
identified an option that provides significant risk reduction at a per-
airplane cost that is estimated to be less than one-quarter of the cost
of the original proposal (77 FR 12506, March 1, 2012). The amount of
risk reduction from this option is not at this time considered to be
adequate to address the unsafe condition for passenger airplanes.
In this case, the FAA is proposing to accept a higher level of
individual flight risk exposure for cargo flights that are not fail-
safe due to the absence of passengers and the resulting significant
reduction in occupant exposure on a cargo airplane versus a passenger
airplane, and due to relatively low estimated individual flight risk
that would exist on a cargo airplane after the corrective actions are
taken. The FAA has allowed a higher risk level to exist on cargo
airplanes due to other issues, and applies a slightly less stringent
numerical fleet risk threshold standard for unsafe conditions in the
published TARAM policy. Because this is an unusual determination, we
have reopened the comment period to give affected operators, pilots,
and the public the opportunity to comment on this proposal.
We expect that the optional wire separation design change to
support compliance with the proposed AD for cargo airplanes will
involve the manufacturer or any other modifier petitioning for a
partial exemption from the ``latent-plus-one'' requirements of sections
25.901(c) and 25.981(a)(3) of the Federal Aviation Regulations (14 CFR
25.901(c) and 14 CFR 25.981(a)(3)). We have informed the manufacturer
that we are open to granting such an exemption, and they indicated
their willingness to make such a petition.
We have added new paragraph (h) in this SNPRM to allow repetitive
FQIS built-in test equipment (BITE) checks and modification of the
airplane by separating FQIS wiring from other aircraft wiring that is
not intrinsically safe (in a manner acceptable to the FAA) as an
additional option for airplanes used exclusively for cargo operations.
We have redesignated subsequent paragraphs of this SNPRM accordingly.
Request To Change Applicability To Address Unsafe Condition on
Airplanes With FRM
National Air Traffic Controllers Association (NATCA) requested that
we revise the NPRM (77 FR 12506, March 1, 2012) to include airplanes on
which FRMs were incorporated either voluntarily or to comply with the
FTFR rule (73 FR 42444, July 21, 2008). NATCA noted that the
introduction of FRM on such airplanes only reduces the fraction of time
the airplane is operated with flammable conditions in its fuel tanks,
but does not eliminate flammable operation. NATCA further noted that
FAA operating rules allow limited operation of the airplane with the
FRM inoperative. NATCA added that the likelihood of a fuel tank
explosion during operation with flammable tanks is similar regardless
of whether an FRM is installed.
We disagree with the request. We have developed and published
policy for determination of unsafe conditions and the need for
corrective actions during the evaluation of SFAR 88 fuel tank safety
review findings. The decision to allow FRM as an acceptable mitigating
action for the identified unsafe condition is consistent with that
policy. We acknowledge NATCA's point that, if no actions are taken on
an airplane to correct the FQIS latent-plus-one issue other than
installation of an FRM, flights on that airplane where FRM is
inoperative or ineffective would have the same risk of a fuel tank
explosion due to the FQIS latent-plus-one issue as flights on an
airplane with no FRM installed. However, the published unsafe condition
criteria (section 25.981(a)(3) of the Federal Aviation Regulations (14
CFR 25.981(a)(3)) (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716)
differentiate between low- and high-flammability fuel tanks, with a
higher level of conservatism applied to high-flammability tanks.
The criteria recognize that low-flammability tanks are still
flammable for a portion of their operating time, and the criteria
include ignition prevention thresholds commensurate with that level of
flammability. The regulatory performance standard for FRMs is
equivalent to the flammability of a conventional aluminum wing tank,
which is the benchmark for the definition of a low-flammability tank.
We have therefore determined that it is appropriate to treat ignition
sources in center fuel tanks with compliant FRMs the same way they
would be treated for a tank that has inherent low flammability. Because
the FQIS latent-plus-one vulnerability for Model 757 airplanes was
classified as a theoretical vulnerability and not as a condition known
to have occurred, the SFAR 88 corrective action policy does not require
corrective action for that condition in low-flammability fuel tanks.
The installation of an FRM causes the center fuel tank to meet the
criteria for classification as a low-flammablity fuel tank, and
therefore FRM installation was considered to be acceptable mitigating
action. We have not changed this SNPRM regarding this issue.
Request To Remove Requirement for Goodrich FQIS
Goodrich stated that its FQIS fuel height and dielectric sensor
interface circuitry presently meets the energy, voltage, and current
limits specified in FAA AC 25.981-1C, ``Fuel Tank Ignition Source
Prevention Guidelines,'' dated September 19, 2008 (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716). Goodrich stated that the system
design would require multiple serial failures to enable a fault to
propagate to the tank, resulting in the combination of those failures
being extremely improbable on average. Goodrich added that the system
built-in test detects open circuits and short circuits in the sensors
and aircraft wiring, including shorts to structure. Goodrich stated
that there have been no failures in service in which the Goodrich FQIS
exposed the fuel tank to an unsafe condition. Goodrich asked whether
the actual system operation and service life have been considered in
the evaluation of the probability of an unsafe condition and the
mitigation provided by the present Goodrich FQIS.
We infer that the commenter is requesting that we revise the NPRM
(77 FR 12506, March 1, 2012) to eliminate any requirement for
corrective action for airplanes equipped with a Goodrich FQIS. We
partially agree. The Goodrich system is recognized as having
significant improvements relative to the
[[Page 9408]]
original 757 system developed by another manufacturer. We recognize
that the Goodrich FQIS has the ability to identify a significant
portion of the potential latent in-tank failure conditions that can
occur inside the fuel tanks. Those conditions, however, are detected
and corrected only when the built-in test capability is activated
during maintenance. Currently, activating the built-in test features is
required only when troubleshooting an FQIS problem that has become
apparent to flight or maintenance crew. This still potentially leaves
significant latency periods for those failures.
We have agreed that the Goodrich processor has sufficient circuit
isolation such that the processor itself is not expected to create hot
short conditions in tank circuits, and is not expected to pass energy
from non-tank-side low-voltage hot shorts onto tank-side circuits.
There remains, however, a significant potential for a single failure
causing a hot short onto tank-side circuits, or a single failure
causing a high-voltage hot short onto non-tank-side circuits to cause
non-intrinsically safe energy, voltage, or current levels to be
conducted into the fuel tanks. The latent-plus-one concern therefore
still exists even with the additional detection capabilities that exist
in the Goodrich FQIS. We have determined this concern requires
corrective action in accordance with the SFAR 88 corrective action
decision policy discussed previously. We disagree with the request to
revise this SNPRM to eliminate any requirement for corrective action
for airplanes equipped with a Goodrich FQIS because we have determined
that an unsafe condition requiring corrective action exists on the
Goodrich FQIS-equipped airplanes even after considering the differences
between the Goodrich FQIS and the original 757 system developed by
another manufacturer. We have not changed this SNPRM regarding this
issue.
Request To Clarify Affected Tanks
FedEx requested that we revise the NPRM (77 FR 12506, March 1,
2012) to clarify that only the center fuel tank is affected. FedEx
stated that the proposed wording could be interpreted as applying to
all tanks.
We agree to clarify the intent of this SNPRM. The FQIS wiring and
related system components are to be modified to the extent necessary to
prevent the development of an ignition source in the center fuel tank
due to FQIS failure conditions. If modification of wing tank-related
components is necessary to prevent an ignition source in the center
fuel tank (for example, because of common wiring between the tanks),
then that modification would be required. Paragraph (g) of this SNPRM
already states this (``modify the FQIS wiring or fuel tank systems to
prevent development of an ignition source inside the center fuel
tank''). A change to this SNPRM itself therefore is not necessary.
Request To Revise Proposed AD Requirements To Apply to All Fuel Tanks
NATCA noted that action similar to the proposed requirements of the
NPRM (77 FR 12506, March 1, 2012) was required for all fuel tanks on
early Model 747 and 737 airplanes via AD 98-20-40, Amendment 39-10808
(63 FR 52147, September 30, 1998); and AD 99-03-04, Amendment 39-11018
(64 FR 4959, February 2, 1999). The commenter also noted that the FAA's
published SFAR 88 unsafe condition criteria (section 25.981(a)(3) of
the Federal Aviation Regulations (14 CFR 25.981(a)(3)) (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716)) require corrective action for
``known latent-plus-one conditions'' in both low- and high-flammability
tanks.
We infer the commenter is requesting that we revise the proposed
actions of the NPRM (77 FR 12506, March 1, 2012) to apply to all fuel
tanks. We disagree. NATCA's interpretation of the word ``known''
appears to be different from that intended by the FAA when the SFAR 88
decision criteria were developed and implemented. For low-flammability
fuel tanks, the FAA has proposed that corrective action for ``latent-
plus-one'' issues be required only in cases where the particular
latent-plus-one scenario is known to have occurred on that particular
design. Where relevant design details are significantly different, a
condition that has occurred with one design is not considered to be a
``known'' latent-plus-one condition on another design simply because
the same architectural vulnerability theoretically exists.
In the case of AD 98-20-40, Amendment 39-10808 (63 FR 52147,
September 30, 1998); and AD 99-03-04, Amendment 39-11018 (64 FR 4959,
February 2, 1999); we required corrective action for all fuel tanks
because the details of those designs were identical or very similar to
the details of the design that were considered to be the most likely
cause of the 1996 Model 747-100 accident. The actions of AD 98-20-40
and AD 99-03-04 are consistent with the intent of the later-developed
SFAR 88 unsafe condition criteria. We have not changed this SNPRM
regarding this issue.
Request for Specific Corrective Action
EASA noted that the NPRM (77 FR 12506, March 1, 2012) did not cite
service information for a specific design solution other than
acknowledging FRM as an acceptable method of compliance. We infer that
EASA is requesting that the NPRM propose to require a specific
corrective action for the unsafe condition. EASA pointed out that,
under its regulations and policies, EASA issues ADs based on specific
solutions provided by the responsible manufacturer. EASA stated that,
in the absence of a specific solution, EASA will not be in a position
to simply adopt the FAA AD, and may need to develop its own AD or find
another solution.
We disagree with the request to require a specific corrective
action in this SNPRM. In this case, the manufacturer has not provided a
corrective action specific to FQIS in time to support the NPRM, noting
that they have provided service instructions to install FRM that the
FAA has defined as one method of compliance within the NPRM (77 FR
12506, March 1, 2012). While the FAA has the authority to compel the
manufacturer to provide a solution specifically providing FQIS
protection, in this case the FAA decided to seek public comment on the
NPRM (77 FR 12506, March 1, 2012) before deciding whether to take that
action. The FAA already requires the vast majority of passenger
airplanes registered in the U.S. to be equipped with FRM, and since we
defined incorporation of FRM as one method of compliance within the
NPRM (77 FR 12506, March 1, 2012), and because Boeing and Goodrich
provided information to show that a specific FQIS protection solution
would have a per-airplane cost similar to that of Boeing's FRM design
solution, we have determined there is no practical reason to require
the manufacturer to provide a corrective action specific to FQIS for
passenger airplanes. Consideration of the many comments on the NPRM (77
FR 12506, March 1, 2012) has resulted in a revision of the FAA's
approach for cargo airplanes, leading to a significantly different
proposed AD. At this point we do expect the manufacturer to provide
service information for the proposed optional solution for cargo
airplanes. We have, however, decided not to further delay action on
this issue by waiting for that service information. The service
information is expected to be released shortly after the issuance of a
final rule.
[[Page 9409]]
No change to this SNPRM is necessary for this issue. If service
information becomes available before the final rule is issued, we might
consider incorporating it into the AD.
Request for Information on Modifications
Icelandair requested more detailed information on the specific
modifications that would need to be performed to comply with the
proposed requirements specified in the NPRM (77 FR 12506, March 1,
2012), and asked if a related service bulletin was available.
Service information is available for incorporation of FRM approved
by the FAA as compliant with the FTFR rule (73 FR 42444, July 21, 2008)
requirements of section 26.33(c)(1) of the Federal Aviation Regulations
(14 CFR 26.33(c)(1)).
As stated previously, we have revised the NPRM (77 FR 12506, March
1, 2012) to provide more specific information about a less costly
optional modification for cargo airplanes. Service information related
to this modification is not currently available. We have not changed
this SNPRM further regarding this issue.
Request for Optional Modification
Goodrich requested that we revise the NPRM (77 FR 12506, March 1,
2012) to require or allow a modification to separate and shield the
FQIS tank-side circuits from other wiring as corrective action for the
identified unsafe condition. Goodrich referred to its discussion
regarding the capability of the Goodrich FQIS processor to isolate the
tank-side circuits from the non-tank-side circuits.
We partially agree with the request. We considered that method of
compliance and determined that the benefit from that corrective action
would be sufficient for cargo airplanes when combined with regular FQIS
checks using the previously mentioned built-in test capability. We
disagree with allowing the proposed alternative for passenger airplanes
that are not equipped with FRM because the level of risk reduction
achieved from that alternative corrective action would not provide a
sufficient risk reduction for those airplanes. Even when the built-in
test capability is periodically exercised, there will still be a
significant latency period for some in-tank failures. The risk on the
flights where those failures exist and where flammable conditions exist
in the fuel tank is considered to be excessive for passenger airplanes,
because it results from a single additional failure (those flights
would not be fail-safe). Even if it did not result from an additional
single failure, it would still exceed the TARAM-allowable risk level
for individual flight risk. This determination is consistent with the
SFAR 88 corrective action decision policy and TARAM policy. As
discussed previously, we have added new paragraph (h) in this SNPRM to
allow the option of a periodic BITE check and partial wire separation
for cargo airplanes.
Request for Repetitive Inspections or Replacement
Oy Air Finland Ltd. stated that wires within the fuel tank must
remain in an undamaged condition and therefore requested that we revise
the NPRM (77 FR 12506, March 1, 2012) to specify their repetitive
inspection or replacement. The commenter provided no justification.
We disagree with including specific requirements to periodically
inspect or replace the wiring within the fuel tanks because
airworthiness limitations and existing maintenance practices are
already in place to monitor the condition of in-tank wiring. This SNPRM
would require installation of flammability reduction means or a
combination of periodic system checks (which would detect many types of
wiring defects or damage) and wire separation improvements, either of
which would significantly reduce the probability of a fuel tank
explosion on a given airplane flight to an acceptable level. We have
not changed this SNPRM regarding this issue.
Request To Compel Issuance of Service Information
NATCA requested that we enforce sections 21.99 and 183.63(d) of the
Federal Aviation Regulations (14 CFR 21.99 and 183.63(d)) and SFAR 88,
Amendment 21-78, and subsequent Amendments 21-82 and 21-83) (https://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/EEFB3F94451DC06286256C93004F5E07?OpenDocument) to obtain necessary
service information from design approval holders. NATCA noted that EASA
cannot ``issue ADs'' (that is, EASA may not be able to adopt the FAA AD
per se) if specific service information is not identified. NATCA
expressed concern that other civil aviation authorities may take a
similar position.
We partially agree with the request. We agree that the cited
regulations are relevant in setting requirements for action by design
approval holders when we have identified an unsafe condition. We also
recognize that issuance of an AD without service information creates
significant issues for regulatory agencies and for operators that must
comply with the AD. This SNPRM, however, is not the appropriate forum
to discuss potential enforcement action. We have not changed this SNPRM
regarding this issue.
Boeing's Planned Service Information
Boeing stated that it will offer only the Boeing FRM as a solution,
if the AD is issued as proposed. Boeing added that it does not develop
detailed cost estimates for design changes they do not intend to
provide. Further, Boeing stated that it does not advocate FRM
installation on airplanes for which FRM is not required under the FTFR
rule (``Reduction of Fuel Tank Flammability in Transport Category
Airplanes'' (73 FR 42444, July 21, 2008)). Boeing proposed no change to
the NPRM (77 FR 12506, March 1, 2012). Boeing noted that a requirement
to install an FRM on the affected airplanes could not be justified in
the cost-versus-benefit analysis performed for the new FTFR rule, and
therefore cannot be justified to address the unsafe condition
identified by the FAA.
We have provided the basis for this SNPRM in response to ``Request
for Cost-Benefit Analysis'' in this SNPRM. We emphasize, however, that
this SNPRM does not require installation of a nitrogen generation
system or other FRM. The actions specified in this SNPRM will correct a
specific, known unsafe condition with the FQIS. We decided to propose
this AD action without specific service information for the expected
design solution specifically because Boeing has not to date provided a
design solution specific to FQIS. As a result of considering the
comments to the NPRM (77 FR 12506, March 1, 2012), the FAA has
identified a less costly option for Model 757 cargo airplanes. We have
asked Boeing to develop service information for that option, and Boeing
has agreed. Since the FAA already requires the vast majority of
passenger airplanes registered in the U.S. to be equipped with FRM and
we defined incorporation of FRM as one method of compliance within the
NPRM (77 FR 12506, March 1, 2012), and because Boeing and Goodrich
provided information to show that a specific FQIS protection solution
would have a per-airplane cost similar to that of Boeing's FRM design
solution, we have determined there is no practical reason to require
the manufacturer to provide a corrective action specific to FQIS for
passenger airplanes. We have not further changed this SNPRM regarding
this issue.
[[Page 9410]]
Request To Extend Compliance Time Pending Issuance of Service
Information
A4A requested that we revise the NPRM (77 FR 12506, March 1, 2012)
to extend the compliance time from 60 months to ``a 96-month compliance
period that commences one year after the effective date of the AD''--
for a total compliance time of 9 years. A4A noted that SFAR 88 (Special
Federal Aviation Regulation No. 88 (``SFAR 88,'' Amendment 21-78, and
subsequent Amendments 21-82 and 21-83) (https://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/EEFB3F94451DC06286256C93004F5E07?OpenDocument)) required design
solutions for non-compliant designs to be provided by December 6, 2002,
and considered that the absence of service information reflects a
failure of communication and coordination, presumably between the FAA
and Boeing. A4A was concerned that Boeing's declaration that it does
not intend to develop a design solution other than its existing
nitrogen generation system indicates that the development of any other
design solution would be technically challenging and time consuming.
A4A also cited the implementation of the requirements of part 26 of the
Federal Aviation Regulations (14 CFR part 26) as an example of the FAA
underestimating the costs and time required to develop design
solutions.
We partially agree with the request to extend the compliance time.
While we agree to provide additional time for manufacturers to develop
service information, we acknowledge that service information is not
likely to be available until several months after the final rule is
issued. We disagree with the assertion that the delay in proposing an
AD to address the FQIS latent-plus-one unsafe conditions on several
transport airplane models reflects a failure to communicate and
coordinate with design approval holders.
In 2003, the FAA held a series of AD board meetings to decide which
of the design areas identified in SFAR 88 design reviews as non-
compliant on Boeing airplanes would be classified as unsafe conditions
requiring AD action. The FQIS latent-plus-one issue was identified as
an unsafe condition for high flammability fuel tanks at that time for
several models, including the Model 757. Several airplane models from
other manufacturers were identified as having similar issues. However,
during that same time period, the National Transportation Safety Board
(NTSB) had recommended FAA action to require inerting systems for
center fuel tanks, and the FAA was working with industry to develop a
practical nitrogen generation system for new production and retrofit
installations on transport airplanes. The FAA was also planning to
propose a new rule requiring those systems to be installed on new and
existing airplanes, as recommended by the NTSB. The FAA recognized
that, if such a system was installed on a given set of airplanes, the
unsafe condition determination for the center fuel tank latent-plus-one
would be addressed due to the modified center fuel tank meeting the
conditions for a low flammability fuel tank after installation of a
nitrogen generation system.
The FAA therefore decided to defer addressing the FQIS latent-plus-
one issue on the affected airplanes until after the outcome of the FTFR
rulemaking process. Now that the rulemaking process is complete and the
safety enhancement provided by the FTFR rule (73 FR 42444, July 21,
2008) has been limited to certain airplanes (14 CFR part 121, 125, and
129 passenger airplanes), the FAA is addressing the FQIS latent-plus-
one unsafe conditions on the airplanes that are not required to receive
the safety enhancement of the FTFR rule. This history was discussed in
detail in the NPRM (77 FR 12506, March 1, 2012) and in the preamble for
the FTFR rule.
We disagree with extending the compliance time to 9 years. Service
information to support the modification portion of the option for cargo
airplanes is expected to be available shortly after the final rule is
issued. The service information for the inspection portion of that
option and the FRM option is already released. We have determined that
a compliance time extension to 72 months for the modification will give
adequate time for manufacturers to complete the remaining service
information and for operators to complete the modification.
We have revised the compliance time in this SNPRM to 72 months
after the effective date of the AD.
Request To Reduce Compliance Time
NATCA requested that we reduce the compliance time from 60 months
to 36 months because of the time that has already passed to address
this unsafe condition since its identification in 2003.
While we acknowledge the time that has passed since the
identification of the unsafe condition identified in this SNPRM, the
FAA delayed taking action for this issue while we developed the FTFR
rule (73 FR 42444, July 21, 2008), determined its applicability, which
directly affected the applicability of this SNPRM, and implemented the
FTFR rule. Now that we are proposing action for the affected airplanes,
we must consider the ability of industry to develop an appropriate
design change and incorporate it on all affected airplanes; we find
that it is not practical for industry to respond to this AD in only 3
years. We have therefore not reduced the compliance time in this SNPRM.
Request To Revise Cost Estimate Based on New Data
Boeing requested that we revise the cost estimate specified in the
NPRM (77 FR 12506, March 1, 2012) because the actual cost to develop
and implement a design change to fully address the FQIS latent-plus-one
failure conditions would be significantly higher. Boeing estimated in
their comment that the cost to develop and implement a transient
suppression unit design for Model 757 airplanes would be about the same
as the cost of Boeing's FRM provided for the airplanes affected by the
FTFR rule (73 FR 42444, July 21, 2008): in excess of $300,000 per
airplane for airplanes equipped with the early FQIS design, and in
excess of $200,000 per airplane for airplanes equipped with a Goodrich
FQIS.
In a subsequent meeting initiated by the FAA to obtain more detail
on this cost estimate, Boeing provided a higher cost estimate than they
provided in their written comment. However, in subsequent discussions
with Boeing as part of developing this SNPRM, Boeing indicated that
they were working on an isolation-based design alternative to the FAA's
proposed modification option for the cargo airplanes that would likely
be significantly less costly than the FAA's proposed cargo airplane
option of partial wire separation.
We partially agree with the commenter. We agree to revise the cost
estimate because both Boeing and one of Boeing's affected FQIS vendors
provided similar cost estimates that were higher than the estimates
made in the NPRM (77 FR 12506, March 1, 2012) by the FAA. We disagree
to revise the cost estimate as Boeing proposed. We have received
several inconsistent cost estimates from industry during the
development of the FTFR rule (73 FR 42444, July 21, 2008), in their
written comments to the NPRM, and during discussions of the FAA's
proposed alternative for cargo airplanes. We have therefore provided a
revised cost estimate for the originally proposed action based on input
from Boeing's written comment and from the FQIS vendor. We also have
considered that it
[[Page 9411]]
is likely that aftermarket vendors may develop competing design
solutions, as has occurred for other similar ADs, and those solutions
will likely cost less than the original manufacturer's solutions.
In addition, we have identified an additional compliance option--
with a different cost--for cargo airplanes. That cost estimate is based
on Model 757 service information that described a very similar
modification. We have used the work-hour estimate from that service
bulletin, increased the work-hour estimate by 20 percent to account for
any unforeseen increases in the work, and increased the parts prices to
account for inflation and the potential that additional parts may be
needed.
Request To Revise Cost Estimate Based on AD Scope
Goodrich requested that, if the intent of the NPRM (77 FR 12506,
March 1, 2012) is to protect all fuel tanks rather than just the center
fuel tank, we revise the cost estimate of the NPRM accordingly.
Goodrich stated that the cost estimate is based on three assumptions:
(1) That current technology circuit isolation devices similar to those
previously approved for other models would be acceptable, (2) that no
further changes to airplane wiring would be required, and (3) that the
design change would be required to protect only the center fuel tank.
Goodrich noted that protection for all fuel tanks is required for the
two similar ADs: AD 99-03-04, Amendment 39-11018 (64 FR 4959, February
2, 1999), for Model 737 airplanes; and AD 98-20-40, Amendment 39-10808
(63 FR 52147, September 30, 1998), for Model 747 airplanes. Goodrich
requested that we revise the cost estimate if the AD's intent is to
require protection for fuel tanks other than the center fuel tank or if
other wiring change requirements are anticipated. Goodrich stated that
the cost specified in the NPRM should be estimated based on the actual
design changes expected, rather than on previous AD actions.
We provide the following clarification of the intended scope of the
NPRM (77 FR 12506, March 1, 2012) and the associated cost estimate
regarding which fuel tanks are subject to the proposed requirements. AD
99-03-04, Amendment 39-11018 (64 FR 4959, February 2, 1999), and AD 98-
20-40, Amendment 39-10808 (63 FR 52147, September 30, 1998), affect
FQIS designs that are considered to have a higher level of risk of a
fuel tank ignition source than the systems used on Model 757 airplanes.
In addition, those systems were identical or nearly identical to the
FQIS that was determined by the NTSB to be the most likely cause of the
1996 Model 747-100 accident described in the NPRM. Because the latent-
plus-one failure scenario was suspected of actually having occurred on
that system type, we determined that corrective action for all fuel
tanks was appropriate. This decision was consistent with the
subsequently published FAA policy on SFAR 88 AD decision criteria
(section 25.981(a)(3) of the Federal Aviation Regulations (14 CFR
25.981(a)(3))) (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716)). Also, it was our understanding that the design of that FQIS
was such that, due to wiring interconnections between fuel tanks, it
was necessary to protect the circuits for all fuel tanks in order to
achieve effective protection for any one fuel tank.
We have determined that the FQIS used on earlier production Model
757 airplanes has the same fuel tank interconnection issue, but that
the Goodrich system used on later production Model 757 airplanes does
not have that issue. Since the cost estimates provided by both Boeing
and Goodrich were based on design solutions that included upgrading to
a Goodrich FQIS, we assume that the level of circuit protection for the
center fuel tank can be significantly increased relative to the
existing Goodrich design without having to further alter circuits or
wiring for the main fuel tanks (beyond the alterations necessary to
replace the FQIS with the Goodrich FQIS).
Because the latent-plus-one scenarios for Model 757 airplanes
equipped with the Goodrich FQIS are classified as ``theoretical''
rather than ``known to have occurred'' under the FAA policy on SFAR 88
AD decision criteria (section 25.981(a)(3) of the Federal Aviation
Regulations (14 CFR 25.981(a)(3))) (https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73716)), we have determined in
accordance with that policy that the corrective action for passenger
airplanes must eliminate the potential for all theoretical latent-plus-
one scenarios to create an ignition source in the center fuel tank,
which is classified under that policy as a high flammability fuel tank.
The need to modify the circuits or wiring for the main fuel tanks to
achieve that intent will depend on the proposed design solution and the
existing configuration of the airplane.
As stated previously, we have revised the cost estimate in this
SNPRM. For the purpose of the cost estimate for passenger airplanes, we
have assumed that the airplane will be upgraded to the Goodrich FQIS if
necessary, and any further modifications will be to only the center
fuel tank circuits or wiring. For the purpose of the additional
proposed cargo airplane option, we have provided separate estimates for
each design. For cargo airplanes equipped with the early 757 FQIS
design, we have assumed that additional isolation of some main fuel
tank wiring will be required. It is not necessary to change the
proposed requirement itself in paragraph (g) of this SNPRM, which is
very specific that protection is required for the center fuel tank.
Request To Revise Cost Estimate To Consider Long-Term Effect of AD
Goodrich asked whether the cost estimate specified in the NPRM (77
FR 12506, March 1, 2012) considers the expectation that the affected
fleet will be in operation for at least 20 more years, and that a
complete redesign of the FQIS would need to be considered to ensure the
availability of key FQIS electrical components. Goodrich stated this
concern could drive potential development costs higher.
We agree with the commenter's assertion. We did consider that the
affected fleet will be in service for a considerable period of time. In
the cost estimate in the NPRM (77 FR 12506, March 1, 2012), we assumed
that the existing FQIS could be modified to meet the intent of the AD.
However, comments from Boeing and Goodrich led us to recognize that it
was likely that operators of airplanes with the early 757 FQIS design
will likely need to be upgraded to the later Goodrich FQIS. The cost
estimates used in this SNPRM for the fully compliant FQIS option (as
opposed to the newly added cargo airplane option) are based on the
estimates provided by Boeing and Goodrich. We previously described
changes to the cost estimate in this SNPRM, but no further change is
necessary regarding this issue.
Request To Explain Delay in Rulemaking and Identify Planned SFAR 88 ADs
A4A requested that we explain the delay in rulemaking for this
issue, and identify any further planned SFAR 88 ADs. A4A asked why the
NPRM (77 FR 12506, March 1, 2012) was issued approximately 10 years
after the identification of the unsafe conditions and development of
design solutions was required to be completed under SFAR 88. A4A
further asked that the FAA provide information on any other
[[Page 9412]]
designs that were already reviewed under SFAR 88, and provide industry
with information regarding their planned disposition.
We have specifically discussed these issues in the preamble to the
FTFR rule (73 FR 42444, July 21, 2008) and the NPRM (77 FR 12506, March
1, 2012), and explained the reasons for the delay in the response to
``Request to Extend Compliance Time Pending Issuance of Service
Information'' in this SNPRM. We cannot provide additional information
on the results of design reviews and the planned disposition of issues
identified in those design reviews because that information is
proprietary. The FAA has not made available to the public an overall
list of the specific product issues identified and the plans to address
those issues, but operators can request the design review results from
the manufacturers. We will likely propose additional AD rulemaking, and
the public will be notified of those proposals via NPRMs. We have not
changed this SNPRM regarding this issue.
Request To Explain Timing of NPRM (77 FR 12506, March 1, 2012) and
Deficiencies of Affected Design
FedEx requested that we explain what is non-compliant about the
affected design and why we are proposing this design change at this
late date. FedEx stated that Boeing and Goodrich determined in their
safety reviews that only the FQIS densitometer was non-compliant.
We agree to provide further explanation. This SNPRM addresses the
question about the timing of this proposal under ``Request to Extend
Compliance Time Pending Issuance of Service Information'' in this
SNPRM. Boeing and Goodrich did identify that the densitometer of the
Goodrich system had the potential for a single failure to cause an
ignition source in a fuel tank. That issue was addressed by AD 2009-06-
20, Amendment 39-15857 (74 FR 12236, March 24, 2009). However, the
Boeing safety review and the FAA SFAR 88 AD Board also identified the
potential for a failure in airplane wiring outside the fuel tank or in
the FQIS processor unit that, combined with a pre-existing latent
failure of wiring or certain types of probe contamination inside the
fuel tank, could cause an ignition source. These identified failure
combinations were considered to be non-compliant with section 25.901(c)
of the Federal Aviation Regulations (14 CFR 25.901(c)) and section
25.981 of the Federal Aviation Regulations (14 CFR 25.981). We have not
changed this SNPRM regarding this issue.
Request for Independent Review Regarding Timeliness of AD
NATCA requested an independent review to identify and document how
this issue was allowed to go unaddressed for 16 years since the TWA
accident and 9 years since SFAR 88 required the development of service
information. The commenter requested that the findings from that review
be published.
We acknowledge that there have been significant delays in
addressing the issue that is the subject of this SNPRM. We are also
fully aware of the events and factors that have led to those delays. We
infer that NATCA made the request to ensure that the public is aware of
those events and factors. We have described those events and factors in
the NPRM (77 FR 12506, March 1, 2012) and in the other comment
responses included in this SNPRM, and therefore the FAA does not plan
to conduct the proposed review. We have not changed this SNPRM
regarding this issue.
Request To Clarify Compliance Times
A4A requested that we revise the NPRM (77 FR 12506, March 1, 2012)
to clarify that the compliance deadlines in the AD prevail over the
compliance deadlines in section 121.1117 of the Federal Aviation
Regulations (14 CFR 121.1117) for any airplane for which the operator
has chosen to comply with the AD by installing FRM.
The proposed compliance times reflect the desired interpretation of
the commenter as they pertain to cargo airplanes and airplanes that are
not operated per part 121, part 125, or part 129 of the Federal
Aviation Regulations (14 CFR part 121, 14 CFR part 125, or 14 CFR part
129). Passenger airplanes operating under part 121, part 125, or part
129 of the Federal Aviation Regulations (14 CFR part 121, 14 CFR part
125, or 14 CFR part 129) must meet the compliance deadlines established
in those operating rules. No change to this SNPRM is necessary
regarding this issue.
Request To Clarify Master Minimum Equipment List (MMEL) Relief
A4A requested that we revise the NPRM (77 FR 12506, March 1, 2012)
to clarify that the MMEL relief provided for the Boeing NGS also
applies to airplanes for which the operator has chosen to comply with
the AD by installing an FRM such as the Boeing NGS.
We acknowledge the commenter's concern. The revised applicability
statement in paragraph (c) of this SNPRM excludes airplanes that are
``equipped with a flammability reduction means (FRM) approved by the
FAA. . . .'' That exclusion does not state that the installed equipment
must be operative. However, installed equipment is required to be
operative by sections 121.628, 125.201, and 129.14 of the Federal
Aviation Regulations (14 CFR 121.628, 14 CFR 125.201, and 14 CFR
129.14) except as allowed by the MMEL and the operator's approved
minimum equipment list (MEL). Dispatch with an inoperative FRM under
the MMEL is not prohibited by the AD, and our intent is to allow such
operation. We have not further changed this SNPRM regarding this issue.
Request To Clarify Airplanes Excluded From Applicability
A4A requested that we revise the NPRM (77 FR 12506, March 1, 2012)
to clarify that airplanes equipped with FRM before conversion to all-
cargo operations are excluded from the proposed requirement to modify
the FQIS.
We agree to provide clarification. The revised applicability of
this SNPRM excludes airplanes for which operators have installed FRM.
No further change is necessary to this SNPRM regarding this issue. As
noted above, the FRM must be operational with the exception of any
relief granted under MMEL provisions.
Additional Change to NPRM (77 FR 12506, March 1, 2012)
We have removed NOTE 1 of the NPRM (77 FR 12506, March 1, 2012).
The note was included only as reminder that maintenance and/or
preventive maintenance under 14 CFR part 43 is permitted provided the
maintenance does not result in changing the AD-mandated configuration
(reference 14 CFR 39.7).
FAA's Determination
We are proposing this SNPRM because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.
Certain changes described above expand the scope of the NPRM (77 FR
12506, March 1, 2012). As a result, we have determined that it is
necessary to reopen the comment period to provide additional
opportunity for the public to comment on this SNPRM.
Proposed Requirements of the SNPRM
This SNPRM would require modifying the FQIS wiring or fuel tank
systems to prevent development of an ignition source inside the center
fuel tank.
[[Page 9413]]
Costs of Compliance
We estimate that this proposed AD affects 167 airplanes of U.S.
registry. This estimate includes 148 cargo airplanes and 19 non-air-
carrier passenger airplanes. We estimate the following costs to comply
with this proposed AD:
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Estimated Costs--Basic Proposed Requirement for All Airplanes
----------------------------------------------------------------------------------------------------------------
Fully correct FQIS vulnerability to 1,200 work-hours x $85 per $200,000 $302,000.
latent-plus-one failure conditions. hour = $102,000.
----------------------------------------------------------------------------------------------------------------
Estimated Costs--Optional Actions for All Airplanes
----------------------------------------------------------------------------------------------------------------
Install FRM........................... 720 work-hours x $85 per hour $323,000 $384,200.
= $61,200.
----------------------------------------------------------------------------------------------------------------
Estimated Costs--Optional Actions for Cargo Airplanes
----------------------------------------------------------------------------------------------------------------
Wire separation....................... 230 work-hours x $85 per hour $10,000 $29,550.
= $19,550.
FQIS BITE check (required with wire 1 work-hour x $85 per hour = 0 $85 per check (4 checks
separation option). $85. per year).
----------------------------------------------------------------------------------------------------------------
Existing regulations already require that air-carrier passenger
airplanes be equipped with FRM by December 26, 2017. We therefore
assume that the FRM installation specified in paragraph (g) of this
SNPRM would be done on only the 19 affected non-air-carrier passenger
airplanes, for an estimated passenger fleet cost of $5,738,000. We also
assume that the operators of the 148 affected cargo airplanes would
choose the less costly actions specified in paragraph (h) of this AD,
at an estimated cost of $4,373,400 for the wire separation
modification, plus $50,320 annually for the BITE checks.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. ``Subtitle VII: Aviation Programs''
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.
Regulatory Findings
We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship
between the national Government and the States, or on the distribution
of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify this proposed
regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
0
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):
The Boeing Company: Docket No. FAA-2012-0187; Directorate Identifier
2011-NM-094-AD.
(a) Comments Due Date
We must receive comments by April 24, 2015.
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company Model 757-200, -200PF, -
200CB, and -300 series airplanes; certificated in any category;
except airplanes equipped with a flammability reduction means (FRM)
approved by the FAA as compliant with the Fuel Tank Flammability
Reduction (FTFR) rule (73 FR 42444, July 21, 2008) requirements of
section 25.981(b) or section 26.33(c)(1) of the Federal Aviation
Regulations (14 CFR 25.981(b) or 14 CFR 26.33(c)(1)).
(d) Subject
Joint Aircraft System Component (JASC) Code 7397: Engine fuel
system wiring.
(e) Unsafe Condition
This AD was prompted by fuel system reviews conducted by the
manufacturer. We are issuing this AD to prevent development of an
ignition source inside the center fuel tank caused by a latent in-
tank failure combined with electrical energy transmitted into the
center fuel tank via the fuel quantity indicating system (FQIS)
wiring due to a single out-tank failure.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Modification
Within 72 months after the effective date of this AD, modify the
FQIS wiring or fuel tank systems to prevent development of an
ignition source inside the center fuel tank, using a method approved
in accordance with the procedures specified in paragraph (i) of this
AD.
(h) Optional Actions for Cargo Airplanes
For airplanes used exclusively for cargo operations: As an
option to the requirements of paragraph (g) of this AD, do the
actions
[[Page 9414]]
specified in paragraphs (h)(1) and (h)(2) of this AD, using methods
approved in accordance with the procedures specified in paragraph
(i) of this AD.
(1) Within 6 months after the effective date of this AD, record
the existing fault codes stored in the FQIS processor and then do a
BITE check (check of built-in test equipment) of the FQIS, in
accordance with the Accomplishment Instructions of Boeing Service
Bulletin 757-28-0136, dated June 5, 2014. If any fault codes are
recorded prior to the BITE check or as a result of the BITE check,
before further flight, do all applicable repairs and repeat the BITE
check until a successful test is performed with no faults found, in
accordance with Boeing Service Bulletin 757-28-0136, dated June 5,
2014. Repeat these actions thereafter at intervals not to exceed 750
flight hours.
(2) Within 72 months after the effective date of this AD, modify
the airplane by separating FQIS wiring that runs between the FQIS
processor and the center fuel tank, including any circuits that
might pass through a main fuel tank, from other airplane wiring that
is not intrinsically safe.
(i) Alternative Methods of Compliance (AMOCs)
(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested
using the procedures found in 14 CFR 39.19. In accordance with 14
CFR 39.19, send your request to your principal inspector or local
Flight Standards District Office, as appropriate. If sending
information directly to the manager of the ACO, send it to the
attention of the person identified in paragraph (j) of this AD.
Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
(2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager
of the local flight standards district office/certificate holding
district office.
(j) Related Information
For more information about this AD, contact Jon Regimbal,
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle
Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton,
Washington 98057-3356; phone: 425-917-6506; fax: 425-917-6590;
email: jon.regimbal@faa.gov.
Issued in Renton, Washington, on December 18, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2015-03540 Filed 2-20-15; 8:45 am]
BILLING CODE 4910-13-P