Airworthiness Directives; The Boeing Company Airplanes, 60048-60057 [2020-19809]
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Federal Register / Vol. 85, No. 186 / Thursday, September 24, 2020 / Rules and Regulations
appointed for 15-year terms as part of a
temporary expansion provision.
Hostages, Iraq, Kuwait, Lebanon, Life
insurance, Retirement.
Regulatory Procedures
Office of Personnel Management.
Alexys Stanley,
Regulatory Affairs Analyst.
OPM has examined the impact of this
rule as required by Executive Order
12866 and Executive Order 13563,
which directs agencies to assess all costs
and benefits of available regulatory
alternatives and, if regulation is
necessary, to select regulatory
approaches that maximize net benefits
(including potential economic,
environmental, public, health, and
safety effects, distributive impacts, and
equity). This rule is not a significant
regulatory action under Section 3(f) of
Executive Order 12866 and was not
reviewed by OMB.
Reducing Regulation and Controlling
Regulatory Costs
This final rule is not subject to the
requirements of E.O. 13771 (82 FR 9339,
February 2, 2017) because this final rule
is not significant under Executive Order
12866.
Regulatory Flexibility Act
The Office of Personnel Management
certifies that this regulation will not
have a significant economic impact on
a substantial number of small entities
because the regulation only affects a
small number of Federal employees and
annuitants.
Federalism
We have examined this rule in
accordance with Executive Order 13132,
Federalism, and have determined that
this rule will not have any negative
impact on the rights, roles and
responsibilities of State, local, or tribal
governments.
Paperwork Reduction Act of 1995 (44
U.S.C. Chapter 35)
The Paperwork Reduction Act of 1995
(44 U.S.C. chapter 3507(d); see 5 CFR
part 1320) requires that the U.S. Office
of Management and Budget (OMB)
approve all collections of information
by a Federal agency from the public
before they can be implemented.
Respondents are not required to respond
to any collection of information unless
it displays a current valid OMB control
number. OPM has determined this rule
does not impose additional reporting or
recordkeeping requirements under the
Paperwork Reduction Act of 1995
outside of an already approved existing
collection under OMB Control No:
3206–0230, Life Insurance Election.
List of Subjects in 5 CFR Part 870
Administrative practice and
procedure, Government employees,
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For the reasons stated in the
preamble, the Office of Personnel
Management amends 5 CFR part 870 as
follows:
PART 870—FEDERAL EMPLOYEES’
GROUP LIFE INSURANCE PROGRAM
1. The authority citation for part 870
continues to read:
■
Authority: 5 U.S.C. 8716; Subpart J also
issued under section 599C of Pub. L. 101–
513, 104 Stat. 2064, as amended; Sec.
870.302(a)(3)(ii) also issued under section
153 of Pub. L. 104–134, 110 Stat. 1321; Sec.
870.302(a)(3) also issued under sections
11202(f), 11232(e), and 11246(b) and (c) of
Pub. L. 105–33, 111 Stat. 251, and section
7(e) of Pub. L. 105–274, 112 Stat. 2419; Sec.
870.302(a)(3) also issued under section 145 of
Pub. L. 106–522, 114 Stat. 2472; Secs.
870.302(b)(8), 870.601(a), and 870.602(b) also
issued under Pub. L. 110–279, 122 Stat. 2604;
Subpart E also issued under 5 U.S.C. 8702(c);
Sec. 870.601(d)(3) also issued under 5 U.S.C.
8706(d); Sec. 870.703(e)(1) also issued under
section 502 of Pub. L. 110–177, 121 Stat.
Start Printed Page 773662542; Sec. 870.705
also issued under 5 U.S.C. 8714b(c) and
8714c(c); Public Law 104–106, 110 Stat. 521.
2. Amend § 870.101 by revising
paragraph (4) in the definition of
Employing Office, to read as follows:
■
§ 870.101
locality-based comparability payment
under 5 U.S.C. 5304; and
(iii) Any special pay supplement for
a defined subcategory of employees that
is equivalent to a special rate
supplement under 5 U.S.C. 5305.
(2) Notwithstanding paragraph (a) (1)
of this section, annual basic pay does
not include the following:
(i) Bonuses, allowances, overtime pay,
military pay, or any other pay to a
covered civilian employee given in
addition to the base pay of the position,
except as otherwise provided by specific
provision of law or OPM regulation.
(ii) Physicians comparability
allowances under 5 U.S.C. 5948.
*
*
*
*
*
■ 4. Amend § 870.703 by revising
paragraph (e)(1) introductory text and
adding paragraph (e)(1)(vii) to read as
follows:
§ 870.703
Election of Basic insurance.
*
*
*
*
*
(e)(1) For purposes of this part, a
judge who retires under paragraphs
(e)(1)(i) through (vii) of this section is
considered to be an employee after
retirement:
*
*
*
*
*
(vii) 38 U.S.C. 7296;
*
*
*
*
*
[FR Doc. 2020–18042 Filed 9–23–20; 8:45 am]
BILLING CODE 6325–38–P
DEPARTMENT OF TRANSPORTATION
Definitions.
*
*
*
*
*
Employing Office * * *
(4) The United States Court of
Appeals for Veterans Claims is the
employing office for judges of the
United States Court of Appeals for
Veterans Claims.
*
*
*
*
*
■ 3. Amend § 870.204 by revising
paragraph (a) to read as follows:
Federal Aviation Administration
§ 870.204
AGENCY:
Annual rates of pay.
(a)(1) An employee’s annual pay is the
annual basic pay of the position as fixed
by law or regulation, except as
otherwise provided by specific
provision of law or OPM regulation.
Annual pay for this purpose includes
the following:
(i) Any pay of a type that is treated as
basic pay for purposes of the retirement
systems established under 5 U.S.C.
chapters 83 and 84, consistent with 5
U.S.C. 8331(3), and pay that is annual
pay for purposes of the FEGLI Program
as provided in Federal law and
regulation;
(ii) Any geographic-based pay
supplement that is equivalent to a
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14 CFR Part 39
[Docket No. FAA–2016–6139; Product
Identifier 2015–NM–061–AD; Amendment
39–21234; AD 2020–18–13]
RIN 2120–AA64
Airworthiness Directives; The Boeing
Company Airplanes
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
The FAA is adopting a new
airworthiness directive (AD) for certain
The Boeing Company Model 737–600,
–700, –700C, –800, –900, and –900ER
series airplanes. This AD was prompted
by the FAA’s analysis of the Model 737
fuel system reviews conducted by the
manufacturer. This AD requires
modifying the fuel quantity indicating
system (FQIS) to prevent development
of an ignition source inside the center
fuel tank due to electrical fault
conditions. This AD also provides
alternative actions for cargo airplanes.
SUMMARY:
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The FAA is issuing this AD to address
the unsafe condition on these products.
DATES: This AD is effective October 29,
2020.
ADDRESSES:
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–2016–
6139; or in person at Docket Operations
between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
The AD docket contains this final rule,
any comments received, and other
information. The address for Docket
Operations is U.S. Department of
Transportation, Docket Operations, M–
30, West Building Ground Floor, Room
W12–140, 1200 New Jersey Avenue SE,
Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT: Jon
Regimbal, Aerospace Engineer,
Propulsion Section, FAA, Seattle ACO
Branch, 2200 South 216th St., Des
Moines, WA 98198; phone and fax: 206–
231–3557; email: Jon.Regimbal@faa.gov.
SUPPLEMENTARY INFORMATION:
Discussion
The FAA issued a notice of proposed
rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would
apply to certain The Boeing Company
Model 737–600, –700, –700C, –800,
–900, and –900ER series airplanes. The
NPRM published in the Federal
Register on May 3, 2016 (81 FR 26485).
The NPRM was prompted by the FAA’s
analysis of the Model 737 fuel system
reviews conducted by the manufacturer.
The NPRM proposed to require
modifying the FQIS to prevent
development of an ignition source
inside the center fuel tank due to
electrical fault conditions. The NPRM
also proposed to provide alternative
actions for cargo airplanes.
The FAA is issuing this AD to address
ignition sources inside the center fuel
tank, which, in combination with
flammable fuel vapors, could result in a
fuel tank explosion and consequent loss
of the airplane.
Comments
The FAA gave the public the
opportunity to participate in developing
this final rule. The following presents
the comments received on the NPRM
and the FAA’s response to each
comment.
Support for the NPRM
The Air Line Pilots Association,
International (ALPA) and National Air
Traffic Controllers Association
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(NATCA) supported the intent of the
NPRM. Additional comments from
NATCA are addressed below.
Request To Withdraw NPRM:
Unjustified by Risk
Airlines for America and the Cargo
Airline Association, in consolidated
comments (A4A/CAA), and KLM Royal
Dutch Airlines (KLM) requested that the
FAA withdraw the NPRM. A4A/CAA
cited comments submitted by Boeing to
Docket No. FAA–2012–0187 in which
Boeing stated that the risk is ‘‘less than
extremely improbable’’ and that Boeing
does not believe that an unsafe
condition exists. A4A/CAA noted that
they consider the Boeing comments to
be applicable to the airplane models in
the NPRM. KLM stated that the NPRM
does not clarify the necessity of
additional actions beyond current
requirements. KLM added that it
understands that Boeing is not able to
explain or substantiate the rationale
behind the NPRM.
The FAA disagrees with the
commenters’ request. The FAA notes
that Boeing’s comments were addressed
in the supplemental NPRM (SNPRM) for
Docket No. FAA 2012–0187 (80 FR
9400, February 23, 2015) in the
comment response for ‘‘Request To
Withdraw NPRM (77 FR 12506, March
1, 2012): Unjustified by Risk.’’ As
explained in that comment response, in
addition to examining average risk and
total fleet risk, the FAA examines the
individual flight risk on the worst
reasonably anticipated flights. In
general, the FAA issues 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. The FAA has determined that
the current requirements, including
airworthiness limitations and critical
design configuration control limitations
(CDCCLs) do not adequately address the
unsafe condition identified in this AD
and therefore it is necessary to issue this
final rule. The FAA has not changed
this AD regarding this issue.
Request To Withdraw NPRM:
Probability Analysis Inconsistent With
Regulatory Requirements
A4A/CAA requested that the FAA
withdraw the NPRM. A4A/CAA stated
that the assumption of a single failure
regardless of probability is inconsistent
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with 14 CFR part 25 regulatory
requirements. A4A/CAA referred to the
phrase ‘‘regardless of probability’’
associated with single failures. A4A/
CAA acknowledged that the term is
used with single failures in FAA
Advisory Circular (AC) 25.981–1C,1
‘‘Fuel Tank Ignition Source Prevention
Guidelines,’’ but since that term does
not appear in 14 CFR 25.981(a)(3), the
commenter considered its use arbitrary,
possibly introducing additional
requirements not included in that
section. A4A/CAA stated that the
‘‘worst reasonably anticipated flight’’ is
a flight with a latent FQIS failure and a
high-flammability tank, and this ‘‘latent
plus one’’ failure—regardless of
probability of a single failure—is not
consistent with 14 CFR 25.981(a)(3).
The FAA disagrees with the
commenter’s request. The FAA notes
that the commenter’s assertion about the
intent of 14 CFR 25.981(a)(3) is incorrect
based on both the language of the rule
and on the published rulemaking
documents. The absence of a
probabilistic qualifier in both the ‘‘from
each single failure’’ clause and in the
‘‘from each single failure in combination
with each latent failure not shown to be
extremely remote’’ clause in 14 CFR
25.981(a)(3) in fact means just that—
there is no probabilistic qualifier
intended by the regulation. The intent
for single failures in these two scenarios
to be considered regardless of
probability of the single failure was
explicitly stated in the NPRM for 14
CFR 25.981, as amended by amendment
25–102 (66 FR 23085, May 7, 2001)
(‘‘amendment 25–102’’). That NPRM
stated, in pertinent part, that it would
also add a new paragraph (a)(3) to
require that a safety analysis be
performed to demonstrate that the
presence of an ignition source in the
fuel tank system could not result from
‘‘any single failure, from any single
failure in combination with any latent
failure condition not shown to be
extremely remote, or from any
combination of failures not shown to be
extremely improbable.’’ These new
requirements would define three
scenarios that must be addressed in
order to show compliance with the
proposed paragraph (a)(3). ‘‘The first
scenario is that any single failure,
regardless of the probability of
occurrence of the failure, must not cause
an ignition source. The second scenario
is that any single failure, regardless of
the probability occurrence, in
combination with any latent failure
condition not shown to be at least
1 https://www.faa.gov/documentLibrary/media/
Advisory_Circular/AC_25.981-1C.pdf.
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Federal Register / Vol. 85, No. 186 / Thursday, September 24, 2020 / Rules and Regulations
extremely remote (i.e., not shown to be
extremely remote or extremely
improbable), must not cause an ignition
source. The third scenario is that any
combination of failures not shown to be
extremely improbable must not cause an
ignition source.’’
The preamble to the final rule for
amendment 25–102 made a nearly
identical statement, including the same
uses of the phrase ‘‘regardless of
probability.’’ The FAA has determined
that it is necessary to proceed with
issuance of this final rule as proposed.
Further details and a description of the
FAA’s risk assessment can be found in
responses to similar comments in a
related SNPRM that addressed the same
unsafe condition for Model 757
airplanes, in Docket No. FAA–2012–
0187, and in the subsequently issued
final rule, AD 2016–07–07, amendment
39–18452 (81 FR 19472, April 5, 2016)
(‘‘AD 2016–07–07’’). No change to this
AD was made in response to these
comments.
Request To Withdraw NPRM: No New
Data Since Fuel Tank Flammability
Reduction (FTFR) Rulemaking
A4A/CAA requested that the FAA
withdraw the NPRM based on a lack of
new data since the issuance of the FTFR
rule (73 FR 42444, July 21, 2008). A4A/
CAA referred to the FTFR rule and
decision to not require flammability
reductions means (FRM) for all-cargo
airplanes, and the FAA’s intent to gather
additional data and consideration of
further rulemaking if flammability of
these airplanes is excessive. A4A/CAA
stated that since the FTFR rule, no
additional data has been publicly
introduced that would support or justify
the applicability of this rulemaking to
all-cargo aircraft. A4A/CAA also
referred to the FAA’s response to
comments in the preamble to the
SNPRM for Docket No. FAA–2012–
0187, which documented the FAA’s
decision on applicability of FRM and
cost estimates. A4A/CAA stated that the
FAA response was misleading and not
factual since manufacturers did not
begin detailed designs to address the
proposed unsafe condition until after
the FTFR rule was published. A4A/CAA
added that the FAA did not discuss
other changes to the FQIS system in the
FTFR rule.
The FAA disagrees with the
commenter’s request. The FAA notes
that the FTFR rule and FQIS ADs are
two different issues with separate FAA
actions. The intent of the FTFR rule was
to provide an order of magnitude
reduction in the rate of fuel tank
explosions for the airplanes affected by
that rule through adding a new
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airworthiness standard for the
flammability of fuel tanks. The FAA
notes that the FTFR rule was never
intended to be a replacement for the
issuance of ADs to address identified
unsafe conditions. An unsafe condition
due to the identified FQIS latent-plussingle failure issue in high-flammability
fuel tanks was determined to exist
during the Special Federal Aviation
Regulation (SFAR) 88 AD Board held by
the FAA in 2003 using the guidance in
FAA Policy Memorandum ANM100–
2003–112–15, ‘‘SFAR 88—Mandatory
Action Decision Criteria,’’ dated
February 25, 2003,2 for highflammability fuel tanks, including the
center fuel tank on Model 737–600,
–700, –700C, –800, –900, and –900ER
series airplanes. That same issue was
not considered to be an unsafe
condition in low-flammability wing fuel
tanks based on that same policy
memorandum. The FAA has not
changed this AD regarding this issue.
Request To Withdraw NPRM: Arbitrary
and Inconsistent Wire Separation
Standards
A4A/CAA requested that the FAA
withdraw the NPRM based on a lack of
consistent design standards for FQIS
wire separation. A4A/CAA assumed
that the approved standard for the
retrofit is a 2-inch wire separation
minimum, which the commenter
considered arbitrary and inconsistently
applied. A4A/CAA reported that the
amount of wiring capable of meeting
that separation standard varies widely
among airplane models. A4A/CAA also
acknowledged that other separation
methods were used in areas not meeting
the 2-inch wire separation requirement.
The FAA does not agree with the
commenter’s request. The degree of
physical isolation of FQIS wiring from
other wiring, whether provided by
physical distance or barrier methods,
that is necessary to eliminate the
potential for hot shorts due to wiring
faults is dependent on the materials
used, the wire securing methods, and
the possible types of wiring faults. The
FAA relied on the manufacturer to
assess the details of the design and to
propose the appropriate isolation
measures. While 2 inches of physical
separation may appear to be an arbitrary
number, it was the distance proposed by
the manufacturer as appropriate for
their design based on analysis of the
design details. The FAA has not
changed this AD regarding this issue.
2 https://rgl.faa.gov/Regulatory_and_Guidance_
Library/rgPolicy.nsf/0/
dc94c3a46396950386256d5e006aed11/$FILE/
Feb2503.pdf.
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Request To Withdraw NPRM: NPRM
Arbitrary and Inconsistently Applied
A4A/CAA requested that the FAA
withdraw the NPRM. A4A/CAA noted
that airplanes with FRM are not
included in the applicability, and the
NPRM would therefore not fully address
the unsafe condition. A4A/CAA added
that the distinction between high- and
low-flammability exposure time fuel
tanks as used in the NPRM is arbitrary.
A4A/CAA stated that an arbitrary
differentiation of high- versus lowflammability as decisional criteria for
the need for corrective action does not
take into account the actual probability
of the impact of the difference in
flammability on the potential of
catastrophic failure. A4A/CAA also
stated that allowing the proposed
alternative actions for cargo airplanes
does not fully address the unsafe
condition in the NPRM. A4A/CAA
referenced the FAA’s response to
comments in AD 2016–07–07 regarding
this issue. The commenter summarized
numerical analysis showing no
significant difference in risk between
high- and low-flammability fuel tanks.
A4A/CAA concluded that the FAA’s
risk analysis is arbitrary and an unsafe
condition does not exist.
The FAA disagrees with the assertion
that the NPRM is arbitrary and
inconsistent. The NPRM follows defined
policy in FAA Policy Memorandum
ANM100–2003–112–15, and
consistently applies the policy to
several airplane models with similar
unsafe conditions, similar to AD 2016–
07–07. The FAA defined the difference
between low- and high-flammability
exposure time fuel tanks based on
recommendations from the Aviation
Rulemaking Advisory Committee Fuel
Tank Harmonization Working Group
(FTHWG). The preamble to the final
rule for amendment 25–102, which
amended 14 CFR 25.981, defined this
difference as based upon comparison of
‘‘the safety record of center wing fuel
tanks that, in certain airplanes, are
heated by equipment located under the
tank, and unheated fuel tanks located in
the wing.’’ The FTHWG concluded that
the safety record of fuel tanks located in
the wings was adequate and that if the
same level could be achieved in center
wing fuel tanks, the overall safety
objective would be achieved.
In the response to comments in the
preamble to the final rule for AD 2016–
07–07 referenced by the commenter, the
FAA described why FRM or alternative
actions for cargo airplanes provide an
acceptable level of safety, even if they
do not completely eliminate the noncompliance with 14 CFR 25.981(a)(3).
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The fuel tank explosion history for
turbojet/turbofan powered transport
airplanes fueled with kerosene type
fuels, outside of maintenance activity,
has consisted of explosions of tanks that
(1) are not conventional aluminum wing
tanks and (2) spend a considerable
amount of their operating time empty.
The service history of conventional
aluminum wing tanks has been
acceptable. The intent of the difference
in decision criteria in FAA Policy
Memorandum ANM100–2003–112–15
was intended to give credit for this
satisfactory service experience, and to
differentiate between tanks with a level
of flammability similar to that of a
conventional wing tank and those with
a significantly higher level of
flammability.
The numerical analysis provided by
the commenter is inconsistent with the
fuel tank explosion service history.
There are at least three identifiable
physics-based reasons for that
inconsistency. First, low-flammability
tanks on most types of airplanes are
main tanks that are the last tanks used.
During a large portion of their operating
time, the systems and structural features
that have the potential to be ignition
sources in the event of a failure
condition are covered with liquid fuel,
and an ignition source, if it occurs, is
likely to be submerged. When a
potential ignition source in a main tank
is uncovered, it is likely to be later in
the flight when the tank is cool and no
longer flammable. The commenter’s
analysis does not account for this
significant effect. Second, the numerical
analysis used by the commenter
assumes that any given ignition source
has a random occurrence in time at the
estimated probability, and that, in order
for an explosion to occur, that random
occurrence of an ignition source needs
to coincide with the tank being in a
flammable state. In fact, many of the
identified ignition threats do not simply
occur briefly and then go away. Instead,
a fault occurs that, until it is discovered
and corrected, repeatedly creates an
ignition source, and repeatedly tests
whether flammable conditions exist.
Third, the flammability of lowflammability fuel tanks is typically
dependent on weather, and a lowflammability fuel tank may operate for
months without ever becoming
flammable. This is not true of most
high-flammability fuel tanks, which
typically have significant on-airplane
heat sources driving their temperature.
This factor can mean that, on some
airplanes, an in-tank latent failure can
occur and, after some period of time, be
detected and corrected without the lowflammability tank ever having
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flammable conditions. The numerical
analysis provided by the commenter
does not account for these significant
factors. The difference in likelihood of
a failure that results in repeated ignition
source events causing a tank explosion
is not simply proportional to difference
in the fleet average flammability of the
tank for the reasons stated above. The
FAA has not changed this AD regarding
this issue.
Request To Withdraw NPRM:
Overestimate of Fleet Average
Flammability Exposure for All-Cargo
Fleet in Alaska
A4A/CAA requested that the FAA
withdraw the NPRM. The commenter
stated that the FAA did not properly
analyze the fleet average flammability
for the center wing tank on Model 737–
700 airplanes. The commenter stated
that the known U.S. registered 737–700
all-cargo fleet without FRM installed
will be operated almost solely in the
state of Alaska for the foreseeable future.
A4A/CAA noted that the mean average
ambient temperature in Alaska is much
lower than that used in the FAA’s
analysis. The commenter added that the
air conditioning packs in an all-cargo
configuration generate significantly less
heat transfer to the center wing tank
during normal operations than during
the normal operations assumed by the
FAA’s analysis. A4A/CAA concluded
that these factors reduce the fleet
average flammability exposure for the
all-cargo Model 737–700 airplanes to
the level of the main wing tanks, and
therefore, the unsafe condition does not
exist.
The FAA does not agree to withdraw
the NPRM. More than 1,100 Model 737–
700 airplanes have been produced. The
FAA foresees that, as these airplanes are
replaced in passenger service by newer
airplanes, a significant portion of them
will be converted to all-cargo service
and will eventually fly throughout the
U.S. and the world. Multiple cargoconversion designs for these airplanes
have been approved, and other
conversion designs are in the approval
process. The FAA does not agree to base
its decision about whether an AD is
necessary for these airplanes on a
flammability analysis based solely on
the initial cargo conversions currently
being largely operated in Alaska.
The FAA also does not agree that a
new analysis considering operation of
only the initial cargo-converted
airplanes would result in a
determination that the center fuel tank
of those airplanes has a level of
flammability comparable to a wing tank
of conventional aluminum construction,
and that the center fuel tank on those
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60051
airplanes could therefore legitimately be
classified as a low-flammability fuel
tank. In addition, the FAA considers the
unsafe condition determination
described in the SNPRM for Docket No.
FAA–2012–0187, in the response to
comments section under, ‘‘Request To
Withdraw NPRM (77 FR 12506, March
1, 2012): Unjustified by Risk,’’ to be
applicable to these Model 737 airplanes.
Request To Remove Certain Business
Jets From the Applicability
AMES Continuing Airworthiness
Management Organization (AMES
CAMO) requested that the proposed AD
be revised to exclude Boeing Business
Jets operated under 14 CFR part 91.
AMES CAMO noted that the proposed
AD excludes airplanes modified by the
nitrogen generation system (NGS)
system, but the NGS is mandated only
on commercial airplanes operating
under 14 CFR part 121. AMES CAMO
suggested the proposed AD should only
apply to airplanes operating under 14
CFR part 121.
The FAA disagrees with the
commenter’s request. Policy
Memorandum ANM100–2003–112–15 is
applicable to large transport airplanes
except those specifically excluded by
the Special Federal Aviation Regulation
(SFAR) No. 88 regulation (in 14 CFR
part 21). The FAA did not exclude nonair-carrier large transport airplanes from
the other ADs determined to be
necessary as a result of SFAR 88, and
included non-air-carrier large transport
airplanes in the FRM retrofit
requirements added to 14 CFR part 125
in 2008. The unsafe condition addressed
by this AD is applicable to Model 737
airplanes operated as business jets,
except as specified in paragraph (c) of
this AD. The FAA has not changed this
AD regarding this issue.
Request To Require Cargo Airplane
Option for All Airplanes
Boeing and All Nippon Airways
(ANA) requested that the NPRM be
revised to make the alternative actions
for cargo airplanes specified in
paragraph (h) of the proposed AD
applicable to all airplanes. Boeing asked
that the FAA provide a technical
justification why the actions in
paragraph (h) of the proposed AD apply
only to cargo airplanes. ANA asked that
the actions in paragraph (h) of the
proposed AD be allowed for passenger
airplanes not subject to the FTFR rule,
suggesting this would provide more
choices regarding how to comply with
the proposed AD.
The FAA disagrees with the
commenters’ requests. As discussed in
the comment response in the SNPRM
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for Docket No. FAA–2012–0187, under
the heading ‘‘Requests To Withdraw
NPRM (77 FR 12506, March 1, 2012)
Based on Applicability’’ the FAA does
not consider the alternative action for
cargo airplanes allowed by this AD to
provide an adequate level of safety for
passenger airplanes. The FAA is willing
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 not changed this AD regarding this
issue.
Request To Exclude Certain Airplanes
United Airlines (UAL) noted that the
FRM required by 14 CFR 121.1117 will
have been installed on all affected
airplanes in passenger configuration by
December 26, 2018. The FAA infers
UAL is requesting that the FAA revise
the proposed AD to exclude airplanes
that are affected by 14 CFR 121.1117. In
addition, UAL suggested that the FAA
either delete paragraph (g) of the
proposed AD or make paragraph (g) of
the proposed AD applicable only to
airplanes in a cargo configuration that
do not have an FRM installed and nonU.S.-registered airplanes that do not
have to comply with FRM requirements.
The FAA disagrees with the
commenter’s request. There are other
passenger-carrying airplanes operated
under 14 CFR part 91 that are not
required to install FRM. (The
requirement to install FRM on all
passenger-carrying airplanes operated
by air carriers is in 14 CFR 121.1117.)
The FAA notes that foreign air carriers
may not have to comply with that
requirement or similar requirements of
their own civil aviation authority. The
European Union Aviation Safety Agency
(EASA), for example, has chosen not to
require FRM to be retrofitted to inservice airplanes. This AD is intended
to require any Model 737–600, –700,
–700C, –800, –900, and –900ER series
passenger airplane that does not have
FRM, regardless of the rules under
which it is operated, to address the
FQIS latent-plus-one unsafe condition
with a corrective action that fully
complies with the FAA’s airworthiness
standards. This requirement fulfills the
FAA’s International Civil Aviation
Organization to address unsafe
conditions on all of the aircraft
manufactured by the state of design, not
just those aircraft whose operation is
under the jurisdiction of the state of
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design. The FAA has not changed this
AD regarding this issue.
Request To Clarify Certification Basis
for Modification Requirements
NATCA recommended that the FAA
revise paragraph (g) of the proposed AD
to clearly state that the required FQIS
design changes must comply with the
fail-safe requirements of 14 CFR
25.901(c), as amended by amendment
25–46 (43 FR 50597, October 30, 1978);
and 14 CFR 25.981(a) and (b), as
amended by amendment 25–102;
NATCA added that these provisions are
required by SFAR 88.
The FAA does not agree to change
paragraph (g) of this AD. While the FAA
agrees that modifications to comply
with paragraph (g) of this AD should be
required to comply with the referenced
regulations, that requirement already
exists in 14 CFR part 21. No change to
this AD is necessary.
Request To Address Unsafe Condition
on All Fuel Tanks
NATCA recommended that the FAA
require design changes that eliminate
unsafe FQIS failure conditions on all
fuel tanks on the affected models,
regardless of fuel tank location or the
percentage of time the fuel tank is
flammable. NATCA referred to four fuel
tank explosions in low-flammability
exposure time fuel tanks identified by
the FAA during FTFR rulemaking.
NATCA stated that neither FRM nor
alternative actions for cargo airplanes
(e.g., BITE checks (checks of built-in test
equipment) followed by applicable
repairs before further flight and
modification of the center fuel tank
FQIS wiring within 60 months) would
bring the airplane into full regulatory
compliance. NATCA added that the
combination of failures described in the
NPRM meets the criteria for ‘‘known
combinations’’ of failures that require
corrective action in FAA Policy
Memorandum ANM100–2003–112–15.
The FAA disagrees with the
commenter’s request. The FAA has
determined that according to Policy
Memorandum ANM100–2003–112–15,
the failure condition for the airplanes
affected by this AD should not be
classified as a ‘‘known combination.’’
While the FQIS design architecture is
similar to that of the early Boeing Model
747 configuration that is suspected of
contributing to the TWA Flight 800 fuel
tank explosion, significant differences
exist in the design of FQIS components
and wire installations between the
affected Boeing models and the early
Model 747 airplanes such that the intent
of the ‘‘known combinations’’ provision
for low-flammability fuel tanks in the
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policy memorandum is not applicable.
Therefore, this AD affects only the
identified Boeing airplanes with highflammability exposure time fuel tanks,
as specified in paragraph (c) of this AD.
The FAA provided a detailed response
to similar comments in the preamble of
the final rule for AD 2016–07–07. The
FAA has not changed this final rule
regarding this issue.
Request To Require Modification on All
Production Airplanes
NATCA recommended that the FAA
require designs that comply with 14
CFR 25.901(c) and 25.981(a)(3) on all
newly produced transport airplanes.
NATCA stated that continuing to grant
exemptions to 14 CFR 25.901(c), as
amended by amendment 25–40 (42 FR
15042, March 17, 1977); and 14 CFR
25.981(a)(3), as amended by amendment
25–102; has allowed continued
production of thousands of airplanes
with this known unsafe condition.
The FAA disagrees with the
commenter’s request. The
recommendation to require production
airplanes to fully comply with 14 CFR
25.901(c) and 14 CFR 25.981(a)(3) is
outside the scope of this rulemaking. In
addition, the FAA has implemented
requirements for all large transport
airplanes produced after September
2010 to include flammability reduction
methods for tanks that would otherwise
be high-flammability fuel tanks. Boeing
incorporated this change into the Model
737 series airplanes that are still in
production and the FAA has excluded
those models from the applicability of
this AD. The FAA has not changed this
final rule regarding this issue.
Request To State That an Exemption is
Required
Boeing requested that paragraph (h) of
the proposed AD be revised to state that
an exemption is required to accomplish
the specified actions. Boeing stated that
the FAA has identified that the BITE
procedure and wire separation design
changes specified in the proposed AD
are not sufficient for compliance to 14
CFR 25.981(a) at the FQIS level. Boeing
stated that an exemption is therefore
needed prior to approval of the related
design change.
The FAA agrees to clarify. The BITE
check is not a type design change or
alteration, so no exemption from the
airworthiness standards is required for
that action. The design data approval of
any partial wire separation modification
would require an exemption. That
exemption would be obtained by the
party seeking approval of the alteration
data, and no further exemption would
be required for the party using that data
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to alter an aircraft. Obtaining such an
exemption would be part of the
certification process for such a change,
so, the FAA does not find it necessary
to include such information in
paragraph (h) of this AD. In addition,
some parties may choose to comply
with the AD using a design change that
fully complies with the airworthiness
standards. The FAA also notes that the
commenter appears to misunderstand
why an exemption is needed for the
required modification. The exemption is
needed because, even with the
modification, the FQIS does not comply
with 14 CFR 25.901(c) and 14 CFR
25.981(a). The exemption does not
authorize evaluation of a partial system
for compliance with the system level
requirement. The FAA has not changed
this AD regarding this issue.
Request To Exclude Airplanes That
Have Installed an Ignition Mitigation
Means (IMM) or Flammability Impact
Mitigation Means (FIMM)
AerSale stated that the Costs of
Compliance section of the NPRM only
cites the requirements in 14 CFR
121.1117 to install FRM, but 14 CFR
121.1117 paragraph (d)(1) states that
IMM, FRM, or FIMM may be installed.
AerSale suggested that all IMM, FRM, or
FIMM installations with the approval of
the FAA Oversight Office would meet
the requirements of 14 CFR 121.1117.
The FAA infers AerSale is requesting
that the proposed AD be revised to
exclude airplanes on which IMM or
FIMM has been installed.
The FAA partially agrees with the
commenter’s request. The FAA agrees
that IMM provides a level of risk
reduction at least as great as that
provided by FRM. The FAA does not
agree that airplanes should be excluded
from paragraph (c) of this AD based on
the installation of FIMM alone. FIMM is
applicable to design changes only, and
is intended to ensure that, if a fuel tank
design change would otherwise have
increased the flammability of a fuel
tank, the associated FIMM would ensure
that the flammability of that tank is not
increased by the design change.
Therefore, FIMM itself does not address
the need for FRM for the original tank
design. The FAA has revised paragraph
(c) of this AD to clarify that airplanes
with an IMM approved by the FAA as
compliant with certain regulations are
excluded from this AD. This revision
includes adding paragraphs (c)(1) and
(2) of this AD.
Request To Record Only Certain Codes
Boeing requested that paragraph (h)(1)
of the proposed AD be revised to only
require corrective actions if a
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nondispatchable fault code pertaining to
the center wing tank is recorded (as
opposed to any nondispatchable fault
code being recorded). Boeing stated that
all FQIS wire separation changes in the
proposed AD are limited to the center
wing tank, therefore only built-in test
equipment (BITE) check messages
pertaining to the center wing tank are
applicable to the proposed AD. In
addition, Boeing stated that a final rule
should be postponed until the FAA
develops a list of ‘‘nondispatchable fault
codes’’ in conjunction with Boeing.
The FAA agrees that the unsafe
condition addressed by this AD is
limited to the center wing tank.
However, the FAA does not agree that
the AD should be changed as proposed
by Boeing. It is not clear to the FAA
whether there may be FQIS BITE fault
codes that are not clearly identified as
related to the center wing tank but that
may impact center tank circuits.
Therefore, the FAA has determined that
all nondispatchable fault codes recorded
prior to the BITE check or as a result of
the BITE check required by paragraph
(h)(1) of this AD must be addressed.
Operators or Boeing may request an
alternative method of compliance
(AMOC) under the provisions of
paragraph (i) of this AD if they can
provide sufficient data that a particular
fault code does not pertain to the unsafe
condition addressed by this AD.
Regarding the requirement to record
and address fault codes read
immediately prior to running the BITE
check procedure, the FAA notes that the
normal Boeing procedure for performing
an FQIS BITE check is to first erase all
of the existing fault codes, then perform
the BITE check and troubleshoot any
resulting new fault codes. For this AD,
the FAA did not want any already
stored fault codes to be potentially
ignored due to erasure at the first step
because some of the failures of concern
can be intermittent. This AD therefore
requires operators to record the existing
codes before doing the BITE check, then
do the BITE check and record the new
codes that result from that BITE check,
and then do the appropriate
troubleshooting and corrective action
for both sets of codes per the
manufacturer’s guidance. The FAA has
not changed this AD regarding this
issue.
Finally, the FAA does not agree to
delay the final rule while Boeing
proposes and obtains FAA agreement on
a list of nondispatchable fault codes.
The FAA requested service information
from Boeing in 2016 to support the
option for all-cargo airplanes on all of
the Boeing models for which similar
FQIS ADs were planned. Boeing chose
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60053
at that time to develop service
information only for the Model 747–
400, 757, and 767 airplanes because at
that time only those airplanes had
affected cargo configuration for which
Boeing was the design approval holder.
The FAA agreed at that time to not
require Boeing to develop a BITE check
service bulletin for the Model 737
airplanes because Boeing had not yet
developed a cargo conversion service
bulletin or supplemental type certificate
(STC) for the Model 737 airplanes. The
FAA also considered that, because the
BITE check instructions already existed
in the Model 737 AMM, a BITE check
service bulletin could be developed
quickly at a later date if needed. In
addition, the process for obtaining FAA
agreement on a list of nondispatchable
fault codes for the models Boeing chose
to support took less than 30 days. If any
service information is developed to
support compliance with paragraph (h)
of this AD it will be evaluated for
approval using the AMOC process
specified in paragraph (i) of this AD.
Request To Clarify Required
Modification
ANA and Thomson Airways
requested that the FAA provide
clarification regarding how to
accomplish the modification specified
in paragraph (g) of the proposed AD.
ANA noted that paragraph (h) of the
proposed AD provides clear alternative
actions for cargo airplanes. ANA stated
that it could not identify how to modify
the FQIS in passenger airplanes not
subject to the FTFR rule. ANA noted
that it contacted Boeing for clarification
and Boeing stated that the FRM (which
Boeing calls NGS) retrofit is the method
of compliance for these airplanes. ANA
asked that the FAA either clarify how to
modify the FQIS system or accept an
FRM retrofit as terminating action.
Thomson Airways asked if the intent of
the proposed AD is to install an NGS on
affected airplanes. Thomson Airways
also asked for clarification regarding the
FQIS modification, stating that the
proposed AD does not provide detail
regarding modifying the FQIS itself,
only the FQIS wiring.
The FAA agrees to clarify. As noted
in paragraph (c) of this AD, airplanes on
which FRM or IMM that meets certain
FAA airworthiness standards is
installed are excluded from this AD.
Paragraph (g) of this AD requires
modification of the FQIS on passenger
airplanes to prevent development of an
ignition source inside the center fuel
tank due to electrical fault conditions.
The specifics of this modification may
vary as long as the modification
addresses the unsafe condition
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identified in this AD and the procedures
specified in paragraph (i) of this AD are
used to approve the modification
method. Operators may choose to install
an FRM or IMM that meets the criteria
specified in paragraph (c), which would
then remove that airplane from the
applicability of this AD, negating the
need to do the modification specified in
paragraph (g) of this AD. Otherwise,
operators must obtain an AMOC as
specified in paragraph (i) of this AD and
modify their airplane accordingly. The
FAA has not changed this AD regarding
this issue.
Request To Provide a Detailed CostEffective Method of Compliance
Korean Air Lines (KAL), KLM, AMES
CAMO, and Duco Schiere requested that
the FAA provide a detailed and costeffective method of compliance for
passenger airplanes. KAL, AMES
CAMO, and Duco Schiere noted that the
proposed AD does not provide a clear
means of compliance for the
modification, such as a Boeing service
bulletin. AMES CAMO noted that
without a clear method of compliance,
it is difficult to determine the extent of
the required work. KAL and KLM noted
that the majority of non-FAA operators
are not required to retrofit the NGS
system. KLM stated that since 2008 the
level of fuel tank safety has been
improved by the implementation of
several costly SFAR 88 service bulletins,
implementation of airworthiness
limitations into the maintenance
program and implementation of CDCCLs
into maintenance documents. KLM
mentioned that the modification would
require an airplane to be out of service
for a lengthy time. KLM added that the
modification would add weight to the
airplane and require additional fuel
usage. KAL and KLM requested that the
FAA encourage Boeing to develop an
acceptable cost-effective method of
compliance that does not require
installation of an NGS.
The FAA agrees that the lack of
service information for FQIS
modifications makes it difficult to assess
the required work to modify the FQIS,
and acknowledges the high cost of NGS.
However, the FAA disagrees with the
commenters’ requests. For passengercarrying airplanes, the cost per airplane
of providing a modification of the FQIS
that fully complies with the
airworthiness standards was estimated
by Boeing and their FQIS vendor
(Goodrich) prior to the issuance of the
NPRM to be comparable to the cost of
installing NGS. Based on that cost
estimate, Boeing proposed that they not
be required to develop a fully compliant
FQIS modification for passenger
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airplanes because it would not provide
significant savings to operators and NGS
would provide a greater safety benefit.
The FAA agreed.
The FAA’s understanding is that
Boeing’s current position is the same,
and that they do not plan to develop a
fully compliant FQIS modification for
passenger airplanes to address
paragraph (g) of this AD. However, if
service information is developed,
approved, and available in the future,
operators may request approval under
the provisions of paragraph (i) of this
AD to use approved service instructions
as an AMOC for the requirements of this
AD, or the FAA may approve the service
information as a global AMOC for this
AD.
Request To Clarify Intent of Different
Requirements in Paragraphs (g) and (h)
of the Proposed AD
Boeing asked that the FAA clarify the
intent of the differences between the
requirements in paragraphs (g) and (h)
of the proposed AD. Boeing stated that
it is unclear what change is expected for
compliance with paragraph (g) of the
proposed AD versus paragraph (h) of the
proposed AD. Boeing suggested that one
possibility is that paragraph (g) of the
proposed AD is intended to cover
development of transient suppression,
while paragraph (h) of the proposed AD
is intended to cover compliance via
FQIS wire separation and BITE checks.
The FAA agrees to clarify. Paragraph
(g) of this AD is intended to require, for
passenger airplanes that are subject to
this AD, a modification to the FQIS that
makes it fully compliant with 14 CFR
25.981(a), as amended by amendment
25–102. A fully compliant FQIS
modification might include wire
separation or transient suppression
devices, but due to the system design,
either option would likely require
changes to the FQIS processor.
Paragraph (h) of this AD is intended
to allow, as an optional method of
compliance for all-cargo airplanes only,
a change that isolates the center fuel
tank circuit wiring between the FQIS
processor and the fuel tanks from other
wiring that is connected to a sufficient
power source to create an ignition
source in the event of a hot short
between the wiring. Such a change
would not be fully compliant with the
airworthiness regulations (hence the
requirement to obtain a partial
exemption from 14 CFR 25.901(c) and
14 CFR 25.981(a) for any such design
change), but would provide a level of
risk reduction that the FAA considers
acceptable for all-cargo airplanes and
would significantly reduce the costs
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relative to a fully compliant
modification.
Request To Change Compliance Time
A4A/CAA and Thomson Airways
requested that the FAA extend the
compliance time for the modifications
specified in paragraphs (g) and (h)(2) of
the proposed AD to 72 months. A4A/
CAA stated that the compliance time
should match that of AD 2016–07–07
because the unsafe condition and
corrective actions are similar. A4A/CAA
stated that although service information
was not yet available, the compliance
time should align with major
maintenance schedules, but should be
not less than 72 months after service
information is available. Thomson
Airways noted that 72 months would
provide operators a better opportunity
to work within existing maintenance
program schedules.
Conversely, NATCA recommended
that the FAA reject requests for a
compliance time longer than 5 years as
proposed in the NPRM. Assuming final
rule issuance in 2016, NATCA
estimated that a 5-year compliance time
would result in required compliance by
2021–25 years after the TWA Flight 800
fuel tank explosion that led to the
requirements in SFAR 88, and 20 years
after issuance of SFAR 88.
The FAA agrees with Thomson
Airways and A4A/CAA’s request to
extend the compliance time, and
disagrees with NATCA’s request. The
FAA received similar requests to extend
the compliance time from several
commenters regarding the NPRMs for
the FQIS modification on other
airplanes. The FAA disagrees with
establishing a compliance time based on
issuance of any service information that
is not yet approved or available. The
FAA has determined that a 72-month
compliance time is appropriate and will
provide operators adequate time to
prepare for and perform the required
modifications without excessive
disruption of operations. The FAA has
determined that the requested moderate
increase in compliance time will
continue to provide an acceptable level
of safety. The FAA has changed
paragraphs (g) and (h)(2) of this AD
accordingly.
Request To Change Compliance Time
Relative to Receipt of Exemption
Boeing requested that the FAA revise
the compliance time for the proposed
AD to ‘‘60 months after an exemption
from [14 CFR 25.981(a)(3)] is FAAapproved.’’ Boeing suggested that it
would take 6 months to develop an
exemption petition and 6 months for the
FAA to approve that exemption. Boeing
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added that the FAA has previously
identified that the BITE checks
procedure and wire separation design
were not sufficient for compliance with
14 CFR 25.981(a)(3).
The FAA disagrees with the
commenter’s request. An AD typically
does not include a compliance time that
is based on an optional action that an
operator or manufacturer might choose
to take. In addition, the FAA notes that
Boeing has already received exemptions
for the Model 747–400, 757, and 767
airplanes, and could quickly petition for
and obtain approval of a similar
exemption for the Model 737 airplanes
using an almost identical petition. The
FAA’s flow time to disposition such a
petition would be approximately 90
days, during which time Boeing could
still proceed with development of the
modification. In addition, as noted
above, the compliance time for
paragraph (h)(2) of this AD has been
extended to 72 months, giving
additional time for operators or
manufacturers to obtain an exemption.
Request To Extend Repetitive BITE
Check Interval
Boeing requested that paragraph (h)(1)
of the proposed AD be revised to extend
the repetitive check interval for the
BITE checks. Boeing requested that the
repetitive interval be extended to 750
flight hours to match the repetitive
intervals specified in the service
information for a related AD.
The FAA agrees for the reason
provided, and because 750 flight hours
better aligns with most operators’
maintenance programs. The FAA
intended to propose a 750 flight hour
interval, but inadvertently specified 650
flight hour intervals in the proposed
AD. The FAA has revised paragraph
(h)(1) of this AD to specify repetitive
intervals of 750 flight hours.
Request To Revise Costs of Compliance
Section To Account for Cargo
Conversions
A4A/CAA noted that the Costs of
Compliance section in the NPRM stated
all U.S.-registered airplanes are
currently operated as passenger
airplanes and that ‘‘because of the
requirement in 14 CFR 121.1117 to
install FRM on U.S. air-carrier passenger
airplanes by the end of 2017, it is likely
that no U.S. airplanes would actually be
affected by this proposed AD.’’ A4A/
CAA noted that 14 CFR 121.1117 does
not require FRM to be installed on allcargo airplanes. The commenter stated
that U.S.-registered Model 737–700 allcargo airplanes without FRM installed
will be operated by 2017. The FAA
infers that A4A/CAA is requesting that
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the Costs of Compliance section be
revised to reflect the number of all-cargo
U.S.-registered airplanes.
The FAA agrees that there are
currently U.S.-registered Model 737–700
all-cargo airplanes operating without
FRM installed. The FAA has revised the
Costs of Compliance section of this AD
to reflect these airplanes.
Request To Acknowledge Impacts on
Intrastate Aviation in Alaska
A4A/CAA stated that the proposed
AD will interrupt aviation
transportation to remote Alaskan
communities not serviced by other
modes of transportation, contrary to the
statement that the proposed AD ‘‘will
not affect intrastate aviation in Alaska.’’
A4A/CAA noted that, beginning in
2017, Model 737–700 airplanes in an
all-cargo configuration and without
FRM installed will provide
transportation to remote Alaskan
communities. A4A/CAA added that
these airplanes would be required to be
removed from service for an extended
time while accomplishing the proposed
modification, which the FAA estimates
would take 1,200 work-hours.
The FAA acknowledges that, since the
NPRM was issued, at least one major
operator began using converted Model
737–700 cargo airplanes for intrastate
flights in Alaska. The few remote
communities in Alaska that have
airports suitable for a Model 737–700
are unlikely to be served solely by
Model 737–700 airplanes. The FAA has
considered the potential for impact to
these communities due to Model 737–
700 airplanes being temporarily out of
service for the required modification
actions, and considers the safety
concern to outweigh those potential
impacts. This AD was developed with
regard to minimizing the economic
impact on operators to the extent
possible, consistent with the safety
objectives of this AD. In any event, the
Federal Aviation Regulations (14 CFR
part 39) require operators to correct an
unsafe condition identified on an
airplane to ensure operation of that
airplane in an airworthy condition. The
FAA has determined in this case that
the requirements are necessary and the
indirect costs would be outweighed by
the safety benefits of the AD. The FAA
considers the 72 month compliance
adequate time for operators to schedule
the required modifications without
excessive disruption of service to those
communities. However, if an operator
considers that a moderate delay in the
incorporation of the required
modification would significantly reduce
the impact on their operations or the
impact on service to a remote
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60055
community in Alaska while still
providing an acceptable level of safety,
that operator can use the procedures in
paragraph (i) of this AD to explain those
impacts and request approval of an
extension of the compliance time.
Request To Require Design Changes
From Manufacturers
NATCA recommended that the FAA
follow the agency’s compliance and
enforcement policy to require
manufacturers to develop the necessary
design changes soon enough to support
operators’ ability to comply with the
proposed requirements. NATCA noted
that SFAR 88 required manufacturers to
develop all design changes for unsafe
conditions identified by their SFAR 88
design reviews by December 2002, or
within an additional 18 months if the
FAA granted an extension.
The FAA acknowledges the
commenter’s concerns. However, any
enforcement action is outside the scope
of this rulemaking. The FAA has not
changed this final rule regarding this
issue.
Request To Clarify the Applicability
Duco Schiere stated the NPRM is not
clear about which configurations
(passenger/cargo, with/without NGS
installed) of Model 737 airplanes are
applicable to the AD. The FAA infers
the commenter is requesting the FAA
clarify the applicability.
The FAA agrees to clarify. This AD
applies to The Boeing Company Model
737–600, –700, –700C, –800, –900, and
–900ER series airplanes (including
passenger and cargo airplanes) except
for airplanes having configurations
identified in paragraphs (c)(1) and (2) of
this AD. Airplanes with an installed
NGS that meets the criteria specified in
paragraph (c)(1) of this AD are excluded
from this AD. Airplanes with an
installed IMM such as fuel tank
explosion suppression foam that meets
the criteria specified in paragraph (c)(2)
of this AD are also excluded from this
AD.
Clarification of BITE Check Compliance
Time
The FAA has revised paragraph (h)(1)
of this AD to clarify the compliance
time for the BITE check relative to the
requirement to record the fault codes.
The FAA recognized that operators
might interpret the proposed
requirements for alternative actions for
cargo airplanes as allowing additional
flights prior to performing the BITE
check after first recording the fault
codes. The FAA intended for operators
to perform the BITE check immediately
after recording the fault codes to address
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Federal Register / Vol. 85, No. 186 / Thursday, September 24, 2020 / Rules and Regulations
both the fault codes that exist prior to
performing the BITE check and any new
codes that are identified during the
BITE check.
Clarification of Costs of Compliance
The FAA had previously determined,
as specified in the NPRM, that the work
involved for the cargo airplane wire
separation modification would take 230
work-hours. Boeing has since provided
an updated estimate of 74 work-hours
for the alternative modification for cargo
airplanes. The FAA has revised the cost
estimate for the modification
accordingly in this final rule.
Conclusion
The FAA reviewed the relevant data,
considered the comments received, and
determined that air safety and the
public interest require adopting this
final rule with the changes described
previously and minor editorial changes.
The FAA has determined that these
minor changes:
• Are consistent with the intent that
was proposed in the NPRM for
addressing the unsafe condition; and
• Do not add any additional burden
upon the public than was already
proposed in the NPRM.
The FAA also determined that these
changes will not increase the economic
burden on any operator or increase the
scope of this final rule.
Costs of Compliance
There are approximately 1,393 U.S.registered Model 737–600, –700, –700C,
–800, –900, and –900ER series airplanes
in service. Several of those airplanes are
currently operated as cargo airplanes.
Beginning with line number 2620,
however, Boeing has delivered airplanes
with FRM/NGS installed. The FAA
estimates that 831 affected airplanes on
the U.S. Register were delivered without
FRM installed, but the agency does not
know the number of airplanes that have
had FRM installed post-production.
Because of the requirement in 14 CFR
121.1117 to install FRM on U.S. aircarrier passenger airplanes by the end of
2017, it is likely that no U.S. passenger
airplanes would actually be affected by
this AD. However, U.S.-registered cargo
airplanes may be affected by this AD.
For any affected airplane, the FAA
estimates the following costs to comply
with this AD:
ESTIMATED COSTS: REQUIRED ACTIONS
Action
Labor cost
Parts cost
Modification ..............................................
1,200 work-hours × $85 per hour =
$102,000.
Cost per product
$200,000
$302,000.
ESTIMATED COSTS: ALTERNATIVE ACTIONS
Action
Labor cost
BITE check ..............................................
1 work-hour × $85 per hour = $85 per
check.
74 work-hours × $85 per hour = $6,290
Wire separation .......................................
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.
The FAA is 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
This AD will not have federalism
implications under Executive Order
13132. This AD will not have a
substantial direct effect on the States, on
the relationship between the national
VerDate Sep<11>2014
16:01 Sep 23, 2020
Jkt 250001
Parts cost
$0
10,000
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 that this AD:
(1) Is not a ‘‘significant regulatory
action’’ under Executive Order 12866,
(2) Will not affect intrastate aviation
in Alaska, and
(3) 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.
Adoption of the Amendment
Accordingly, under the authority
delegated to me by the Administrator,
the FAA amends 14 CFR part 39 as
follows:
PART 39—AIRWORTHINESS
DIRECTIVES
1. The authority citation for part 39
continues to read as follows:
■
PO 00000
Frm 00010
Fmt 4700
Sfmt 4700
Cost per product
$85 per check (4 checks per year, $340
per year).
16,290.
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):
■
2020–18–13 The Boeing Company:
Amendment 39–21234; Docket No.
FAA–2016–6139; Product Identifier
2015–NM–061–AD.
(a) Effective Date
This AD is effective October 29, 2020.
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company
Model 737–600, –700, –700C, –800, –900,
and –900ER series airplanes, certificated in
any category, excluding airplanes identified
in paragraphs (c)(1) and (2) of this AD.
(1) Airplanes equipped with a flammability
reduction means (FRM) approved by the FAA
as compliant with the fuel tank flammability
reduction (FTFR) requirements of 14 CFR
25.981(b) or 26.33(c)(1).
(2) Airplanes equipped with an ignition
mitigation means (IMM) approved by the
FAA as compliant with the FTFR
requirements of 14 CFR 25.981(c) or
26.33(c)(2).
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Federal Register / Vol. 85, No. 186 / Thursday, September 24, 2020 / Rules and Regulations
(d) Subject
Air Transport Association (ATA) of
America Code 28, Fuel.
(e) Unsafe Condition
This AD was prompted by the FAA’s
analysis of the Model 737 fuel system
reviews conducted by the manufacturer. The
FAA is issuing this AD to prevent ignition
sources inside the center fuel tank, which, in
combination with flammable fuel vapors,
could result in a fuel tank explosion and
consequent loss of the airplane.
(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 fuel quantity
indicating system (FQIS) to prevent
development of an ignition source inside the
center fuel tank due to electrical fault
conditions, using a method approved in
accordance with the procedures specified in
paragraph (i) of this AD.
(h) Alternative Actions for Cargo Airplanes
For airplanes used exclusively for cargo
operations: As an alternative to the
requirements of paragraph (g) of this AD, do
the actions specified in paragraphs (h)(1) and
(2) of this AD, using methods approved in
accordance with the procedures specified in
paragraph (i) of this AD. To exercise this
alternative, operators must perform the first
inspection required under paragraph (h)(1) of
this AD within 6 months after the effective
date of this AD. To exercise this alternative
for airplanes returned to service after
conversion of the airplane from a passenger
configuration to an all-cargo configuration
more than 6 months after the effective date
of this AD, operators must perform the first
inspection required under paragraph (h)(1) of
this AD prior to further flight after the
conversion.
(1) Within 6 months after the effective date
of this AD, record the existing fault codes
stored in the FQIS processor and before
further flight thereafter do a BITE check
(check of built-in test equipment) of the
FQIS. If any nondispatchable fault code is
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 nondispatchable faults found, using
a method approved in accordance with the
procedures specified in paragraph (i) of this
AD. Repeat these actions thereafter at
intervals not to exceed 750 flight hours.
Modification as specified in paragraph (h)(2)
of this AD does not terminate the repetitive
BITE check requirement of this paragraph.
(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 tank wing spar
penetrations, including any circuits that
might pass through a main fuel tank, from
other airplane wiring that is not intrinsically
safe, using methods approved in accordance
with the procedures specified in paragraph
(i) of this AD.
VerDate Sep<11>2014
16:01 Sep 23, 2020
Jkt 250001
(i) Alternative Methods of Compliance
(AMOCs)
(1) The Manager, Seattle ACO Branch,
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
certification office, send it to the attention of
the person identified in paragraph (j) of this
AD. Information may be emailed to: 9-ANMSeattle-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.
(3) An AMOC that provides an acceptable
level of safety may be used for any repair,
modification, or alteration required by this
AD if it is approved by The Boeing Company
Organization Designation Authorization
(ODA) that has been authorized by the
Manager, Seattle ACO Branch, FAA, to make
those findings. To be approved, the repair
method, modification deviation, or alteration
deviation must meet the certification basis of
the airplane, and the approval must
specifically refer to this AD.
(j) Related Information
For more information about this AD,
contact Jon Regimbal, Aerospace Engineer,
Propulsion Section, FAA, Seattle ACO
Branch, 2200 South 216th St., Des Moines,
WA 98198; phone and fax: 206–231–3557;
email: Jon.Regimbal@faa.gov.
(k) Material Incorporated by Reference
None.
Issued on August 26, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness
Division, Aircraft Certification Service.
[FR Doc. 2020–19809 Filed 9–23–20; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
[Docket No.: FAA–2020–0809]
14 CFR Parts 61, 63, 65 and 67
Settlement Policy for Legal
Enforcement Actions Involving Medical
Certificate-Related Fraud, Intentional
Falsification, Reproduction, or
Alteration
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Notification of enforcement
policy.
AGENCY:
The FAA is adopting a policy
for the prompt settlement of legal
enforcement actions against individuals
who have violated FAA regulations
SUMMARY:
PO 00000
Frm 00011
Fmt 4700
Sfmt 4700
60057
proscribing any: Fraudulent or
intentionally false statement on an
application for a medical certificate or
other document used to show
compliance with any requirement for a
medical certificate; reproduction of a
medical certificate for fraudulent
purposes; or alteration of a medical
certificate. The policy is expected to
afford eligible individuals who hold an
airman or ground instructor certificate
and who are the subject of such a legal
enforcement action the opportunity to
apply for a new airman or ground
instructor certificate sooner than in the
absence of this policy.
DATES: This notification of enforcement
policy is effective September 30, 2020.
FOR FURTHER INFORMATION CONTACT:
James Barry, Manager, Policy/Audit/
Evaluation, Enforcement Division,
AGC–300, Federal Aviation
Administration, 800 Independence
Avenue SW, Washington, DC 20591;
telephone (202) 267–8198; james.barry@
faa.gov; or Brandon Goldberg, Attorney,
Enforcement Division, AGC–300,
Federal Aviation Administration, 1701
Columbia Ave., College Park, GA 30337;
telephone (404) 305–5230;
brandon.goldberg@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
Under longstanding FAA policy, the
revocation of airman, ground instructor,
and medical certificates, and the
withdrawal of all special issuances or
SODAs, is the appropriate sanction for
violations of 14 CFR 67.403(a)(1)
through (4).1 The period between the
discovery of an apparent violation of 14
CFR 67.403(a)(1) through (4) and, if
appropriate, the issuance of an order
revoking airman, medical, and ground
instructor certificates can be lengthy,
making the date on which an order of
revocation will be issued uncertain.
Investigative personnel compile an
1 Under 14 CFR 67.403(a)(1)–(4), a person is
prohibited from making or causing to be made: A
fraudulent or intentionally false statement on any
application for a medical certificate or on a request
for any Authorization for Special Issuance of a
Medical Certificate (Authorization) or Statement of
Demonstrated Ability (SODA); a fraudulent or
intentionally false entry in any logbook, record, or
report that is kept, made, or used to show
compliance with any requirement for any medical
certificate or for any Authorization or SODA; a
reproduction, for fraudulent purposes, of any
medical certificate; or an alteration of any medical
certificate. Under 14 CFR 67.403(b)(1)–(2), a
violation of 14 CFR 67.403(a)(1)–(4) is a basis for:
Suspending or revoking all airman, ground
instructor, and medical certificates and ratings held
by the violator and withdrawing all Authorizations
or SODA’s held by the violator. See also FAA Order
2150.3C, chap. 9, para. 8 (revocation is appropriate
for a violation of 14 CFR 67.403(a)(1)–(4) since such
a violation demonstrates a lack of qualification to
hold a certificate).
E:\FR\FM\24SER1.SGM
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Agencies
[Federal Register Volume 85, Number 186 (Thursday, September 24, 2020)]
[Rules and Regulations]
[Pages 60048-60057]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-19809]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2016-6139; Product Identifier 2015-NM-061-AD; Amendment
39-21234; AD 2020-18-13]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and
-900ER series airplanes. This AD was prompted by the FAA's analysis of
the Model 737 fuel system reviews conducted by the manufacturer. This
AD requires modifying the fuel quantity indicating system (FQIS) to
prevent development of an ignition source inside the center fuel tank
due to electrical fault conditions. This AD also provides alternative
actions for cargo airplanes.
[[Page 60049]]
The FAA is issuing this AD to address the unsafe condition on these
products.
DATES: This AD is effective October 29, 2020.
ADDRESSES:
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-2016-
6139; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, any comments received, and other information. The
address for Docket Operations is U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer,
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des
Moines, WA 98198; phone and fax: 206-231-3557; email:
[email protected].
SUPPLEMENTARY INFORMATION:
Discussion
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain The Boeing
Company Model 737-600, -700, -700C, -800, -900, and -900ER series
airplanes. The NPRM published in the Federal Register on May 3, 2016
(81 FR 26485). The NPRM was prompted by the FAA's analysis of the Model
737 fuel system reviews conducted by the manufacturer. The NPRM
proposed to require modifying the FQIS to prevent development of an
ignition source inside the center fuel tank due to electrical fault
conditions. The NPRM also proposed to provide alternative actions for
cargo airplanes.
The FAA is issuing this AD to address ignition sources inside the
center fuel tank, which, in combination with flammable fuel vapors,
could result in a fuel tank explosion and consequent loss of the
airplane.
Comments
The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.
Support for the NPRM
The Air Line Pilots Association, International (ALPA) and National
Air Traffic Controllers Association (NATCA) supported the intent of the
NPRM. Additional comments from NATCA are addressed below.
Request To Withdraw NPRM: Unjustified by Risk
Airlines for America and the Cargo Airline Association, in
consolidated comments (A4A/CAA), and KLM Royal Dutch Airlines (KLM)
requested that the FAA withdraw the NPRM. A4A/CAA cited comments
submitted by Boeing to Docket No. FAA-2012-0187 in which Boeing stated
that the risk is ``less than extremely improbable'' and that Boeing
does not believe that an unsafe condition exists. A4A/CAA noted that
they consider the Boeing comments to be applicable to the airplane
models in the NPRM. KLM stated that the NPRM does not clarify the
necessity of additional actions beyond current requirements. KLM added
that it understands that Boeing is not able to explain or substantiate
the rationale behind the NPRM.
The FAA disagrees with the commenters' request. The FAA notes that
Boeing's comments were addressed in the supplemental NPRM (SNPRM) for
Docket No. FAA 2012-0187 (80 FR 9400, February 23, 2015) in the comment
response for ``Request To Withdraw NPRM (77 FR 12506, March 1, 2012):
Unjustified by Risk.'' As explained in that comment response, in
addition to examining average risk and total fleet risk, the FAA
examines the individual flight risk on the worst reasonably anticipated
flights. In general, the FAA issues 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. The FAA
has determined that the current requirements, including airworthiness
limitations and critical design configuration control limitations
(CDCCLs) do not adequately address the unsafe condition identified in
this AD and therefore it is necessary to issue this final rule. The FAA
has not changed this AD regarding this issue.
Request To Withdraw NPRM: Probability Analysis Inconsistent With
Regulatory Requirements
A4A/CAA requested that the FAA withdraw the NPRM. A4A/CAA stated
that the assumption of a single failure regardless of probability is
inconsistent with 14 CFR part 25 regulatory requirements. A4A/CAA
referred to the phrase ``regardless of probability'' associated with
single failures. A4A/CAA acknowledged that the term is used with single
failures in FAA Advisory Circular (AC) 25.981-1C,\1\ ``Fuel Tank
Ignition Source Prevention Guidelines,'' but since that term does not
appear in 14 CFR 25.981(a)(3), the commenter considered its use
arbitrary, possibly introducing additional requirements not included in
that section. A4A/CAA stated that the ``worst reasonably anticipated
flight'' is a flight with a latent FQIS failure and a high-flammability
tank, and this ``latent plus one'' failure--regardless of probability
of a single failure--is not consistent with 14 CFR 25.981(a)(3).
---------------------------------------------------------------------------
\1\ https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25.981-1C.pdf.
---------------------------------------------------------------------------
The FAA disagrees with the commenter's request. The FAA notes that
the commenter's assertion about the intent of 14 CFR 25.981(a)(3) is
incorrect based on both the language of the rule and on the published
rulemaking documents. The absence of a probabilistic qualifier in both
the ``from each single failure'' clause and in the ``from each single
failure in combination with each latent failure not shown to be
extremely remote'' clause in 14 CFR 25.981(a)(3) in fact means just
that--there is no probabilistic qualifier intended by the regulation.
The intent for single failures in these two scenarios to be considered
regardless of probability of the single failure was explicitly stated
in the NPRM for 14 CFR 25.981, as amended by amendment 25-102 (66 FR
23085, May 7, 2001) (``amendment 25-102''). That NPRM stated, in
pertinent part, that it would also add a new paragraph (a)(3) to
require that a safety analysis be performed to demonstrate that the
presence of an ignition source in the fuel tank system could not result
from ``any single failure, from any single failure in combination with
any latent failure condition not shown to be extremely remote, or from
any combination of failures not shown to be extremely improbable.''
These new requirements would define three scenarios that must be
addressed in order to show compliance with the proposed paragraph
(a)(3). ``The first scenario is that any single failure, regardless of
the probability of occurrence of the failure, must not cause an
ignition source. The second scenario is that any single failure,
regardless of the probability occurrence, in combination with any
latent failure condition not shown to be at least
[[Page 60050]]
extremely remote (i.e., not shown to be extremely remote or extremely
improbable), must not cause an ignition source. The third scenario is
that any combination of failures not shown to be extremely improbable
must not cause an ignition source.''
The preamble to the final rule for amendment 25-102 made a nearly
identical statement, including the same uses of the phrase ``regardless
of probability.'' The FAA has determined that it is necessary to
proceed with issuance of this final rule as proposed. Further details
and a description of the FAA's risk assessment can be found in
responses to similar comments in a related SNPRM that addressed the
same unsafe condition for Model 757 airplanes, in Docket No. FAA-2012-
0187, and in the subsequently issued final rule, AD 2016-07-07,
amendment 39-18452 (81 FR 19472, April 5, 2016) (``AD 2016-07-07''). No
change to this AD was made in response to these comments.
Request To Withdraw NPRM: No New Data Since Fuel Tank Flammability
Reduction (FTFR) Rulemaking
A4A/CAA requested that the FAA withdraw the NPRM based on a lack of
new data since the issuance of the FTFR rule (73 FR 42444, July 21,
2008). A4A/CAA referred to the FTFR rule and decision to not require
flammability reductions means (FRM) for all-cargo airplanes, and the
FAA's intent to gather additional data and consideration of further
rulemaking if flammability of these airplanes is excessive. A4A/CAA
stated that since the FTFR rule, no additional data has been publicly
introduced that would support or justify the applicability of this
rulemaking to all-cargo aircraft. A4A/CAA also referred to the FAA's
response to comments in the preamble to the SNPRM for Docket No. FAA-
2012-0187, which documented the FAA's decision on applicability of FRM
and cost estimates. A4A/CAA stated that the FAA response was misleading
and not factual since manufacturers did not begin detailed designs to
address the proposed unsafe condition until after the FTFR rule was
published. A4A/CAA added that the FAA did not discuss other changes to
the FQIS system in the FTFR rule.
The FAA disagrees with the commenter's request. The FAA notes that
the FTFR rule and FQIS ADs are two different issues with separate FAA
actions. The intent of the FTFR rule was to provide an order of
magnitude reduction in the rate of fuel tank explosions for the
airplanes affected by that rule through adding a new airworthiness
standard for the flammability of fuel tanks. The FAA notes that the
FTFR rule was never intended to be a replacement for the issuance of
ADs to address identified unsafe conditions. An unsafe condition due to
the identified FQIS latent-plus-single failure issue in high-
flammability fuel tanks was determined to exist during the Special
Federal Aviation Regulation (SFAR) 88 AD Board held by the FAA in 2003
using the guidance in FAA Policy Memorandum ANM100-2003-112-15, ``SFAR
88--Mandatory Action Decision Criteria,'' dated February 25, 2003,\2\
for high-flammability fuel tanks, including the center fuel tank on
Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes.
That same issue was not considered to be an unsafe condition in low-
flammability wing fuel tanks based on that same policy memorandum. The
FAA has not changed this AD regarding this issue.
---------------------------------------------------------------------------
\2\ https://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgPolicy.nsf/0/dc94c3a46396950386256d5e006aed11/$FILE/Feb2503.pdf.
---------------------------------------------------------------------------
Request To Withdraw NPRM: Arbitrary and Inconsistent Wire Separation
Standards
A4A/CAA requested that the FAA withdraw the NPRM based on a lack of
consistent design standards for FQIS wire separation. A4A/CAA assumed
that the approved standard for the retrofit is a 2-inch wire separation
minimum, which the commenter considered arbitrary and inconsistently
applied. A4A/CAA reported that the amount of wiring capable of meeting
that separation standard varies widely among airplane models. A4A/CAA
also acknowledged that other separation methods were used in areas not
meeting the 2-inch wire separation requirement.
The FAA does not agree with the commenter's request. The degree of
physical isolation of FQIS wiring from other wiring, whether provided
by physical distance or barrier methods, that is necessary to eliminate
the potential for hot shorts due to wiring faults is dependent on the
materials used, the wire securing methods, and the possible types of
wiring faults. The FAA relied on the manufacturer to assess the details
of the design and to propose the appropriate isolation measures. While
2 inches of physical separation may appear to be an arbitrary number,
it was the distance proposed by the manufacturer as appropriate for
their design based on analysis of the design details. The FAA has not
changed this AD regarding this issue.
Request To Withdraw NPRM: NPRM Arbitrary and Inconsistently Applied
A4A/CAA requested that the FAA withdraw the NPRM. A4A/CAA noted
that airplanes with FRM are not included in the applicability, and the
NPRM would therefore not fully address the unsafe condition. A4A/CAA
added that the distinction between high- and low-flammability exposure
time fuel tanks as used in the NPRM is arbitrary. A4A/CAA stated that
an arbitrary differentiation of high- versus low-flammability as
decisional criteria for the need for corrective action does not take
into account the actual probability of the impact of the difference in
flammability on the potential of catastrophic failure. A4A/CAA also
stated that allowing the proposed alternative actions for cargo
airplanes does not fully address the unsafe condition in the NPRM. A4A/
CAA referenced the FAA's response to comments in AD 2016-07-07
regarding this issue. The commenter summarized numerical analysis
showing no significant difference in risk between high- and low-
flammability fuel tanks. A4A/CAA concluded that the FAA's risk analysis
is arbitrary and an unsafe condition does not exist.
The FAA disagrees with the assertion that the NPRM is arbitrary and
inconsistent. The NPRM follows defined policy in FAA Policy Memorandum
ANM100-2003-112-15, and consistently applies the policy to several
airplane models with similar unsafe conditions, similar to AD 2016-07-
07. The FAA defined the difference between low- and high-flammability
exposure time fuel tanks based on recommendations from the Aviation
Rulemaking Advisory Committee Fuel Tank Harmonization Working Group
(FTHWG). The preamble to the final rule for amendment 25-102, which
amended 14 CFR 25.981, defined this difference as based upon comparison
of ``the safety record of center wing fuel tanks that, in certain
airplanes, are heated by equipment located under the tank, and unheated
fuel tanks located in the wing.'' The FTHWG concluded that the safety
record of fuel tanks located in the wings was adequate and that if the
same level could be achieved in center wing fuel tanks, the overall
safety objective would be achieved.
In the response to comments in the preamble to the final rule for
AD 2016-07-07 referenced by the commenter, the FAA described why FRM or
alternative actions for cargo airplanes provide an acceptable level of
safety, even if they do not completely eliminate the non-compliance
with 14 CFR 25.981(a)(3).
[[Page 60051]]
The fuel tank explosion history for turbojet/turbofan powered
transport airplanes fueled with kerosene type fuels, outside of
maintenance activity, has consisted of explosions of tanks that (1) are
not conventional aluminum wing tanks and (2) spend a considerable
amount of their operating time empty. The service history of
conventional aluminum wing tanks has been acceptable. The intent of the
difference in decision criteria in FAA Policy Memorandum ANM100-2003-
112-15 was intended to give credit for this satisfactory service
experience, and to differentiate between tanks with a level of
flammability similar to that of a conventional wing tank and those with
a significantly higher level of flammability.
The numerical analysis provided by the commenter is inconsistent
with the fuel tank explosion service history. There are at least three
identifiable physics-based reasons for that inconsistency. First, low-
flammability tanks on most types of airplanes are main tanks that are
the last tanks used. During a large portion of their operating time,
the systems and structural features that have the potential to be
ignition sources in the event of a failure condition are covered with
liquid fuel, and an ignition source, if it occurs, is likely to be
submerged. When a potential ignition source in a main tank is
uncovered, it is likely to be later in the flight when the tank is cool
and no longer flammable. The commenter's analysis does not account for
this significant effect. Second, the numerical analysis used by the
commenter assumes that any given ignition source has a random
occurrence in time at the estimated probability, and that, in order for
an explosion to occur, that random occurrence of an ignition source
needs to coincide with the tank being in a flammable state. In fact,
many of the identified ignition threats do not simply occur briefly and
then go away. Instead, a fault occurs that, until it is discovered and
corrected, repeatedly creates an ignition source, and repeatedly tests
whether flammable conditions exist.
Third, the flammability of low-flammability fuel tanks is typically
dependent on weather, and a low-flammability fuel tank may operate for
months without ever becoming flammable. This is not true of most high-
flammability fuel tanks, which typically have significant on-airplane
heat sources driving their temperature. This factor can mean that, on
some airplanes, an in-tank latent failure can occur and, after some
period of time, be detected and corrected without the low-flammability
tank ever having flammable conditions. The numerical analysis provided
by the commenter does not account for these significant factors. The
difference in likelihood of a failure that results in repeated ignition
source events causing a tank explosion is not simply proportional to
difference in the fleet average flammability of the tank for the
reasons stated above. The FAA has not changed this AD regarding this
issue.
Request To Withdraw NPRM: Overestimate of Fleet Average Flammability
Exposure for All-Cargo Fleet in Alaska
A4A/CAA requested that the FAA withdraw the NPRM. The commenter
stated that the FAA did not properly analyze the fleet average
flammability for the center wing tank on Model 737-700 airplanes. The
commenter stated that the known U.S. registered 737-700 all-cargo fleet
without FRM installed will be operated almost solely in the state of
Alaska for the foreseeable future. A4A/CAA noted that the mean average
ambient temperature in Alaska is much lower than that used in the FAA's
analysis. The commenter added that the air conditioning packs in an
all-cargo configuration generate significantly less heat transfer to
the center wing tank during normal operations than during the normal
operations assumed by the FAA's analysis. A4A/CAA concluded that these
factors reduce the fleet average flammability exposure for the all-
cargo Model 737-700 airplanes to the level of the main wing tanks, and
therefore, the unsafe condition does not exist.
The FAA does not agree to withdraw the NPRM. More than 1,100 Model
737-700 airplanes have been produced. The FAA foresees that, as these
airplanes are replaced in passenger service by newer airplanes, a
significant portion of them will be converted to all-cargo service and
will eventually fly throughout the U.S. and the world. Multiple cargo-
conversion designs for these airplanes have been approved, and other
conversion designs are in the approval process. The FAA does not agree
to base its decision about whether an AD is necessary for these
airplanes on a flammability analysis based solely on the initial cargo
conversions currently being largely operated in Alaska.
The FAA also does not agree that a new analysis considering
operation of only the initial cargo-converted airplanes would result in
a determination that the center fuel tank of those airplanes has a
level of flammability comparable to a wing tank of conventional
aluminum construction, and that the center fuel tank on those airplanes
could therefore legitimately be classified as a low-flammability fuel
tank. In addition, the FAA considers the unsafe condition determination
described in the SNPRM for Docket No. FAA-2012-0187, in the response to
comments section under, ``Request To Withdraw NPRM (77 FR 12506, March
1, 2012): Unjustified by Risk,'' to be applicable to these Model 737
airplanes.
Request To Remove Certain Business Jets From the Applicability
AMES Continuing Airworthiness Management Organization (AMES CAMO)
requested that the proposed AD be revised to exclude Boeing Business
Jets operated under 14 CFR part 91. AMES CAMO noted that the proposed
AD excludes airplanes modified by the nitrogen generation system (NGS)
system, but the NGS is mandated only on commercial airplanes operating
under 14 CFR part 121. AMES CAMO suggested the proposed AD should only
apply to airplanes operating under 14 CFR part 121.
The FAA disagrees with the commenter's request. Policy Memorandum
ANM100-2003-112-15 is applicable to large transport airplanes except
those specifically excluded by the Special Federal Aviation Regulation
(SFAR) No. 88 regulation (in 14 CFR part 21). The FAA did not exclude
non-air-carrier large transport airplanes from the other ADs determined
to be necessary as a result of SFAR 88, and included non-air-carrier
large transport airplanes in the FRM retrofit requirements added to 14
CFR part 125 in 2008. The unsafe condition addressed by this AD is
applicable to Model 737 airplanes operated as business jets, except as
specified in paragraph (c) of this AD. The FAA has not changed this AD
regarding this issue.
Request To Require Cargo Airplane Option for All Airplanes
Boeing and All Nippon Airways (ANA) requested that the NPRM be
revised to make the alternative actions for cargo airplanes specified
in paragraph (h) of the proposed AD applicable to all airplanes. Boeing
asked that the FAA provide a technical justification why the actions in
paragraph (h) of the proposed AD apply only to cargo airplanes. ANA
asked that the actions in paragraph (h) of the proposed AD be allowed
for passenger airplanes not subject to the FTFR rule, suggesting this
would provide more choices regarding how to comply with the proposed
AD.
The FAA disagrees with the commenters' requests. As discussed in
the comment response in the SNPRM
[[Page 60052]]
for Docket No. FAA-2012-0187, under the heading ``Requests To Withdraw
NPRM (77 FR 12506, March 1, 2012) Based on Applicability'' the FAA does
not consider the alternative action for cargo airplanes allowed by this
AD to provide an adequate level of safety for passenger airplanes. The
FAA is willing 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 not
changed this AD regarding this issue.
Request To Exclude Certain Airplanes
United Airlines (UAL) noted that the FRM required by 14 CFR
121.1117 will have been installed on all affected airplanes in
passenger configuration by December 26, 2018. The FAA infers UAL is
requesting that the FAA revise the proposed AD to exclude airplanes
that are affected by 14 CFR 121.1117. In addition, UAL suggested that
the FAA either delete paragraph (g) of the proposed AD or make
paragraph (g) of the proposed AD applicable only to airplanes in a
cargo configuration that do not have an FRM installed and non-U.S.-
registered airplanes that do not have to comply with FRM requirements.
The FAA disagrees with the commenter's request. There are other
passenger-carrying airplanes operated under 14 CFR part 91 that are not
required to install FRM. (The requirement to install FRM on all
passenger-carrying airplanes operated by air carriers is in 14 CFR
121.1117.) The FAA notes that foreign air carriers may not have to
comply with that requirement or similar requirements of their own civil
aviation authority. The European Union Aviation Safety Agency (EASA),
for example, has chosen not to require FRM to be retrofitted to in-
service airplanes. This AD is intended to require any Model 737-600, -
700, -700C, -800, -900, and -900ER series passenger airplane that does
not have FRM, regardless of the rules under which it is operated, to
address the FQIS latent-plus-one unsafe condition with a corrective
action that fully complies with the FAA's airworthiness standards. This
requirement fulfills the FAA's International Civil Aviation
Organization to address unsafe conditions on all of the aircraft
manufactured by the state of design, not just those aircraft whose
operation is under the jurisdiction of the state of design. The FAA has
not changed this AD regarding this issue.
Request To Clarify Certification Basis for Modification Requirements
NATCA recommended that the FAA revise paragraph (g) of the proposed
AD to clearly state that the required FQIS design changes must comply
with the fail-safe requirements of 14 CFR 25.901(c), as amended by
amendment 25-46 (43 FR 50597, October 30, 1978); and 14 CFR 25.981(a)
and (b), as amended by amendment 25-102; NATCA added that these
provisions are required by SFAR 88.
The FAA does not agree to change paragraph (g) of this AD. While
the FAA agrees that modifications to comply with paragraph (g) of this
AD should be required to comply with the referenced regulations, that
requirement already exists in 14 CFR part 21. No change to this AD is
necessary.
Request To Address Unsafe Condition on All Fuel Tanks
NATCA recommended that the FAA require design changes that
eliminate unsafe FQIS failure conditions on all fuel tanks on the
affected models, regardless of fuel tank location or the percentage of
time the fuel tank is flammable. NATCA referred to four fuel tank
explosions in low-flammability exposure time fuel tanks identified by
the FAA during FTFR rulemaking. NATCA stated that neither FRM nor
alternative actions for cargo airplanes (e.g., BITE checks (checks of
built-in test equipment) followed by applicable repairs before further
flight and modification of the center fuel tank FQIS wiring within 60
months) would bring the airplane into full regulatory compliance. NATCA
added that the combination of failures described in the NPRM meets the
criteria for ``known combinations'' of failures that require corrective
action in FAA Policy Memorandum ANM100-2003-112-15.
The FAA disagrees with the commenter's request. The FAA has
determined that according to Policy Memorandum ANM100-2003-112-15, the
failure condition for the airplanes affected by this AD should not be
classified as a ``known combination.'' While the FQIS design
architecture is similar to that of the early Boeing Model 747
configuration that is suspected of contributing to the TWA Flight 800
fuel tank explosion, significant differences exist in the design of
FQIS components and wire installations between the affected Boeing
models and the early Model 747 airplanes such that the intent of the
``known combinations'' provision for low-flammability fuel tanks in the
policy memorandum is not applicable. Therefore, this AD affects only
the identified Boeing airplanes with high-flammability exposure time
fuel tanks, as specified in paragraph (c) of this AD. The FAA provided
a detailed response to similar comments in the preamble of the final
rule for AD 2016-07-07. The FAA has not changed this final rule
regarding this issue.
Request To Require Modification on All Production Airplanes
NATCA recommended that the FAA require designs that comply with 14
CFR 25.901(c) and 25.981(a)(3) on all newly produced transport
airplanes. NATCA stated that continuing to grant exemptions to 14 CFR
25.901(c), as amended by amendment 25-40 (42 FR 15042, March 17, 1977);
and 14 CFR 25.981(a)(3), as amended by amendment 25-102; has allowed
continued production of thousands of airplanes with this known unsafe
condition.
The FAA disagrees with the commenter's request. The recommendation
to require production airplanes to fully comply with 14 CFR 25.901(c)
and 14 CFR 25.981(a)(3) is outside the scope of this rulemaking. In
addition, the FAA has implemented requirements for all large transport
airplanes produced after September 2010 to include flammability
reduction methods for tanks that would otherwise be high-flammability
fuel tanks. Boeing incorporated this change into the Model 737 series
airplanes that are still in production and the FAA has excluded those
models from the applicability of this AD. The FAA has not changed this
final rule regarding this issue.
Request To State That an Exemption is Required
Boeing requested that paragraph (h) of the proposed AD be revised
to state that an exemption is required to accomplish the specified
actions. Boeing stated that the FAA has identified that the BITE
procedure and wire separation design changes specified in the proposed
AD are not sufficient for compliance to 14 CFR 25.981(a) at the FQIS
level. Boeing stated that an exemption is therefore needed prior to
approval of the related design change.
The FAA agrees to clarify. The BITE check is not a type design
change or alteration, so no exemption from the airworthiness standards
is required for that action. The design data approval of any partial
wire separation modification would require an exemption. That exemption
would be obtained by the party seeking approval of the alteration data,
and no further exemption would be required for the party using that
data
[[Page 60053]]
to alter an aircraft. Obtaining such an exemption would be part of the
certification process for such a change, so, the FAA does not find it
necessary to include such information in paragraph (h) of this AD. In
addition, some parties may choose to comply with the AD using a design
change that fully complies with the airworthiness standards. The FAA
also notes that the commenter appears to misunderstand why an exemption
is needed for the required modification. The exemption is needed
because, even with the modification, the FQIS does not comply with 14
CFR 25.901(c) and 14 CFR 25.981(a). The exemption does not authorize
evaluation of a partial system for compliance with the system level
requirement. The FAA has not changed this AD regarding this issue.
Request To Exclude Airplanes That Have Installed an Ignition Mitigation
Means (IMM) or Flammability Impact Mitigation Means (FIMM)
AerSale stated that the Costs of Compliance section of the NPRM
only cites the requirements in 14 CFR 121.1117 to install FRM, but 14
CFR 121.1117 paragraph (d)(1) states that IMM, FRM, or FIMM may be
installed. AerSale suggested that all IMM, FRM, or FIMM installations
with the approval of the FAA Oversight Office would meet the
requirements of 14 CFR 121.1117. The FAA infers AerSale is requesting
that the proposed AD be revised to exclude airplanes on which IMM or
FIMM has been installed.
The FAA partially agrees with the commenter's request. The FAA
agrees that IMM provides a level of risk reduction at least as great as
that provided by FRM. The FAA does not agree that airplanes should be
excluded from paragraph (c) of this AD based on the installation of
FIMM alone. FIMM is applicable to design changes only, and is intended
to ensure that, if a fuel tank design change would otherwise have
increased the flammability of a fuel tank, the associated FIMM would
ensure that the flammability of that tank is not increased by the
design change. Therefore, FIMM itself does not address the need for FRM
for the original tank design. The FAA has revised paragraph (c) of this
AD to clarify that airplanes with an IMM approved by the FAA as
compliant with certain regulations are excluded from this AD. This
revision includes adding paragraphs (c)(1) and (2) of this AD.
Request To Record Only Certain Codes
Boeing requested that paragraph (h)(1) of the proposed AD be
revised to only require corrective actions if a nondispatchable fault
code pertaining to the center wing tank is recorded (as opposed to any
nondispatchable fault code being recorded). Boeing stated that all FQIS
wire separation changes in the proposed AD are limited to the center
wing tank, therefore only built-in test equipment (BITE) check messages
pertaining to the center wing tank are applicable to the proposed AD.
In addition, Boeing stated that a final rule should be postponed until
the FAA develops a list of ``nondispatchable fault codes'' in
conjunction with Boeing.
The FAA agrees that the unsafe condition addressed by this AD is
limited to the center wing tank. However, the FAA does not agree that
the AD should be changed as proposed by Boeing. It is not clear to the
FAA whether there may be FQIS BITE fault codes that are not clearly
identified as related to the center wing tank but that may impact
center tank circuits. Therefore, the FAA has determined that all
nondispatchable fault codes recorded prior to the BITE check or as a
result of the BITE check required by paragraph (h)(1) of this AD must
be addressed. Operators or Boeing may request an alternative method of
compliance (AMOC) under the provisions of paragraph (i) of this AD if
they can provide sufficient data that a particular fault code does not
pertain to the unsafe condition addressed by this AD.
Regarding the requirement to record and address fault codes read
immediately prior to running the BITE check procedure, the FAA notes
that the normal Boeing procedure for performing an FQIS BITE check is
to first erase all of the existing fault codes, then perform the BITE
check and troubleshoot any resulting new fault codes. For this AD, the
FAA did not want any already stored fault codes to be potentially
ignored due to erasure at the first step because some of the failures
of concern can be intermittent. This AD therefore requires operators to
record the existing codes before doing the BITE check, then do the BITE
check and record the new codes that result from that BITE check, and
then do the appropriate troubleshooting and corrective action for both
sets of codes per the manufacturer's guidance. The FAA has not changed
this AD regarding this issue.
Finally, the FAA does not agree to delay the final rule while
Boeing proposes and obtains FAA agreement on a list of nondispatchable
fault codes. The FAA requested service information from Boeing in 2016
to support the option for all-cargo airplanes on all of the Boeing
models for which similar FQIS ADs were planned. Boeing chose at that
time to develop service information only for the Model 747-400, 757,
and 767 airplanes because at that time only those airplanes had
affected cargo configuration for which Boeing was the design approval
holder. The FAA agreed at that time to not require Boeing to develop a
BITE check service bulletin for the Model 737 airplanes because Boeing
had not yet developed a cargo conversion service bulletin or
supplemental type certificate (STC) for the Model 737 airplanes. The
FAA also considered that, because the BITE check instructions already
existed in the Model 737 AMM, a BITE check service bulletin could be
developed quickly at a later date if needed. In addition, the process
for obtaining FAA agreement on a list of nondispatchable fault codes
for the models Boeing chose to support took less than 30 days. If any
service information is developed to support compliance with paragraph
(h) of this AD it will be evaluated for approval using the AMOC process
specified in paragraph (i) of this AD.
Request To Clarify Required Modification
ANA and Thomson Airways requested that the FAA provide
clarification regarding how to accomplish the modification specified in
paragraph (g) of the proposed AD. ANA noted that paragraph (h) of the
proposed AD provides clear alternative actions for cargo airplanes. ANA
stated that it could not identify how to modify the FQIS in passenger
airplanes not subject to the FTFR rule. ANA noted that it contacted
Boeing for clarification and Boeing stated that the FRM (which Boeing
calls NGS) retrofit is the method of compliance for these airplanes.
ANA asked that the FAA either clarify how to modify the FQIS system or
accept an FRM retrofit as terminating action. Thomson Airways asked if
the intent of the proposed AD is to install an NGS on affected
airplanes. Thomson Airways also asked for clarification regarding the
FQIS modification, stating that the proposed AD does not provide detail
regarding modifying the FQIS itself, only the FQIS wiring.
The FAA agrees to clarify. As noted in paragraph (c) of this AD,
airplanes on which FRM or IMM that meets certain FAA airworthiness
standards is installed are excluded from this AD. Paragraph (g) of this
AD requires modification of the FQIS on passenger airplanes to prevent
development of an ignition source inside the center fuel tank due to
electrical fault conditions. The specifics of this modification may
vary as long as the modification addresses the unsafe condition
[[Page 60054]]
identified in this AD and the procedures specified in paragraph (i) of
this AD are used to approve the modification method. Operators may
choose to install an FRM or IMM that meets the criteria specified in
paragraph (c), which would then remove that airplane from the
applicability of this AD, negating the need to do the modification
specified in paragraph (g) of this AD. Otherwise, operators must obtain
an AMOC as specified in paragraph (i) of this AD and modify their
airplane accordingly. The FAA has not changed this AD regarding this
issue.
Request To Provide a Detailed Cost-Effective Method of Compliance
Korean Air Lines (KAL), KLM, AMES CAMO, and Duco Schiere requested
that the FAA provide a detailed and cost-effective method of compliance
for passenger airplanes. KAL, AMES CAMO, and Duco Schiere noted that
the proposed AD does not provide a clear means of compliance for the
modification, such as a Boeing service bulletin. AMES CAMO noted that
without a clear method of compliance, it is difficult to determine the
extent of the required work. KAL and KLM noted that the majority of
non-FAA operators are not required to retrofit the NGS system. KLM
stated that since 2008 the level of fuel tank safety has been improved
by the implementation of several costly SFAR 88 service bulletins,
implementation of airworthiness limitations into the maintenance
program and implementation of CDCCLs into maintenance documents. KLM
mentioned that the modification would require an airplane to be out of
service for a lengthy time. KLM added that the modification would add
weight to the airplane and require additional fuel usage. KAL and KLM
requested that the FAA encourage Boeing to develop an acceptable cost-
effective method of compliance that does not require installation of an
NGS.
The FAA agrees that the lack of service information for FQIS
modifications makes it difficult to assess the required work to modify
the FQIS, and acknowledges the high cost of NGS. However, the FAA
disagrees with the commenters' requests. For passenger-carrying
airplanes, the cost per airplane of providing a modification of the
FQIS that fully complies with the airworthiness standards was estimated
by Boeing and their FQIS vendor (Goodrich) prior to the issuance of the
NPRM to be comparable to the cost of installing NGS. Based on that cost
estimate, Boeing proposed that they not be required to develop a fully
compliant FQIS modification for passenger airplanes because it would
not provide significant savings to operators and NGS would provide a
greater safety benefit. The FAA agreed.
The FAA's understanding is that Boeing's current position is the
same, and that they do not plan to develop a fully compliant FQIS
modification for passenger airplanes to address paragraph (g) of this
AD. However, if service information is developed, approved, and
available in the future, operators may request approval under the
provisions of paragraph (i) of this AD to use approved service
instructions as an AMOC for the requirements of this AD, or the FAA may
approve the service information as a global AMOC for this AD.
Request To Clarify Intent of Different Requirements in Paragraphs (g)
and (h) of the Proposed AD
Boeing asked that the FAA clarify the intent of the differences
between the requirements in paragraphs (g) and (h) of the proposed AD.
Boeing stated that it is unclear what change is expected for compliance
with paragraph (g) of the proposed AD versus paragraph (h) of the
proposed AD. Boeing suggested that one possibility is that paragraph
(g) of the proposed AD is intended to cover development of transient
suppression, while paragraph (h) of the proposed AD is intended to
cover compliance via FQIS wire separation and BITE checks.
The FAA agrees to clarify. Paragraph (g) of this AD is intended to
require, for passenger airplanes that are subject to this AD, a
modification to the FQIS that makes it fully compliant with 14 CFR
25.981(a), as amended by amendment 25-102. A fully compliant FQIS
modification might include wire separation or transient suppression
devices, but due to the system design, either option would likely
require changes to the FQIS processor.
Paragraph (h) of this AD is intended to allow, as an optional
method of compliance for all-cargo airplanes only, a change that
isolates the center fuel tank circuit wiring between the FQIS processor
and the fuel tanks from other wiring that is connected to a sufficient
power source to create an ignition source in the event of a hot short
between the wiring. Such a change would not be fully compliant with the
airworthiness regulations (hence the requirement to obtain a partial
exemption from 14 CFR 25.901(c) and 14 CFR 25.981(a) for any such
design change), but would provide a level of risk reduction that the
FAA considers acceptable for all-cargo airplanes and would
significantly reduce the costs relative to a fully compliant
modification.
Request To Change Compliance Time
A4A/CAA and Thomson Airways requested that the FAA extend the
compliance time for the modifications specified in paragraphs (g) and
(h)(2) of the proposed AD to 72 months. A4A/CAA stated that the
compliance time should match that of AD 2016-07-07 because the unsafe
condition and corrective actions are similar. A4A/CAA stated that
although service information was not yet available, the compliance time
should align with major maintenance schedules, but should be not less
than 72 months after service information is available. Thomson Airways
noted that 72 months would provide operators a better opportunity to
work within existing maintenance program schedules.
Conversely, NATCA recommended that the FAA reject requests for a
compliance time longer than 5 years as proposed in the NPRM. Assuming
final rule issuance in 2016, NATCA estimated that a 5-year compliance
time would result in required compliance by 2021-25 years after the TWA
Flight 800 fuel tank explosion that led to the requirements in SFAR 88,
and 20 years after issuance of SFAR 88.
The FAA agrees with Thomson Airways and A4A/CAA's request to extend
the compliance time, and disagrees with NATCA's request. The FAA
received similar requests to extend the compliance time from several
commenters regarding the NPRMs for the FQIS modification on other
airplanes. The FAA disagrees with establishing a compliance time based
on issuance of any service information that is not yet approved or
available. The FAA has determined that a 72-month compliance time is
appropriate and will provide operators adequate time to prepare for and
perform the required modifications without excessive disruption of
operations. The FAA has determined that the requested moderate increase
in compliance time will continue to provide an acceptable level of
safety. The FAA has changed paragraphs (g) and (h)(2) of this AD
accordingly.
Request To Change Compliance Time Relative to Receipt of Exemption
Boeing requested that the FAA revise the compliance time for the
proposed AD to ``60 months after an exemption from [14 CFR
25.981(a)(3)] is FAA-approved.'' Boeing suggested that it would take 6
months to develop an exemption petition and 6 months for the FAA to
approve that exemption. Boeing
[[Page 60055]]
added that the FAA has previously identified that the BITE checks
procedure and wire separation design were not sufficient for compliance
with 14 CFR 25.981(a)(3).
The FAA disagrees with the commenter's request. An AD typically
does not include a compliance time that is based on an optional action
that an operator or manufacturer might choose to take. In addition, the
FAA notes that Boeing has already received exemptions for the Model
747-400, 757, and 767 airplanes, and could quickly petition for and
obtain approval of a similar exemption for the Model 737 airplanes
using an almost identical petition. The FAA's flow time to disposition
such a petition would be approximately 90 days, during which time
Boeing could still proceed with development of the modification. In
addition, as noted above, the compliance time for paragraph (h)(2) of
this AD has been extended to 72 months, giving additional time for
operators or manufacturers to obtain an exemption.
Request To Extend Repetitive BITE Check Interval
Boeing requested that paragraph (h)(1) of the proposed AD be
revised to extend the repetitive check interval for the BITE checks.
Boeing requested that the repetitive interval be extended to 750 flight
hours to match the repetitive intervals specified in the service
information for a related AD.
The FAA agrees for the reason provided, and because 750 flight
hours better aligns with most operators' maintenance programs. The FAA
intended to propose a 750 flight hour interval, but inadvertently
specified 650 flight hour intervals in the proposed AD. The FAA has
revised paragraph (h)(1) of this AD to specify repetitive intervals of
750 flight hours.
Request To Revise Costs of Compliance Section To Account for Cargo
Conversions
A4A/CAA noted that the Costs of Compliance section in the NPRM
stated all U.S.-registered airplanes are currently operated as
passenger airplanes and that ``because of the requirement in 14 CFR
121.1117 to install FRM on U.S. air-carrier passenger airplanes by the
end of 2017, it is likely that no U.S. airplanes would actually be
affected by this proposed AD.'' A4A/CAA noted that 14 CFR 121.1117 does
not require FRM to be installed on all-cargo airplanes. The commenter
stated that U.S.-registered Model 737-700 all-cargo airplanes without
FRM installed will be operated by 2017. The FAA infers that A4A/CAA is
requesting that the Costs of Compliance section be revised to reflect
the number of all-cargo U.S.-registered airplanes.
The FAA agrees that there are currently U.S.-registered Model 737-
700 all-cargo airplanes operating without FRM installed. The FAA has
revised the Costs of Compliance section of this AD to reflect these
airplanes.
Request To Acknowledge Impacts on Intrastate Aviation in Alaska
A4A/CAA stated that the proposed AD will interrupt aviation
transportation to remote Alaskan communities not serviced by other
modes of transportation, contrary to the statement that the proposed AD
``will not affect intrastate aviation in Alaska.'' A4A/CAA noted that,
beginning in 2017, Model 737-700 airplanes in an all-cargo
configuration and without FRM installed will provide transportation to
remote Alaskan communities. A4A/CAA added that these airplanes would be
required to be removed from service for an extended time while
accomplishing the proposed modification, which the FAA estimates would
take 1,200 work-hours.
The FAA acknowledges that, since the NPRM was issued, at least one
major operator began using converted Model 737-700 cargo airplanes for
intrastate flights in Alaska. The few remote communities in Alaska that
have airports suitable for a Model 737-700 are unlikely to be served
solely by Model 737-700 airplanes. The FAA has considered the potential
for impact to these communities due to Model 737-700 airplanes being
temporarily out of service for the required modification actions, and
considers the safety concern to outweigh those potential impacts. This
AD was developed with regard to minimizing the economic impact on
operators to the extent possible, consistent with the safety objectives
of this AD. In any event, the Federal Aviation Regulations (14 CFR part
39) require operators to correct an unsafe condition identified on an
airplane to ensure operation of that airplane in an airworthy
condition. The FAA has determined in this case that the requirements
are necessary and the indirect costs would be outweighed by the safety
benefits of the AD. The FAA considers the 72 month compliance adequate
time for operators to schedule the required modifications without
excessive disruption of service to those communities. However, if an
operator considers that a moderate delay in the incorporation of the
required modification would significantly reduce the impact on their
operations or the impact on service to a remote community in Alaska
while still providing an acceptable level of safety, that operator can
use the procedures in paragraph (i) of this AD to explain those impacts
and request approval of an extension of the compliance time.
Request To Require Design Changes From Manufacturers
NATCA recommended that the FAA follow the agency's compliance and
enforcement policy to require manufacturers to develop the necessary
design changes soon enough to support operators' ability to comply with
the proposed requirements. NATCA noted that SFAR 88 required
manufacturers to develop all design changes for unsafe conditions
identified by their SFAR 88 design reviews by December 2002, or within
an additional 18 months if the FAA granted an extension.
The FAA acknowledges the commenter's concerns. However, any
enforcement action is outside the scope of this rulemaking. The FAA has
not changed this final rule regarding this issue.
Request To Clarify the Applicability
Duco Schiere stated the NPRM is not clear about which
configurations (passenger/cargo, with/without NGS installed) of Model
737 airplanes are applicable to the AD. The FAA infers the commenter is
requesting the FAA clarify the applicability.
The FAA agrees to clarify. This AD applies to The Boeing Company
Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes
(including passenger and cargo airplanes) except for airplanes having
configurations identified in paragraphs (c)(1) and (2) of this AD.
Airplanes with an installed NGS that meets the criteria specified in
paragraph (c)(1) of this AD are excluded from this AD. Airplanes with
an installed IMM such as fuel tank explosion suppression foam that
meets the criteria specified in paragraph (c)(2) of this AD are also
excluded from this AD.
Clarification of BITE Check Compliance Time
The FAA has revised paragraph (h)(1) of this AD to clarify the
compliance time for the BITE check relative to the requirement to
record the fault codes. The FAA recognized that operators might
interpret the proposed requirements for alternative actions for cargo
airplanes as allowing additional flights prior to performing the BITE
check after first recording the fault codes. The FAA intended for
operators to perform the BITE check immediately after recording the
fault codes to address
[[Page 60056]]
both the fault codes that exist prior to performing the BITE check and
any new codes that are identified during the BITE check.
Clarification of Costs of Compliance
The FAA had previously determined, as specified in the NPRM, that
the work involved for the cargo airplane wire separation modification
would take 230 work-hours. Boeing has since provided an updated
estimate of 74 work-hours for the alternative modification for cargo
airplanes. The FAA has revised the cost estimate for the modification
accordingly in this final rule.
Conclusion
The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule with the changes described previously
and minor editorial changes. The FAA has determined that these minor
changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.
Costs of Compliance
There are approximately 1,393 U.S.-registered Model 737-600, -700,
-700C, -800, -900, and -900ER series airplanes in service. Several of
those airplanes are currently operated as cargo airplanes. Beginning
with line number 2620, however, Boeing has delivered airplanes with
FRM/NGS installed. The FAA estimates that 831 affected airplanes on the
U.S. Register were delivered without FRM installed, but the agency does
not know the number of airplanes that have had FRM installed post-
production. Because of the requirement in 14 CFR 121.1117 to install
FRM on U.S. air-carrier passenger airplanes by the end of 2017, it is
likely that no U.S. passenger airplanes would actually be affected by
this AD. However, U.S.-registered cargo airplanes may be affected by
this AD. For any affected airplane, the FAA estimates the following
costs to comply with this AD:
Estimated Costs: Required Actions
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Modification............................ 1,200 work-hours x $85 per $200,000 $302,000.
hour = $102,000.
----------------------------------------------------------------------------------------------------------------
Estimated Costs: Alternative Actions
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
BITE check.............................. 1 work-hour x $85 per hour $0 $85 per check (4 checks
= $85 per check. per year, $340 per year).
Wire separation......................... 74 work-hours x $85 per 10,000 16,290.
hour = $6,290.
----------------------------------------------------------------------------------------------------------------
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.
The FAA is 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
This AD will not have federalism implications under Executive Order
13132. This AD will 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 that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) 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.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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):
2020-18-13 The Boeing Company: Amendment 39-21234; Docket No. FAA-
2016-6139; Product Identifier 2015-NM-061-AD.
(a) Effective Date
This AD is effective October 29, 2020.
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, certificated in any
category, excluding airplanes identified in paragraphs (c)(1) and
(2) of this AD.
(1) Airplanes equipped with a flammability reduction means (FRM)
approved by the FAA as compliant with the fuel tank flammability
reduction (FTFR) requirements of 14 CFR 25.981(b) or 26.33(c)(1).
(2) Airplanes equipped with an ignition mitigation means (IMM)
approved by the FAA as compliant with the FTFR requirements of 14
CFR 25.981(c) or 26.33(c)(2).
[[Page 60057]]
(d) Subject
Air Transport Association (ATA) of America Code 28, Fuel.
(e) Unsafe Condition
This AD was prompted by the FAA's analysis of the Model 737 fuel
system reviews conducted by the manufacturer. The FAA is issuing
this AD to prevent ignition sources inside the center fuel tank,
which, in combination with flammable fuel vapors, could result in a
fuel tank explosion and consequent loss of the airplane.
(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
fuel quantity indicating system (FQIS) to prevent development of an
ignition source inside the center fuel tank due to electrical fault
conditions, using a method approved in accordance with the
procedures specified in paragraph (i) of this AD.
(h) Alternative Actions for Cargo Airplanes
For airplanes used exclusively for cargo operations: As an
alternative to the requirements of paragraph (g) of this AD, do the
actions specified in paragraphs (h)(1) and (2) of this AD, using
methods approved in accordance with the procedures specified in
paragraph (i) of this AD. To exercise this alternative, operators
must perform the first inspection required under paragraph (h)(1) of
this AD within 6 months after the effective date of this AD. To
exercise this alternative for airplanes returned to service after
conversion of the airplane from a passenger configuration to an all-
cargo configuration more than 6 months after the effective date of
this AD, operators must perform the first inspection required under
paragraph (h)(1) of this AD prior to further flight after the
conversion.
(1) Within 6 months after the effective date of this AD, record
the existing fault codes stored in the FQIS processor and before
further flight thereafter do a BITE check (check of built-in test
equipment) of the FQIS. If any nondispatchable fault code is
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 nondispatchable
faults found, using a method approved in accordance with the
procedures specified in paragraph (i) of this AD. Repeat these
actions thereafter at intervals not to exceed 750 flight hours.
Modification as specified in paragraph (h)(2) of this AD does not
terminate the repetitive BITE check requirement of this paragraph.
(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 tank wing spar penetrations, including any
circuits that might pass through a main fuel tank, from other
airplane wiring that is not intrinsically safe, using methods
approved in accordance with the procedures specified in paragraph
(i) of this AD.
(i) Alternative Methods of Compliance (AMOCs)
(1) The Manager, Seattle ACO Branch, 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 certification office, send it to the attention of the
person identified in paragraph (j) of this AD. Information may be
emailed to: [email protected].
(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.
(3) An AMOC that provides an acceptable level of safety may be
used for any repair, modification, or alteration required by this AD
if it is approved by The Boeing Company Organization Designation
Authorization (ODA) that has been authorized by the Manager, Seattle
ACO Branch, FAA, to make those findings. To be approved, the repair
method, modification deviation, or alteration deviation must meet
the certification basis of the airplane, and the approval must
specifically refer to this AD.
(j) Related Information
For more information about this AD, contact Jon Regimbal,
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch,
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3557; email: [email protected].
(k) Material Incorporated by Reference
None.
Issued on August 26, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification
Service.
[FR Doc. 2020-19809 Filed 9-23-20; 8:45 am]
BILLING CODE 4910-13-P