Airworthiness Directives; The Boeing Company Airplanes, 67837-67851 [2019-26736]
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Federal Register / Vol. 84, No. 239 / Thursday, December 12, 2019 / Rules and Regulations
of the local flight standards district office/
certificate holding district office.
(2) Contacting the Manufacturer: For any
requirement in this AD to obtain instructions
from a manufacturer, the instructions must
be accomplished using a method approved
by the Manager, International Section,
Transport Standards Branch, FAA; or EASA;
or Dassault Aviation’s EASA Design
Organization Approval (DOA). If approved by
the DOA, the approval must include the
DOA-authorized signature.
(j) Related Information
For more information about this AD,
contact Tom Rodriguez, Aerospace Engineer,
International Section, Transport Standards
Branch, FAA, 2200 South 216th St., Des
Moines, WA 98198; telephone and fax 206–
231–3226.
(k) Material Incorporated by Reference
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(1) The Director of the Federal Register
approved the incorporation by reference
(IBR) of the service information listed in this
paragraph under 5 U.S.C. 552(a) and 1 CFR
part 51.
(2) You must use this service information
as applicable to do the actions required by
this AD, unless this AD specifies otherwise.
(i) European Union Aviation Safety Agency
(EASA) AD 2019–0273, dated November 4,
2019.
(ii) [Reserved]
(3) For information about EASA AD 2019–
0273, contact the EASA, Konrad-AdenauerUfer 3, 50668 Cologne, Germany; telephone
+49 221 89990 6017; email ADs@
easa.europa.eu; Internet
www.easa.europa.eu. You may find this
EASA AD on the EASA website at https://
ad.easa.europa.eu.
(4) You may view this material at the FAA,
Transport Standards Branch, 2200 South
216th St., Des Moines, WA. For information
on the availability of this material at the
FAA, call 206–231–3195. This material may
be found in the AD docket on the internet at
https://www.regulations.gov by searching for
and locating Docket No. FAA–2019–0973.
(5) You may view this material that is
incorporated by reference at the National
Archives and Records Administration
(NARA). For information on the availability
of this material at NARA, email fedreg.legal@
nara.gov, or go to: https://www.archives.gov/
federal-register/cfr/ibr-locations.html.
Issued in Des Moines, Washington, on
November 21, 2019.
Dorr Anderson,
Acting Director, System Oversight Division,
Aircraft Certification Service.
[FR Doc. 2019–26704 Filed 12–11–19; 8:45 am]
BILLING CODE 4910–13–P
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2017–1024; Product
Identifier 2017–NM–065–AD; Amendment
39–19746; AD 2019–19–10]
RIN 2120–AA64
Airworthiness Directives; The Boeing
Company Airplanes
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
The FAA is adopting a new
airworthiness directive (AD) for all The
Boeing Company Model 737–300, –400,
–500, –600, –700, –700C, –800, –900,
and –900ER series airplanes; Model 757
series airplanes; Model 767 series
airplanes; Model 777 series airplanes;
and Model 787–8 and 787–9 airplanes.
This AD was prompted by reports of
fuel crossfeed valves failing to open
when activated during flight. This AD
requires, for certain airplanes, revising
the existing airplane flight manual
(AFM); and for certain other airplanes,
revising the existing minimum
equipment list (MEL) to do an
operational check of the fuel crossfeed
valve prior to each extended operations
(ETOPS) flight if one fuel crossfeed
valve (or the fuel balancing system on
Model 787 airplanes) is inoperative. The
FAA is issuing this AD to address the
unsafe condition on these products.
DATES: This AD is effective January 16,
2020.
ADDRESSES:
SUMMARY:
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–2017–
1024; 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,
the regulatory evaluation, 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:
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Discussion
The FAA issued a notice of proposed
rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would
apply to all The Boeing Company Model
737–300, –400, –500, –600, –700,
–700C, –800, –900, and –900ER series
airplanes; Model 757 series airplanes;
Model 767 series airplanes; Model 777
series airplanes; and Model 787–8 and
787–9 airplanes. The NPRM published
in the Federal Register on December 5,
2017 (82 FR 57383). The NPRM was
prompted by reports of fuel crossfeed
valves failing to open when activated
during flight. The NPRM proposed to
require, for certain airplanes, revising
the existing AFM; and for certain other
airplanes, revising the existing MEL to
do an operational check of the fuel
crossfeed valve prior to each ETOPS
flight if one fuel crossfeed valve (or the
fuel balancing system on Model 787
airplanes) is inoperative.
The FAA is issuing this AD to prevent
an airplane from being dispatched on an
ETOPS flight with a single fuel
crossfeed valve (due to design or due to
MEL dispatch of a dual crossfeed valve
equipped airplane with one crossfeed
valve inoperative) that cannot be
opened or a fuel balancing system that
cannot properly operate when activated.
This condition could cause the fuel in
the main tank associated with a failed
engine to be unavailable to the
remaining operative engine, potentially
resulting in a forced off-airport landing
due to exhaustion of the remaining
usable fuel and consequent loss of all
engine thrust.
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.
Request To Withdraw the NPRM
United Airlines (UAL) and Delta Air
Lines (DAL) asked that the NPRM be
withdrawn until corrective action is
proposed with an adequate level of
safety.
UAL stated that the FAA processes
leading to issuing the NPRM did not
include certain expected elements (e.g.,
risk analysis, adequate cost analysis
[which the FAA addresses in the
‘‘Request to Increase Cost Estimate’’
comment], and consideration for
airplanes equipped with aircraft health
monitoring (AHM) [which the FAA
addresses in the ‘‘Request to Exclude
Airplanes with AHM’’ comment]). UAL
added that it is not aware of an FAA risk
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analysis of a simultaneous engine
failure and a crossfeed valve failure
during an ETOPS flight in a critical fuel
location.
UAL conducted a risk analysis and
provided the following comments and
questions:
• The NPRM specified that the FAA
had received reports of fuel crossfeed
valves failing to open when activated
during flight, but provided no data.
• The NPRM provided no statistical
analysis of industry engine failure rates,
or of crossfeed valve failure rates. What
is the probability that an engine will fail
and a crossfeed valve will fail on the
same ETOPS flight in a fuel-critical
location?
• ETOPS-qualified aircraft engine
failure rates are extremely low. UAL
engine failure rates vary from 0.005 to
0.000, well below the 0.030 required for
ETOPS certification.
• Crossfeed valve failure rates are
extremely low (roughly 1 per 100,000
departures), and Boeing had indicated
that it did not regard the failure of
crossfeed valves as a potential reliability
issue.
DAL stated that a Boeing risk analysis
showed that an engine shutdown with
the inability to transfer fuel is
improbable (the FAA infers that the
commenter meant ‘‘extremely
improbable’’ as used in FAA risk
analysis policy) and that Boeing does
not consider this to be a safety issue.
DAL added that cycling the fuel
crossfeed valve prior to further flight, or
at any time, does not ensure that the
valve will work as intended at a later
point in flight. DAL concluded that the
proposed AD does not provide
corrective action that will improve the
safety of the airplane.
The FAA does not agree to withdraw
the NPRM. The FAA determined that
the unsafe condition of fuel crossfeed
valves failing to open or fuel balancing
systems failing to operate when
activated during flight must be
addressed. For transport airplanes, this
determination is based on several
criteria, and the failure to meet one or
more of the criteria could lead the FAA
to determine that corrective action is
warranted.
For each identified potential safety
issue on a transport airplane, the FAA
examines the risk on the worst
reasonably anticipated flights (flights
actually predicted to occur) to ensure
that each flight provides an acceptable
level of safety [identified as ‘‘individual
flight risk’’ in FAA risk analysis policy].
That acceptable level of safety consists
of three basic expectations:
• That each flight begins in a fail-safe
state (including consideration of latent
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failure conditions and allowed dispatch
states under the MEL), meaning that a
foreseeable single failure on any
anticipated flight should not have a
significant likelihood of causing a
catastrophic event.
• That each flight does not have a
numerical risk of a catastrophic event
due to the issue being examined that is
excessively (an order of magnitude or
more) greater than the risk of a
catastrophic event on an average
transport airplane.
• That safety features that were
prescriptively required due to lessons
learned from past incidents and
accidents are not excessively reduced in
their effectiveness or availability.
Failure to meet any of these three
criteria can lead to a determination that
an unsafe condition exists and AD
action is necessary, because the level of
safety on the affected flights does not
meet the FAA’s thresholds for an
acceptable level of safety on individual
flights.
For each identified potential safety
issue, the FAA also assesses the total
cumulative risk of an event occurring at
any time in the remaining life of the
fleet of affected airplanes (identified as
‘‘total fleet risk’’ in FAA risk analysis
policy). The FAA may determine that
corrective action is needed to limit total
fleet risk even when the assessed
individual flight risk does not violate
any of the three individual flight risk
criteria discussed above. Total fleet risk
is typically assessed by multiplying the
average probabilities of each of the
failures or other factors that contribute
to the occurrence of an event, the total
number of airplanes affected, the
average utilization of those airplanes,
and the average remaining life for those
airplanes. The FAA also considers the
number of occupants of an aircraft in
assessing fleet risk, and applies total
fleet risk guideline thresholds expressed
in terms of both aircraft accidents and
number of fatalities.
Either excessive individual flight risk
or excessive total fleet risk, or both, can
lead the FAA to determine that an
unsafe condition exists that requires
corrective action. The FAA does not use
or accept calculations of acceptable total
fleet risk, or acceptable average perflight-hour risk, as a justification for
taking no action on issues where an
excessive individual flight risk is
determined to exist on flights that are
anticipated to occur.
For this AD, the FAA identified that
flights of airplanes with a single
operative crossfeed valve (due to design
or due to MEL dispatch of a dual
crossfeed valve equipped airplane with
one crossfeed valve inoperative) are
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expected to occur with a pre-existing
undetected failure of that single
crossfeed valve (or of the fuel balancing
system on Boeing Model 787 airplanes).
On such a flight, if an engine shutdown
occurs during the fuel-critical ETOPS
portion of the flight, it can lead to fuel
exhaustion and a forced off-airport
landing. That fuel-critical portion of the
flight can be of significant duration. For
example, according to Boeing, the fuelcritical exposure window (during which
an engine failure without crossfeed
capability would lead to fuel exhaustion
prior to reaching a suitable airport
under the current 14 CFR part 121 fuel
reserve requirements) ranges from
approximately 1.8 to 2.3 hours in length
for flights between the West Coast of the
U.S. and Hawaii. For ETOPS missions
using greater-than-180-minute ETOPS
capability, the exposure can be
significantly greater.
While the average probability per
flight hour of a failure of the crossfeed
valve and an engine failure in cruise on
the same flight has been shown by
Boeing to be extremely improbable (on
the order of one event per billion flight
hours), the actual risk is not evenly
spread among flights at the average
level. Instead, most of that risk is
currently concentrated in the flights of
airplanes operating with a single
crossfeed valve due to design
configuration or MEL dispatch relief,
and on which that single crossfeed valve
is inoperative due to a latent failure. On
such flights, the estimated average
probability of an engine failure during
the cruise phase of flight is in the range
of one event per 100,000 to 1 million
flight hours (based on current industry
in-flight engine shutdown data),
depending on the engine/airplane
combination. In addition, engine
shutdowns can be caused by many
different single failures of engine or
airplane components, which means
those flights that begin with an already
inoperative crossfeed valve are not failsafe for an engine failure as required by
the airworthiness regulations and
expected by the public.
Based on the crossfeed valve actuator
failure rates supplied by the Boeing and
the current AFM requirements to check
the operation of the crossfeed valves in
the last hour of cruise on ETOPS flights,
the FAA estimates that well over 100
flights with inoperative crossfeed valves
will occur in the remaining life of the
affected fleet. Such flights do not
provide the level of safety that is
intended for ETOPS operations.
Checking the operation of the crossfeed
valve immediately prior to each ETOPS
flight will ensure that each flight begins
with a crossfeed valve that was recently
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verified to operate, and will minimize
the likelihood of a crossfeed valve
failing if engine crossfeed is required.
The FAA considers a check of the
crossfeed valve operation prior to each
ETOPS flight to be a significant
improvement in safety for the flights on
which the risk is actually concentrated,
thereby minimizing the chance that an
engine failure on one of those flights
will lead to a catastrophic fuel
exhaustion event. For the reasons
specified previously, the FAA is issuing
this final rule to address the identified
unsafe condition.
Request To Revise Airplanes Affected
by Certain Requirements
American Airlines generally
supported the NPRM, but asked that the
airplanes affected by paragraphs (h) and
(j) of the proposed AD be corrected.
American Airlines stated that
paragraphs (h) and (j) of the proposed
AD specify airplanes having line
numbers 1 through 616 inclusive and
618; however, the effectivity specified
in Boeing Service Bulletin 757–28–0029
for the corresponding actions is line
numbers 1 through 518 inclusive.
American Airlines added that airplanes
having line numbers above 518 had the
actions specified in the referenced
service information incorporated in
production.
The FAA agrees with the commenter’s
request for the reason provided.
Paragraphs (h) and (j) of this AD have
been changed accordingly.
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Effect of Winglets on Accomplishment
of the Proposed Actions
Aviation Partners Boeing (APB) stated
that the installation of winglets per
Supplemental Type Certificate (STC)
ST01219SE, ST00830SE, ST01518SE, or
ST01920SE does not affect the
accomplishment of the manufacturer’s
service instructions.
The FAA agrees that STC ST01219SE,
ST00830SE, ST01518SE, and
ST01920SE do not affect the
accomplishment of the manufacturer’s
service instructions. Therefore, the
installation of STC ST01219SE,
ST00830SE, ST01518SE, or ST01920SE
does not affect the ability to accomplish
the actions required by this AD. The AD
has not been changed in this regard.
Request To Increase Cost Estimate
UAL stated that the FAA did not
include adequate cost analysis and
stated the FAA should consider the
negative effects of daily activation of the
crossfeed valve on mean time between
failure (MTBF) rates, or the associated
cost of increased valve replacement
rates.
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The FAA infers that UAL is asking
that the cost estimate in the ‘‘Costs of
Compliance’’ section of this final rule be
increased to account for a decreased
MTBF for the crossfeed valve or
actuator. The FAA does not agree to
increase the estimated costs. The FAA
normally addresses only the direct cost
of a required action, and the agency has
not received any data from the
manufacturer or operators indicating
that actuating the crossfeed valve prior
to each ETOPS flight will significantly
increase the crossfeed valve failure and
replacement rate.
Relative to the effects of daily
activation of the crossfeed valve, a
significant decrease in MTBF will likely
not result from the actions in this AD,
for the following reasons:
• The various fuel system valves and
valve actuators are all of similar designs,
and some of those valves are cycled
once or more per flight. They are
designed to operate for many thousands
of cycles without failure.
• For airplanes equipped with a
single crossfeed valve, the existing AFM
requires operators to perform an
operational check of the crossfeed valve
in the last hour of cruise of every
ETOPS flight. This AD requires the
same check to be performed prior to
each ETOPS flight, and provides relief
from the existing requirement for a
valve operational check in the last hour
of cruise.
• For airplanes with dual crossfeed
valves or a fuel balancing system (for
Boeing Model 787 airplanes), this AD
requires a crossfeed valve operational
check only when the airplane is
operated under the MEL with a
crossfeed valve or fuel balance system
inoperative.
Therefore, this AD will not require a
significantly increased total number of
valve operational checks to be
performed; the AD just changes when
the check is performed. In light of these
factors, this AD has not been changed in
this regard.
Request To Exclude Airplanes With
AHM
UAL asked to revise the applicability
of the proposed AD to exclude airplanes
that have an AHM system capable of
reporting an impending crossfeed valve
failure before an actual service failure
occurs. UAL did not provide a reason
for its request, but the FAA infers that
the commenter considered that a system
that can detect an impending crossfeed
valve failure before an actual crossfeed
valve failure occurs, leading to a
precautionary crossfeed valve or
actuator replacement, would provide an
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67839
acceptable way to address the unsafe
condition.
The FAA does not agree with the
commenter’s request. The FAA is not
aware of any of the affected airplanes
having the capability to detect and
annunciate an impending crossfeed
valve failure. UAL did not identify a
specific airplane or installed system
feature that has that capability.
Operators may apply for an alternative
method of compliance (AMOC) in
accordance with paragraph (o) of this
AD, provided they can show that such
a system is available for installation on
an airplane and adequately addresses
the unsafe condition. The AD has not
been changed in this regard.
Request To Allow Alternative AFM
Approval
Southwest Airlines (SWA) contended
that use of the term ‘‘identical’’ in
paragraph (g)(2) of the proposed AD
would be unnecessarily restrictive and
could prevent operators from using
previously accepted formatting
standards and layout. SWA therefore
asked that paragraph (g)(2) of the
proposed AD be revised to add the
following statement: ‘‘Alternative
statements that meet the intent of the
following requirements may be used if
approved by an appropriate FAA POI.’’
SWA added that a similar principal
operations inspector (POI) allowance
was provided in AD 2011–18–03,
Amendment 39–16785 (76 FR 53317,
August 26, 2011).
The FAA does not agree with the
commenter’s request. The intent of this
AD is for the text of the general AFM
revision limitations and procedures to
be identical to that required by the AD;
however, formatting and layout can be
changed without an approved AMOC as
long as those changes do not change the
text of the statements. Operators may
apply for an AMOC in accordance with
paragraph (o) of this AD for any changes
to the text required by the AD. The AD
has not been changed in this regard.
Request To Include Certain Provisions
Required by Original Type Design
Boeing asked that paragraph (n) of the
proposed AD be changed to eliminate
certain existing requirements for
airplanes on which a last-hour-ofETOPS-flight crossfeed valve
operational check is in the AFM as part
of the type certificate approval. Boeing
stated that after publication of AD 88–
21–03 R1, Amendment 39–6077 (53 FR
46605, November 18, 1988) (‘‘AD 88–
21–03 R1’’), new airplane models with
a single crossfeed valve that were not
affected by the requirements in AD 88–
21–03 R1 had a similar requirement in
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the AFM as part of the airplane type
certificate.
The FAA does not agree with the
commenter’s request. The FAA approval
of the AFM change proposed by the
commenter would be considered an
approval of a voluntary change to a type
certificate. Such changes are required to
be approved under the process defined
in 14 CFR part 21 and are not
accomplished through an AD. Once the
operational check prior to each ETOPS
flight is incorporated into the existing
AFM or MEL as required by this AD, the
check required in the last hour of cruise
by the existing AFM could be
eliminated through a type certificate
design change approval. If Boeing or an
operator wants to obtain approval of a
revised AFM without the limitation
requiring the last-hour-of-ETOPS-flight
crossfeed valve operational check, the
request can be submitted for FAA
approval using the normal process for
obtaining approval of a revised AFM.
Therefore, the AD has not been changed
in this regard.
Request To Revise Headings for Certain
Figures
Boeing asked that the FAA expand the
headings for the AFM text in figure 3 to
paragraph (h)(1) of the proposed AD and
figure 5 to paragraph (i)(1) of the
proposed AD by adding ‘‘The following
is applicable prior to incorporation of
Boeing Service Bulletin 757–28–0029 or
production equivalent,’’ and ‘‘The
following is applicable prior to
incorporation of Boeing Service Bulletin
757–28–0034 or production equivalent,’’
respectively. Boeing stated that the
referenced service information and
production equivalent are closing
actions for the applicable AD.
The FAA partially agrees with the
commenter’s request. The FAA agrees to
change these headings, because an
operator could have a mixed fleet of
single- and dual-valve airplane
configurations operating under a single
AFM version, which should have
limitation language that is applicable
only to airplanes with a single crossfeed
valve. However, the FAA does not agree
with making the specific change by
referencing only service bulletins or
production equivalent configurations,
because while limitations with similar
language have been approved in the
past, the flight crew does not have
readily available information on the
service bulletins or production changes
that are installed. However, the crew
can readily identify whether the
airplane has one or two crossfeed valves
simply by looking at the overhead fuel
control panel, where either one or two
crossfeed valve switches are installed.
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Therefore, the referenced headings in
this AD have been changed to refer to
the crossfeed valve configuration rather
than the service bulletin number.
Request To Eliminate the Operational
Requirement in the MMEL
Boeing asked that the proposed
operational requirement for airplanes
with dual crossfeed valves operating on
the master minimum equipment list
(MMEL) be eliminated. Boeing stated
that after publication of AD 88–21–03,
which required operational checks of
the crossfeed valves in the last hour of
each ETOPS flight for airplanes
equipped with a single crossfeed valve,
the FAA approved the installation of a
second crossfeed valve as an AMOC for
that AD, without requiring any
crossfeed valve checks if the airplane is
operated with a crossfeed valve
inoperative under the MEL. Boeing
added that it is not necessary to now
mandate an operational check for an
airplane operating with a crossfeed
valve inoperative under the MEL.
Boeing stated that the fundamental
criterion for MMEL relief is that an
acceptable level of safety must be
maintained considering the next critical
single failure event in flight. Boeing also
stated that operation with a crossfeed
valve or transfer system inoperative
under the current MMEL requires
verification that the remaining crossfeed
valve is operative, and that in-flight
failure of the remaining crossfeed valve
during a subsequent flight would not
itself create an unsafe condition. Boeing
added that issuing an AD to require
operational checks for operation under
the MMEL is therefore redundant.
Boeing cited the preamble language
required by the FAA in MMEL Policy
Letter 34, Revision 4, dated August 15,
1997:
Experience has shown that with the
various levels of redundancy designed into
aircraft, operation of every system or
installed component may not be necessary
when the remaining operative equipment can
provide an acceptable level of safety.
Boeing stated that the addition of a
redundant crossfeed valve provides a
fault-tolerant configuration, which
experience has shown provides an
acceptable level of safety. Boeing
concluded that unless credit is given for
the redundant crossfeed valve without a
requirement for an operational check,
the redundant valve provides no added
safety benefit and therefore could be
eliminated.
The FAA does not agree with the
commenter’s request. When the FAA
determines that an existing MMEL relief
provision does not provide an
acceptable level of safety, the FAA may
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either eliminate or modify that relief
through AD action. In this case, the FAA
determined that an operational check of
the crossfeed valve, prior to each ETOPS
flight that takes place with a single
crossfeed valve, is necessary to prevent
dispatch of an ETOPS flight with no
ability to access all of the remaining fuel
in the event of an engine failure. The
FAA has further determined that flights
without the ability to access all of the
remaining fuel would not provide an
acceptable level of safety, because a
single engine failure during the critical
portion of the cruise phase could result
in a forced offairport landing due to
inadequate usable fuel available to the
operative engine. This check is
necessary when an airplane equipped
with a dual crossfeed valve is
dispatched under the MMEL with one
crossfeed valve inoperative or with the
fuel balancing system inoperative, for
the same reason that the crossfeed valve
operational check is required prior to
each ETOPS flight on an airplane with
a single crossfeed valve.
The citation from MMEL Policy Letter
34 is from the standardized language
required by that policy letter to be
included in the preamble of an MMEL.
It is simply an introductory statement
indicating that redundant systems may
allow for dispatch with certain
equipment inoperative in some cases. It
is not intended to restrict the conditions
or limitations that the FAA may place
on a particular MMEL relief provision.
The failure of a crossfeed valve in a
manner that will prevent it from
actuating is typically detected only
through subsequent attempted actuation
of the crossfeed valve for fuel balancing,
or for crossfeed in the event of an engine
failure. Therefore, the failure of the
crossfeed valve is likely to remain
undiscovered from the time of the
failure until the next attempt at
actuation. This latency period may
occur during several flights in some
operational situations, such as
movement of an individual airplane to
an ETOPS route when that airplane has
previously been operated on nonETOPS routes. That operational
situation and the associated latency
period increases the likelihood that the
crossfeed valve on that airplane will fail
when the next attempt is made to
actuate the crossfeed valve. An
operational check of the crossfeed valve
immediately prior to each ETOPS flight
(the flights where the ability to open the
crossfeed valve may be critical) is a
practical measure to minimize the
likelihood that the crossfeed valve will
fail to open if needed, and to ensure that
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the flight is started with an operative
crossfeed valve.
The addition of a second crossfeed
valve provides redundancy that the
FAA determined in the past was an
acceptable substitute for a preflight
operational check, and that also could
allow for dispatch with one crossfeed
valve inoperative. However, since that
time the FAA has determined that when
an airplane is operated with a crossfeed
valve (or a fuel balancing system) under
the MEL, it should be operated with the
same crossfeed valve operational check
requirement as an airplane with a single
crossfeed valve configuration, for the
same reason that the preflight
operational check is required for an
airplane with a single crossfeed valve
configuration. Therefore, the AD has not
been changed in this regard.
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Request To Correct Errors in Figure 10
Boeing, UAL, All Nippon Airways
(ANA), and Captain David Stewart
(Captain Stewart) asked that the
language specified in figure 10 to
paragraph (m) of the proposed AD be
corrected to reflect that the allowed
MMEL dispatch relief in that figure is
for the fuel balance system instead of
the crossfeed valve. UAL listed four
specific MMEL provisions (specified in
paragraphs (m)(1) through (4) of this
AD) that are for various inoperative
components or systems that cause the
fuel balance system to be inoperative.
Boeing and ANA stated that the figure
should be revised to reflect that if the
crossfeed valve fails to open, the FUEL
CROSSFEED advisory message will not
be displayed until 15 seconds after
crossfeed is selected ON. Captain
Stewart stated that the language in
figure 10 to paragraph (m) of the
proposed AD is erroneous and should
have stated ‘‘Before the next ETOPS
departure after the Fuel Balance Switch
is determined to be inoperative . . . .’’
The FAA agrees with the commenters’
requests for the reasons provided.
Figure 10 to paragraph (m) of this AD
has been revised to correct the errors
noted by the commenters.
Request To Revise the MMEL
Operational Check Requirements
United Airlines MEL Engineering
asked that the MMEL operational check
requirements in figure 4 to paragraph
(h)(2) of the proposed AD, figure 6 to
paragraph (i)(2) of the proposed AD,
figure 7 to paragraph (j) of the proposed
AD, and figure 8 to paragraph (k) of the
proposed AD be revised to allow the use
of either the ‘‘VALVE’’ light that is
integral to the crossfeed valve switch, or
the associated engine indication and
crew alerting system (EICAS) message
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for the preflight operational check. UAL
stated that if the ‘‘VALVE’’ light is
inoperative, it would be unable to
perform the check. UAL noted that
MMEL relief is provided for the
crossfeed valve lights.
The FAA does not agree with the
commenter’s request to perform the
check using the ‘‘FWD/AFT FUEL
CROSSFEED’’ EICAS message because
there are certain crossfeed valve
actuator failure modes that can cause
the crossfeed valve to remain closed
without the ‘‘FWD/AFT FUEL
CROSSFEED’’ EICAS message being
displayed. Short of directly observing
the valve actuator, monitoring the
VALVE light to verify that the crossfeed
valve actually transitioned from closed
to open is the only way to verify from
the flight deck that the crossfeed valve
transitioned to the open position. While
MMEL relief is provided for the VALVE
light, that relief is subject to the
provision that the crossfeed valve is
verified to operate correctly.
The FAA does agree to allow an
alternative procedure that is effective if
the ‘‘VALVE’’ light is inoperative,
because it is possible to perform an
operational check of the crossfeed valve
by directly observing the movement of
the actuator if the ‘‘VALVE’’ light is
inoperative. The FAA has revised the
referenced figures in this AD
accordingly.
Request To Revise Crossfeed Valve
Operational Check
The Air Line Pilots Association,
International (ALPA), Allied Pilots
Association (APA), and Captain Stewart
asked for revisions to the operational
checks specified in the proposed AD.
Captain Stewart asked that certain
crossfeed valve actions in the proposed
AD be changed to require one of the
following: (1) Performing the crossfeed
valve operational check in flight, prior
to entering the ETOPS segment of the
flight, and diverting the airplane to a
suitable airport if the check fails, or (2)
opening the crossfeed valve prior to
entry into the ETOPS segment, leaving
the crossfeed valve open throughout the
ETOPS segment, and diverting the
airplane to a suitable airport if the valve
fails to open. Captain Stewart pointed
out that operation with the crossfeed
valve open for the duration of the
ETOPS portion of the flight was proven
effective at a major airline.
ALPA, while supporting the inclusion
of an operational check prior to dispatch
of ETOPS flights, stated that since the
action in the proposed AD is not
directed at a specific crossfeed valve
failure mode, and is instead intended to
identify and minimize the exposure to
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any crossfeed valve failure mode, it is
important to check the crossfeed valve
in its normal operating environment
during flight. ALPA therefore requested
that the proposed AD be revised to
include an AFM requirement for
airplanes with only one crossfeed valve,
and a MEL requirement for airplanes
with two crossfeed valves, for an
operational check of the crossfeed valve
during cruise, prior to the entering
ETOPS airspace.
APA had no objection to the steps for
checking the crossfeed valve operation,
using the procedure recommended by
the original equipment manufacturer
(OEM). APA recommended checking the
crossfeed valve immediately prior to the
ETOPS segment of the flight where its
operation has the potential to be critical.
The FAA does not agree with the
commenters’ requests. Although the
agency agrees that operationally
checking the crossfeed valve
immediately prior to entering the
critical ETOPS portion of each ETOPS
flight would provide a greater reduction
in the risk that a crossfeed valve will fail
to open in the fuel-critical phase of
flight should an engine failure occur, it
would also significantly increase the
costs associated with each discovered
failure of a crossfeed valve. The cost of
an air turn-back or diversion is
significantly higher than the cost of a
delay for maintenance, and is likely to
be greater than the cost of a flight
cancellation. The FAA considered the
additional costs that would be incurred
by operators from an air turn-back or
diversion each time a crossfeed valve
fails its check, and also considered the
additional reduction in exposure to
latent crossfeed valve failures that
develop between the time of a preflight
check and the time of an ETOPS entry
check. As a result of these
considerations, the FAA determined
that the incremental reduction in
exposure to the development of a latent
crossfeed valve failure due to checking
the crossfeed valve in-flight prior to
entry into the critical ETOPS portion of
the flight, when the low probability of
an engine failure is also considered, did
not justify imposing those significant
additional operational costs and service
disruptions on affected operators.
Before the NPRM was published, the
FAA discussed with Boeing the value of
conducting the crossfeed valve
operational check during flight under
cold soak conditions (which are part of
the normal operating environment),
versus performing the check on the
ground. As a result of some of the
comments on the NPRM, the agency
discussed this issue again with Boeing,
and placed a record of that discussion
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in the public rulemaking docket. Boeing
stated that the valve actuator failure
modes identified by other commenters
that result in actuator failures only in
cold soak conditions have been
corrected in newer designs. Boeing
further stated that the previous valve
actuator configurations that had those
issues are no longer in service. Boeing
added that it had no reason to believe
that a check of the current in-service
crossfeed valves under cold, in-flight
conditions would detect failures that
would not be detected on the ground.
In addition, the FAA does not agree
with the request to require operation
with the crossfeed valve open
throughout the ETOPS segment of flight.
While operation in that configuration
would prevent the need to open the
crossfeed valve in the event of an engine
failure, there are other failure scenarios
(such as a large fuel leak or
contamination of one main tank) where
operating with the crossfeed valve open
compromises the intended isolation and
independence of the fuel system for
each engine. Also, differences in fuel
pump performance could cause the
need for repeated switching off and on
of fuel pumps to maintain balanced
main tanks. The FAA considers this
undesirable because a flight crew error
could put one or both engines on
suction feed, potentially causing engine
flameout. It would also add start/stop
cycles on the fuel pumps, which could
cause additional pump failures. Such a
procedure is not recommended or
approved by either Boeing or the FAA.
Finally, that procedure violates the
required fuel usage procedures in the
limitations section of the FAA-approved
AFMs for all of the affected airplane
models, which require the airplane to be
operated with the crossfeed valve closed
except when it is specifically required
to be open for crossfeeding to maintain
balanced main tanks or for a low fuel
condition. Therefore, that procedure
would also violate 14 CFR 91.9, which
requires operators to operate aircraft in
accordance with their applicable AFM
limitations, unless a revised AFM was
approved. In light of all these factors,
the AD has not been changed in this
regard.
Request To Change MMEL-Related
Requirements
Captain Stewart recommended that
the proposed AD be revised to require
an MMEL revision with clearly written
provisions that identify the appropriate
verification to confirm that no latent
faults exist. Captain Stewart added that
there is no benefit in mandating specific
(M) & (O) procedures in the proposed
AD, because it would cause an
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unnecessary administrative burden.
Captain Stewart concluded that MELs
published without the adequate (M) &
(O) procedures indicates a failure of the
MEL review/approval process at the
flight standards district office (FSDO) or
certificate management office (CMO)
level.
The FAA infers that the commenter is
requesting that the MEL entries for
operation with an inoperative crossfeed
valve or fuel balancing system (for
Model 787 airplanes) state the
requirement for and objectives of the
MEL maintenance and operational
requirements, rather than mandating
specific maintenance or operational
procedures. The FAA does not agree
with the commenter’s request. In this
case, there are various ways that the
operational or maintenance check can
be done, some of which would not
detect all of the possible crossfeed valve
failure modes. Therefore, the FAA has
determined that the agency should
maintain control over the operational
and maintenance check procedures
used. Operators may, however, apply for
an AMOC in accordance with paragraph
(o) of this AD, provided they can show
that their proposed alternative
operational or maintenance procedures
adequately address the unsafe
condition. The AD has not been
changed in this regard.
Request To Exempt Certain Airplanes
FedEx asked that the proposed AD be
revised to exclude airplanes that are not
used for ETOPS operations from the
proposed requirement to revise the
existing AFM and MEL. Specifically,
FedEx requested that paragraphs (h), (i),
(j), and (k) of the proposed AD be
revised to add ‘‘Airplanes that are not
used for ETOPS operations are exempt
from the requirements of this
paragraph.’’ FedEx stated that the
proposed AD does not allow for
exemption of affected fleets that are not
certified or utilized for ETOPS
operations. FedEx reported that its fleets
include the types of airplanes affected
by the proposed AD, but that only its
Model 777F airplanes are certified for
ETOPS operations.
The FAA does not agree with the
commenter’s request. The addition of
the language proposed by the
commenter is not sufficient to ensure
that the existing AFM and MEL will be
updated as required by this AD if there
is an operational change in the future.
However, operators may apply for an
AMOC in accordance with paragraph (o)
of this AD, provided they submit a
proposal that (1) describes how the
operator will ensure that future
introduction of ETOPS operations
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includes the required AFM and MEL
changes and (2) is supported by its FAA
POI. The AD has not been changed in
this regard.
Request To Clarify Instructions for
Operational Check
FedEx and Japan Airlines (JAL) asked
that the language in figure 8 to
paragraph (k) of the proposed AD be
revised to include instructions for a fuel
crossfeed valve operational check
including ‘‘steps on the ground prior to
engine start.’’ The commenters
requested that ‘‘prior to engine start’’ be
changed to ‘‘prior to each flight.’’ FedEx
stated that this language should be
clarified given that the intent of the
proposed AD is to prevent fuel in the
main tank associated with the failed
engine from being unavailable to the
remaining operative engine, potentially
resulting in a forced off-airport landing.
JAL stated that the time for performing
the operational check in the proposed
AD is more restrictive than that in the
MMEL. JAL added that since both are
the same action, that compliance time
should be the same.
The FAA acknowledges the
commenters’ concerns regarding
potential misunderstanding of when to
perform the operational check, and
agree that clarification is necessary. The
FAA infers that FedEx found that figure
8 to paragraph (k) of this AD was not
sufficiently clear that the operational
check is intended to be performed prior
to each flight. The FAA presumes that
FedEx’s concern is that an operator
might perform the operational check
only once prior to the first engine start
after placing the other inoperative
crossfeed valve on MEL relief, but not
prior to subsequent flights on the MEL.
The intent of the procedure is that an
operational check of the crossfeed valve
be performed, by maintenance
personnel or flightcrew, immediately
prior to each ETOPS flight, as was stated
in the ‘‘Proposed AD Requirements’’
section of the NPRM.
The FAA disagrees with using the
specific language proposed by FedEx
because its language would not alleviate
the confusion about the intent of the
requirement, and might be interpreted
as allowing the check to be performed
at any time prior to flight, as opposed
to immediately prior to each flight.
Although the comment from FedEx
requested a change to figure 8 to
paragraph (k) of this AD, which
provides the required MEL revision for
the Model 767, the FAA is satisfied that
the MEL language in figure 7 to
paragraph (j) of this AD, figure 8 to
paragraph (k) of this AD, figure 9 to
paragraph (l) of this AD, and figure 10
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to paragraph (m) of this AD is clear with
respect to the intended timing of
performing the crossfeed valve
operational check.
The general intent of operational
procedures in the existing MEL is that
they are associated with each flight
conducted with the inoperative
equipment. However, the comments
provided caused the agency to
reconsider whether the corresponding
language in the AFM revisions required
for airplanes equipped with single
crossfeed valves are sufficiently clear
regarding the intended timing for the
check. In light of this, figure 1 to
paragraph (g)(1) of this AD, figure 3 to
paragraph (h)(1) of this AD, and figure
5 to paragraph (i)(1) of this AD of this
AD have been revised to clarify the
AFM limitations on airplanes equipped
with a single crossfeed valve. However,
the language in other figures, including
figure 8 to paragraph (k) of this AD,
have not been changed.
Request To Change Time for Performing
Operational Check
DAL asked that the time for
performing the operational check be
changed to the last hour of the cruise
flight, instead of prior to each ETOPS
flight. DAL stated that solder joint
cracks at the connectors and electronic
assembly could cause intermittent or
hard fault failure of the motor-operated
crossfeed valves (MOVs) that is difficult
to detect during the ground test prior to
each ETOPS flight. DAL added that a
cold soak test at the end of the cruise
flight will better detect intermittent
MOV failures than a test performed on
the ground.
The FAA does not agree with the
commenter’s request. At the FAA’s
request, Boeing examined the
commenter’s statements, and Boeing
provided comments. A record of the
phone conversation in which Boeing
provided its comments was placed in
the public rulemaking docket for this
AD. Boeing stated that the valve
actuator failure modes described by
DAL that tended to occur in cold
conditions were successfully addressed
by design improvements, and that the
valve actuator configurations that were
susceptible to failures that could only be
detected in cold conditions have been
replaced on operational aircraft and are
no longer in service. Boeing added that
its more recent failure data shows that
the timing of failures is random, and
that the ability to detect a failed
crossfeed valve is no longer significantly
impacted by environmental conditions
during the operational check.
As previously discussed, the FAA has
determined that the greatest practical
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reduction in risk during operation with
a single operational crossfeed valve
would be achieved by requiring the
operational check as close as possible to
the beginning of the fuel-critical ETOPS
portion of the flight. However, as noted,
the impact of requiring the operational
check in flight, just prior to entry into
the ETOPS portion of the flight, would
cause a significant number of air turnbacks and diversions at significant cost,
so the FAA, with agreement from
Boeing, proposed the check requirement
for immediately prior to each ETOPS
flight. Therefore, this AD has not been
changed in this regard.
Request To Reduce Compliance Time
ALPA asked that the compliance time
be reduced from 120 to 90 days. ALPA
stated that the proposed AD would not
require extensive, one-time maintenance
actions on affected airplanes, but only
revision of existing AFM and MEL
actions, thus the commenter
recommended a shorter compliance
time.
The FAA does not agree with the
commenter’s request. In conjunction
with Boeing, the FAA has determined
that the compliance time for each
airplane model will accommodate the
time necessary to accomplish the
actions required by this AD and
maintain an adequate level of safety. In
addition, the suggested compliance time
change would alter the requirements of
this AD, so additional rulemaking
would be required, ultimately delaying
issuance of the AD. The FAA finds that
delaying this action further is
inappropriate in light of the identified
unsafe condition. However, if additional
data are presented that would justify a
shorter compliance time, the FAA may
consider further rulemaking on this
issue. The AD has not been changed in
this regard.
Request To Add Airplanes to
Applicability
American Airlines asked that Model
737–7, –8, and –9 (MAX) airplanes be
added to the applicability of the
proposed AD. American Airlines stated
that the design on these airplanes is
similar to that of the Model 737 Classic
and Next Gen airplanes.
The FAA does not agree with the
request. Although the commenter is
correct about the similar design, this
unsafe condition was identified at the
time of certification of the 737 MAX
airplanes as a planned airworthiness
directive against the existing Model 737
airplanes. Therefore, Boeing included
the requirement for the operational
check of the crossfeed valve required by
this AD in the FAA-approved AFM for
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67843
the 737 MAX airplanes. The AD has not
been changed in this regard.
Engineering Oversight
Captain Stewart and APA stated that
it is an engineering oversight that new
production ETOPS airplanes are being
certificated with only one fuel crossfeed
valve installed.
The FAA acknowledges the
commenter’s concern about the risk
associated with two-engine ETOPS
airplanes that depend on a single active
component to allow the remaining
engine to access all of the remaining
fuel on board after an engine failure.
However, the allowance for such
designs was not an engineering
oversight, but a result of how the initial
120-minute ETOPS type-design
standards were developed with existing
airplanes in mind, of the later 180minute ETOPS type-design standards
being developed based on the 120minute standards, and of conscious
decision making by Boeing and the FAA
associated with AD 88–21–03 R1 (which
applies to certain Airbus Model A300
and A310–200 series airplanes, and
Boeing Model 737–200, 737–300, 757–
200, 767–200, and 767–300 series
airplanes) and certification of the Model
737–700 airplane. Discussion of the
potential need for improvements to
airworthiness standards is outside the
scope of the actions required by this AD.
Therefore, the AD has not been changed
in this regard.
Report of Incident
Commenter Amirul Ismail provided
what appears to be a pilot report of an
instance where an operational check of
the crossfeed valve on a Model 737–800
airplane resulted in the VALVE light
failing to extinguish. The incident
appears to be an indication-related fault
rather than a valve actuator failure. No
change to the final rule has been made.
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.
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Costs of Compliance
The FAA estimates that this AD
affects 3,252 airplanes of U.S. registry.
The FAA estimates the following costs
to comply with this AD:
ESTIMATED COSTS
Labor cost
AFM Revision (2,127 airplanes) ...............................
MEL Revision (1,125 airplanes) ................................
1 work-hour × $85 per hour = $85 ......
1 work-hour × $85 per hour = $85 ......
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.
This AD is issued in accordance with
authority delegated by the Executive
Director, Aircraft Certification Service,
as authorized by FAA Order 8000.51C.
In accordance with that order, issuance
of ADs is normally a function of the
Compliance and Airworthiness
Division, but during this transition
period, the Executive Director has
delegated the authority to issue ADs
applicable to transport category
airplanes and associated appliances to
the Director of the System Oversight
Division.
Regulatory Findings
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Parts
cost
Action
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,
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(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:
■
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):
■
2019–19–10 The Boeing Company:
Amendment 39–19746; Docket No.
FAA–2017–1024; Product Identifier
2017–NM–065–AD.
(a) Effective Date
This AD is effective January 16, 2020.
(b) Affected ADs
This AD affects AD 88–21–03 R1,
Amendment 39–6077 (53 FR 46605,
November 18, 1988) (‘‘AD 88–21–03 R1’’).
(c) Applicability
This AD applies to all The Boeing
Company airplanes, certificated in any
category, identified in paragraphs (c)(1)
through (5) of this AD.
(1) Model 737–300, –400, –500, –600, –700,
–700C, –800, –900, and –900ER series
airplanes.
(2) Model 757–200, –200PF, –200CB, and
–300 series airplanes.
(3) Model 767–200, –300, –300F, and
–400ER series airplanes.
(4) Model 777–200, –200LR, –300, –300ER,
and –777F series airplanes.
(5) Model 787–8 and 787–9 airplanes.
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Cost per
product
$0
0
$85
85
Cost on U.S.
operators
$180,795
95,625
(d) Subject
Air Transport Association (ATA) of
America Code 28; Fuel.
(e) Unsafe Condition
This AD was prompted by reports of fuel
crossfeed valves failing to open when
activated during flight. The FAA is issuing
this AD to prevent an airplane from being
dispatched on an extended operations
(ETOPS) flight with a single fuel crossfeed
valve (due to design or due to minimum
equipment list (MEL) dispatch of a dual
crossfeed valve equipped airplane with one
crossfeed valve inoperative) that cannot be
opened or a fuel balancing system that
cannot properly operate when activated. This
condition could cause the fuel in the main
tank associated with a failed engine to be
unavailable to the remaining operative
engine, potentially resulting in a forced off
airport landing due to exhaustion of the
remaining usable fuel and consequent loss of
all engine thrust.
(f) Compliance
Comply with this AD within the
compliance times specified, unless already
done.
(g) AFM Revisions for Model 737 Airplanes
Equipped With a Single Fuel Crossfeed
Valve
For airplanes identified in paragraph (c)(1)
of this AD: Within 120 days after the effective
date of this AD, do the actions specified in
paragraphs (g)(1) and (2) of this AD.
(1) Revise the ‘‘Extended Range
Operations’’ subsection of the ‘‘Fuel System
Limitations’’ section of the Section 1
Certificate Limitations of the existing
airplane flight manual (AFM) by
incorporating the information specified in
figure 1 to paragraph (g)(1) of this AD. This
may be done by inserting a copy of this AD
into the existing AFM. When a statement
identical to that in figure 1 to paragraph (g)(1)
of this AD has been included in the
‘‘Extended Range Operations’’ subsection of
the ‘‘Fuel System Limitations’’ section of the
Section 1 Certificate Limitations of the
general revisions of the existing AFM, the
general revisions may be inserted into the
existing AFM, and the copy of this AD may
be removed from the existing AFM.
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(2) Revise the ‘‘Extended Range
Operations’’ section of the Section 3 Normal
Procedures of the existing AFM by
incorporating the information specified in
figure 2 to paragraph (g)(2) of this AD. This
may be done by inserting a copy of this AD
into the existing AFM. When a statement
identical to that in figure 2 to paragraph (g)(2)
of this AD has been included in the
‘‘Extended Range Operations’’ section of
Section 3 Normal Procedures of the existing
AFM, the general revisions may be inserted
into the existing AFM, and the copy of this
AD may be removed from the existing AFM.
(h) AFM Revisions for Model 757 Airplanes
Equipped With a Single Fuel Crossfeed
Valve
this paragraph, if the actions specified in
Boeing Service Bulletin 757–28–0029 have
been done, the actions specified in this
paragraph are no longer required for that
airplane and the actions specified in
paragraph (j) of this AD must be done before
further flight after the actions specified in
Boeing Service Bulletin 757–28–0029 have
been performed.
(1) Revise the ‘‘Extended Range
Operations’’ section of the Section 1
Certificate Limitations of the existing AFM
by incorporating the information specified in
figure 3 to paragraph (h)(1). This may be
done by inserting a copy of this AD into the
existing AFM. When a statement identical to
that in figure 3 to paragraph (h)(1) of this AD
has been included in the ‘‘Extended Range
Operations’’ section of the Section 1
Certificate Limitations of the general
revisions of the existing AFM, the general
revisions may be inserted into the existing
AFM, and the copy of this AD may be
removed from the existing AFM.
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For airplanes identified in paragraph (c)(2)
of this AD having line numbers 1 through
518 inclusive, on which the actions specified
in Boeing Service Bulletin 757–28–0029
(second fuel crossfeed valve installation)
have not been done: Within 120 days after
the effective date of this AD, do the actions
specified in paragraphs (h)(1) and (2) of this
AD. For Model 757 airplanes identified in
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67846
Federal Register / Vol. 84, No. 239 / Thursday, December 12, 2019 / Rules and Regulations
(2) Revise the ‘‘Extended Range
Operations’’ section of Section 3 Normal
Procedures of the existing AFM by
incorporating the information specified in
figure 4 to paragraph (h)(2) of this AD. This
may be done by inserting a copy of this AD
into the existing AFM. When a statement
identical to that in figure 4 to paragraph
(h)(2) of this AD has been included in the
‘‘Extended Range Operations’’ section of
Section 3 Normal Procedures of the existing
AFM, the general revisions may be inserted
into the existing AFM, and the copy of this
AD may be removed from the existing AFM.
(i) AFM Revisions for Model 767 Airplanes
Equipped With a Single Fuel Crossfeed
Valve
paragraphs (i)(1) and (2) of this AD. For
airplanes on which the actions specified in
Boeing Service Bulletin 767–28–0034 have
been done, the actions specified in this
paragraph are no longer required for that
airplane and the actions specified in
paragraph (k) of this AD must be done before
further flight.
(1) Revise the ‘‘Extended Range
Operations’’ section of the Section 1
Certificate Limitations of the existing AFM
by incorporating the information specified in
figure 5 to paragraph (i)(1) of this AD. This
may be done by inserting a copy of this AD
into the existing AFM. When a statement
identical to that in figure 5 to paragraph (i)(1)
of this AD has been included in the
‘‘Extended Range Operations’’ section of the
Section 1 Certificate Limitations of the
general revisions of the existing AFM, the
general revisions may be inserted into the
existing AFM, and the copy of this AD may
be removed from the existing AFM.
ER12DE19.003
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For airplanes identified in paragraph (c)(3)
of this AD having line numbers 1 through
430 inclusive on which the actions specified
in Boeing Service Bulletin 767–28–0034
(second fuel crossfeed valve installation)
have not been done as of the effective date
of this AD: Within 120 days after the effective
date of this AD, do the actions specified in
Federal Register / Vol. 84, No. 239 / Thursday, December 12, 2019 / Rules and Regulations
(2) Revise the ‘‘Extended Range
Operations’’ section of Section 3.1 Normal
Procedures of the existing AFM by
incorporating the information specified in
figure 6 to paragraph (i)(2) of this AD. This
may be done by inserting a copy of this AD
into the existing AFM. When a statement
identical to that in figure 6 to paragraph (i)(2)
of this AD has been included in the
‘‘Extended Range Operations’’ section of
Section 3.1 Normal Procedures of the existing
AFM, the general revisions may be inserted
into the existing AFM, and the copy of this
AD may be removed from the existing AFM.
(j) MEL Revisions for Model 757 Airplanes
Equipped With Dual Fuel Crossfeed Valves
a second fuel crossfeed valve has been
installed, as specified in Boeing Service
Bulletin 757–28–0029: Within 120 days after
the effective date of this AD, revise the
operator’s existing FAA-approved MEL by
incorporating the information specified in
figure 7 to paragraph (j) of this AD as a
required operations procedure when
dispatching for ETOPS operation with an
inoperative fuel crossfeed valve. Specific
alternative MEL wording to accomplish the
actions specified in figure 7 to paragraph (j)
of this AD can be approved by the operator’s
principal operations inspector (POI).
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ER12DE19.004
ER12DE19.005
For airplanes identified in paragraph (c)(2)
of this AD having line numbers 519 and
subsequent; and for airplanes identified in
paragraph (c)(2) of this AD having line
numbers 1 through 518 inclusive, on which
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67847
(k) MEL Revisions for Model 767 Airplanes
Equipped With Dual Fuel Crossfeed Valves
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For airplanes identified in paragraph (c)(3)
of this AD having line numbers 431 and
subsequent; and for airplanes identified in
paragraph (c)(3) of this AD having line
numbers 1 through 430 inclusive on which
(l) MEL Revisions for Model 777 Airplanes
For airplanes identified in paragraph (c)(4)
of this AD: Within 120 days after the effective
date of this AD, revise the operator’s existing
FAA-approved MEL by incorporating the
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16:05 Dec 11, 2019
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a second fuel crossfeed valve has been
installed, as specified in Boeing Service
Bulletin 767–28–0034: Within 120 days after
the effective date of this AD, revise the
operator’s existing FAA-approved MEL by
incorporating the information specified in
figure 8 to paragraph (k) of this AD as a
required operations procedure when
dispatching for ETOPS operation with an
inoperative fuel crossfeed valve. Specific
alternative MEL wording to accomplish the
actions specified in figure 8 to paragraph (k)
of this AD can be approved by the operator’s
POI.
information specified in figure 9 to paragraph
(l) of this AD as a required operations
procedure when dispatching for ETOPS
operation with an inoperative fuel crossfeed
valve. Specific alternative MEL wording to
accomplish the actions specified in figure 9
to paragraph (l) of this AD can be approved
by the operator’s POI.
PO 00000
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ER12DE19.007
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ER12DE19.006
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Federal Register / Vol. 84, No. 239 / Thursday, December 12, 2019 / Rules and Regulations
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For airplanes identified in paragraph (c)(5)
of this AD: Within 120 days after the effective
date of this AD, revise the operator’s existing
FAA-approved MEL by incorporating the
information specified in figure 10 to
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16:05 Dec 11, 2019
Jkt 250001
paragraph (m) of this AD into the MEL
requirements for each of the inoperative
items specified in paragraphs (m)(1) through
(4) of this AD. Specific alternative MEL
wording to accomplish the actions specified
in figure 10 to paragraph (m) of this AD can
be approved by the operator’s POI.
PO 00000
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(1) 28–21–01–01 Pressure Refueling
System, Main Tank Inboard Refuel Valve.
(2) 28–22–06 Fuel Balance Switch.
(3) 28–26–01 Defuel/Isolation Valves.
(4) 28–41–01–01 Main Tank Fuel Quantity
Indication Systems.
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ER12DE19.008
(m) MEL Revisions for Model 787 Airplanes
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(n) AD 88–21–03 R1 AFM Limitation
Removal
After the applicable AFM limitations
specified in paragraphs (g)(1), (h)(1), and
(i)(1) of this AD are incorporated into an
airplane’s existing AFM, operators may
remove the AFM limitation required by AD
88–21–03 R1, for that airplane.
(o) 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
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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 (p) 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
PO 00000
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Fmt 4700
Sfmt 4700
(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.
(p) 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.
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Federal Register / Vol. 84, No. 239 / Thursday, December 12, 2019 / Rules and Regulations
(q) Material Incorporated by Reference
None.
Issued in Des Moines, Washington, on
October 3, 2019.
Michael Kaszycki,
Acting Director, System Oversight Division,
Aircraft Certification Service.
[FR Doc. 2019–26736 Filed 12–11–19; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA–2019–0494; Product
Identifier 2019–NM–051–AD; Amendment
39–19801; AD 2019–23–07]
RIN 2120–AA64
Airworthiness Directives; The Boeing
Company Airplanes
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
Discussion
The FAA is adopting a new
airworthiness directive (AD) for certain
The Boeing Company Model 787–8,
787–9, and 787–10 airplanes. This AD
was prompted by reports that the nose
landing gear (NLG) retracted on the
ground, with weight on the airplane’s
wheels, due to the incorrect installation
of an NLG downlock pin in the apex pin
inner bore of the NLG lock link
assembly. This AD requires installing an
insert to prevent installation of the pin
in the incorrect location. The FAA is
issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective January 16,
2020.
The Director of the Federal Register
approved the incorporation by reference
of a certain publication listed in this AD
as of January 16, 2020.
ADDRESSES: For service information
identified in this final rule, contact
Boeing Commercial Airplanes,
Attention: Contractual & Data Services
(C&DS), 2600 Westminster Blvd., MC
110–SK57, Seal Beach, CA 90740–5600;
telephone 562–797–1717; internet
https://www.myboeingfleet.com. You
may view this service information at the
FAA, Transport Standards Branch, 2200
South 216th St., Des Moines, WA. For
information on the availability of this
material at the FAA, call 206–231–3195.
It is also available on the internet at
https://www.regulations.gov by
searching for and locating Docket No.
FAA–2019–0494.
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SUMMARY:
VerDate Sep<11>2014
16:05 Dec 11, 2019
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–2019–
0494; 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,
the regulatory evaluation, 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:
Allen Rauschendorfer, Aerospace
Engineer, Airframe Section, FAA,
Seattle ACO Branch, 2200 South 216th
St., Des Moines, WA 98198; phone and
fax: 206–231–3528; email:
allen.rauschendorfer@faa.gov.
SUPPLEMENTARY INFORMATION:
Jkt 250001
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 787–8, 787–9, and 787–10
airplanes. The NPRM published in the
Federal Register on July 23, 2019 (84 FR
35352). The NPRM was prompted by
reports that the NLG retracted on the
ground, with weight on the airplane’s
wheels, due to the incorrect installation
of an NLG downlock pin in the apex pin
inner bore of the NLG lock link
assembly. The NPRM proposed to
require installing an insert to prevent
installation of the pin in the incorrect
location.
The FAA is issuing this AD to address
the NLG downlock pin being incorrectly
installed in the apex pin inner bore of
the NLG lock link assembly, which
could result in the NLG retracting on the
ground, possibly causing serious
injuries to personnel and passengers
and substantial damage to 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.
Request To Revise Applicability of the
Proposed AD
American Airlines (AAL) requested
that the FAA revise the applicability of
the AD to specify the affected part
numbers of the NLG lock link assembly
rather than the affected airplanes
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67851
because the affected parts may be
swapped between airplanes. AAL noted
that paragraph A.2. of Boeing
Requirements Bulletin B787–81205–
SB320040–00 RB, Issue 001, dated
March 12, 2019, specifies to identify,
modify, and part mark the spares. AAL
suggested that once the apex bin inner
bore insert is installed in the NLG lock
link assembly in production, the NLG
lock link assembly part number should
also change. AAL requested that, should
the FAA not revise the applicability of
the proposed AD to affected part
numbers, the applicability of the
proposed AD be revised to include all
Model 787 airplanes rather than only
the airplanes specified in Boeing
Requirements Bulletin B787–81205–
SB320040–00 RB, Issue 001, dated
March 12, 2019. AAL asserted that the
unsafe condition applies to all
airplanes.
The FAA disagrees with the request to
revise the applicability of this AD. This
AD does not require operators to
identify, modify, or part mark their
spares. Paragraph (g) of this AD
specifies to accomplish the actions in
accordance with the Accomplishment
Instructions of Boeing Requirements
Bulletin B787–81205–SB320040–00 RB,
Issue 001, dated March 12, 2019, and
does not specify to accomplish actions
in accordance with paragraph A.2. of
Boeing Requirements Bulletin B787–
81205–SB320040–00 RB, Issue 001,
dated March 12, 2019. Therefore, the
FAA has determined that it is
appropriate for this AD to apply to
Boeing Model 787–8, 787–9, 787–10
airplanes, line numbers 6 through 848
inclusive, as specified in Boeing
Requirements Bulletin B787–81205–
SB320040–00 RB, Issue 001, dated
March 12, 2019. Only these airplanes
need to have the apex bin inner bore
insert installed in order to address the
identified unsafe condition.
Regarding AAL’s request to revise the
applicability to all Model 787 airplanes,
Boeing will incorporate the apex pin
inner bore insert as part of the airplane
type design at line number 849 and
subsequent. At that time, the NLG lock
link assembly will change part numbers,
and the airplane type design will be
changed as a result. If an operator
installs an NLG lock link assembly of a
different part number than what is
defined as airplane type design, then the
airplane would be out of compliance.
Consequently, all airplanes will be
required to have the apex pin inner bore
insert installed in the NLG lock link
assembly. No changes have been made
to the applicability of this AD.
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Agencies
[Federal Register Volume 84, Number 239 (Thursday, December 12, 2019)]
[Rules and Regulations]
[Pages 67837-67851]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-26736]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2017-1024; Product Identifier 2017-NM-065-AD; Amendment
39-19746; AD 2019-19-10]
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 all
The Boeing Company Model 737-300, -400, -500, -600, -700, -700C, -800,
-900, and -900ER series airplanes; Model 757 series airplanes; Model
767 series airplanes; Model 777 series airplanes; and Model 787-8 and
787-9 airplanes. This AD was prompted by reports of fuel crossfeed
valves failing to open when activated during flight. This AD requires,
for certain airplanes, revising the existing airplane flight manual
(AFM); and for certain other airplanes, revising the existing minimum
equipment list (MEL) to do an operational check of the fuel crossfeed
valve prior to each extended operations (ETOPS) flight if one fuel
crossfeed valve (or the fuel balancing system on Model 787 airplanes)
is inoperative. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective January 16, 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-2017-
1024; 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, the regulatory evaluation, 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 all The Boeing Company
Model 737-300, -400, -500, -600, -700, -700C, -800, -900, and -900ER
series airplanes; Model 757 series airplanes; Model 767 series
airplanes; Model 777 series airplanes; and Model 787-8 and 787-9
airplanes. The NPRM published in the Federal Register on December 5,
2017 (82 FR 57383). The NPRM was prompted by reports of fuel crossfeed
valves failing to open when activated during flight. The NPRM proposed
to require, for certain airplanes, revising the existing AFM; and for
certain other airplanes, revising the existing MEL to do an operational
check of the fuel crossfeed valve prior to each ETOPS flight if one
fuel crossfeed valve (or the fuel balancing system on Model 787
airplanes) is inoperative.
The FAA is issuing this AD to prevent an airplane from being
dispatched on an ETOPS flight with a single fuel crossfeed valve (due
to design or due to MEL dispatch of a dual crossfeed valve equipped
airplane with one crossfeed valve inoperative) that cannot be opened or
a fuel balancing system that cannot properly operate when activated.
This condition could cause the fuel in the main tank associated with a
failed engine to be unavailable to the remaining operative engine,
potentially resulting in a forced off-airport landing due to exhaustion
of the remaining usable fuel and consequent loss of all engine thrust.
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.
Request To Withdraw the NPRM
United Airlines (UAL) and Delta Air Lines (DAL) asked that the NPRM
be withdrawn until corrective action is proposed with an adequate level
of safety.
UAL stated that the FAA processes leading to issuing the NPRM did
not include certain expected elements (e.g., risk analysis, adequate
cost analysis [which the FAA addresses in the ``Request to Increase
Cost Estimate'' comment], and consideration for airplanes equipped with
aircraft health monitoring (AHM) [which the FAA addresses in the
``Request to Exclude Airplanes with AHM'' comment]). UAL added that it
is not aware of an FAA risk
[[Page 67838]]
analysis of a simultaneous engine failure and a crossfeed valve failure
during an ETOPS flight in a critical fuel location.
UAL conducted a risk analysis and provided the following comments
and questions:
The NPRM specified that the FAA had received reports of
fuel crossfeed valves failing to open when activated during flight, but
provided no data.
The NPRM provided no statistical analysis of industry
engine failure rates, or of crossfeed valve failure rates. What is the
probability that an engine will fail and a crossfeed valve will fail on
the same ETOPS flight in a fuel-critical location?
ETOPS-qualified aircraft engine failure rates are
extremely low. UAL engine failure rates vary from 0.005 to 0.000, well
below the 0.030 required for ETOPS certification.
Crossfeed valve failure rates are extremely low (roughly 1
per 100,000 departures), and Boeing had indicated that it did not
regard the failure of crossfeed valves as a potential reliability
issue.
DAL stated that a Boeing risk analysis showed that an engine
shutdown with the inability to transfer fuel is improbable (the FAA
infers that the commenter meant ``extremely improbable'' as used in FAA
risk analysis policy) and that Boeing does not consider this to be a
safety issue. DAL added that cycling the fuel crossfeed valve prior to
further flight, or at any time, does not ensure that the valve will
work as intended at a later point in flight. DAL concluded that the
proposed AD does not provide corrective action that will improve the
safety of the airplane.
The FAA does not agree to withdraw the NPRM. The FAA determined
that the unsafe condition of fuel crossfeed valves failing to open or
fuel balancing systems failing to operate when activated during flight
must be addressed. For transport airplanes, this determination is based
on several criteria, and the failure to meet one or more of the
criteria could lead the FAA to determine that corrective action is
warranted.
For each identified potential safety issue on a transport airplane,
the FAA examines the risk on the worst reasonably anticipated flights
(flights actually predicted to occur) to ensure that each flight
provides an acceptable level of safety [identified as ``individual
flight risk'' in FAA risk analysis policy]. That acceptable level of
safety consists of three basic expectations:
That each flight begins in a fail-safe state (including
consideration of latent failure conditions and allowed dispatch states
under the MEL), meaning that a foreseeable single failure on any
anticipated flight should not have a significant likelihood of causing
a catastrophic event.
That each flight does not have a numerical risk of a
catastrophic event due to the issue being examined that is excessively
(an order of magnitude or more) greater than the risk of a catastrophic
event on an average transport airplane.
That safety features that were prescriptively required due
to lessons learned from past incidents and accidents are not
excessively reduced in their effectiveness or availability.
Failure to meet any of these three criteria can lead to a
determination that an unsafe condition exists and AD action is
necessary, because the level of safety on the affected flights does not
meet the FAA's thresholds for an acceptable level of safety on
individual flights.
For each identified potential safety issue, the FAA also assesses
the total cumulative risk of an event occurring at any time in the
remaining life of the fleet of affected airplanes (identified as
``total fleet risk'' in FAA risk analysis policy). The FAA may
determine that corrective action is needed to limit total fleet risk
even when the assessed individual flight risk does not violate any of
the three individual flight risk criteria discussed above. Total fleet
risk is typically assessed by multiplying the average probabilities of
each of the failures or other factors that contribute to the occurrence
of an event, the total number of airplanes affected, the average
utilization of those airplanes, and the average remaining life for
those airplanes. The FAA also considers the number of occupants of an
aircraft in assessing fleet risk, and applies total fleet risk
guideline thresholds expressed in terms of both aircraft accidents and
number of fatalities.
Either excessive individual flight risk or excessive total fleet
risk, or both, can lead the FAA to determine that an unsafe condition
exists that requires corrective action. The FAA does not use or accept
calculations of acceptable total fleet risk, or acceptable average per-
flight-hour risk, as a justification for taking no action on issues
where an excessive individual flight risk is determined to exist on
flights that are anticipated to occur.
For this AD, the FAA identified that flights of airplanes with a
single operative crossfeed valve (due to design or due to MEL dispatch
of a dual crossfeed valve equipped airplane with one crossfeed valve
inoperative) are expected to occur with a pre-existing undetected
failure of that single crossfeed valve (or of the fuel balancing system
on Boeing Model 787 airplanes). On such a flight, if an engine shutdown
occurs during the fuel-critical ETOPS portion of the flight, it can
lead to fuel exhaustion and a forced off-airport landing. That fuel-
critical portion of the flight can be of significant duration. For
example, according to Boeing, the fuel-critical exposure window (during
which an engine failure without crossfeed capability would lead to fuel
exhaustion prior to reaching a suitable airport under the current 14
CFR part 121 fuel reserve requirements) ranges from approximately 1.8
to 2.3 hours in length for flights between the West Coast of the U.S.
and Hawaii. For ETOPS missions using greater-than-180-minute ETOPS
capability, the exposure can be significantly greater.
While the average probability per flight hour of a failure of the
crossfeed valve and an engine failure in cruise on the same flight has
been shown by Boeing to be extremely improbable (on the order of one
event per billion flight hours), the actual risk is not evenly spread
among flights at the average level. Instead, most of that risk is
currently concentrated in the flights of airplanes operating with a
single crossfeed valve due to design configuration or MEL dispatch
relief, and on which that single crossfeed valve is inoperative due to
a latent failure. On such flights, the estimated average probability of
an engine failure during the cruise phase of flight is in the range of
one event per 100,000 to 1 million flight hours (based on current
industry in-flight engine shutdown data), depending on the engine/
airplane combination. In addition, engine shutdowns can be caused by
many different single failures of engine or airplane components, which
means those flights that begin with an already inoperative crossfeed
valve are not fail-safe for an engine failure as required by the
airworthiness regulations and expected by the public.
Based on the crossfeed valve actuator failure rates supplied by the
Boeing and the current AFM requirements to check the operation of the
crossfeed valves in the last hour of cruise on ETOPS flights, the FAA
estimates that well over 100 flights with inoperative crossfeed valves
will occur in the remaining life of the affected fleet. Such flights do
not provide the level of safety that is intended for ETOPS operations.
Checking the operation of the crossfeed valve immediately prior to each
ETOPS flight will ensure that each flight begins with a crossfeed valve
that was recently
[[Page 67839]]
verified to operate, and will minimize the likelihood of a crossfeed
valve failing if engine crossfeed is required. The FAA considers a
check of the crossfeed valve operation prior to each ETOPS flight to be
a significant improvement in safety for the flights on which the risk
is actually concentrated, thereby minimizing the chance that an engine
failure on one of those flights will lead to a catastrophic fuel
exhaustion event. For the reasons specified previously, the FAA is
issuing this final rule to address the identified unsafe condition.
Request To Revise Airplanes Affected by Certain Requirements
American Airlines generally supported the NPRM, but asked that the
airplanes affected by paragraphs (h) and (j) of the proposed AD be
corrected. American Airlines stated that paragraphs (h) and (j) of the
proposed AD specify airplanes having line numbers 1 through 616
inclusive and 618; however, the effectivity specified in Boeing Service
Bulletin 757-28-0029 for the corresponding actions is line numbers 1
through 518 inclusive. American Airlines added that airplanes having
line numbers above 518 had the actions specified in the referenced
service information incorporated in production.
The FAA agrees with the commenter's request for the reason
provided. Paragraphs (h) and (j) of this AD have been changed
accordingly.
Effect of Winglets on Accomplishment of the Proposed Actions
Aviation Partners Boeing (APB) stated that the installation of
winglets per Supplemental Type Certificate (STC) ST01219SE, ST00830SE,
ST01518SE, or ST01920SE does not affect the accomplishment of the
manufacturer's service instructions.
The FAA agrees that STC ST01219SE, ST00830SE, ST01518SE, and
ST01920SE do not affect the accomplishment of the manufacturer's
service instructions. Therefore, the installation of STC ST01219SE,
ST00830SE, ST01518SE, or ST01920SE does not affect the ability to
accomplish the actions required by this AD. The AD has not been changed
in this regard.
Request To Increase Cost Estimate
UAL stated that the FAA did not include adequate cost analysis and
stated the FAA should consider the negative effects of daily activation
of the crossfeed valve on mean time between failure (MTBF) rates, or
the associated cost of increased valve replacement rates.
The FAA infers that UAL is asking that the cost estimate in the
``Costs of Compliance'' section of this final rule be increased to
account for a decreased MTBF for the crossfeed valve or actuator. The
FAA does not agree to increase the estimated costs. The FAA normally
addresses only the direct cost of a required action, and the agency has
not received any data from the manufacturer or operators indicating
that actuating the crossfeed valve prior to each ETOPS flight will
significantly increase the crossfeed valve failure and replacement
rate.
Relative to the effects of daily activation of the crossfeed valve,
a significant decrease in MTBF will likely not result from the actions
in this AD, for the following reasons:
The various fuel system valves and valve actuators are all
of similar designs, and some of those valves are cycled once or more
per flight. They are designed to operate for many thousands of cycles
without failure.
For airplanes equipped with a single crossfeed valve, the
existing AFM requires operators to perform an operational check of the
crossfeed valve in the last hour of cruise of every ETOPS flight. This
AD requires the same check to be performed prior to each ETOPS flight,
and provides relief from the existing requirement for a valve
operational check in the last hour of cruise.
For airplanes with dual crossfeed valves or a fuel
balancing system (for Boeing Model 787 airplanes), this AD requires a
crossfeed valve operational check only when the airplane is operated
under the MEL with a crossfeed valve or fuel balance system
inoperative.
Therefore, this AD will not require a significantly increased total
number of valve operational checks to be performed; the AD just changes
when the check is performed. In light of these factors, this AD has not
been changed in this regard.
Request To Exclude Airplanes With AHM
UAL asked to revise the applicability of the proposed AD to exclude
airplanes that have an AHM system capable of reporting an impending
crossfeed valve failure before an actual service failure occurs. UAL
did not provide a reason for its request, but the FAA infers that the
commenter considered that a system that can detect an impending
crossfeed valve failure before an actual crossfeed valve failure
occurs, leading to a precautionary crossfeed valve or actuator
replacement, would provide an acceptable way to address the unsafe
condition.
The FAA does not agree with the commenter's request. The FAA is not
aware of any of the affected airplanes having the capability to detect
and annunciate an impending crossfeed valve failure. UAL did not
identify a specific airplane or installed system feature that has that
capability. Operators may apply for an alternative method of compliance
(AMOC) in accordance with paragraph (o) of this AD, provided they can
show that such a system is available for installation on an airplane
and adequately addresses the unsafe condition. The AD has not been
changed in this regard.
Request To Allow Alternative AFM Approval
Southwest Airlines (SWA) contended that use of the term
``identical'' in paragraph (g)(2) of the proposed AD would be
unnecessarily restrictive and could prevent operators from using
previously accepted formatting standards and layout. SWA therefore
asked that paragraph (g)(2) of the proposed AD be revised to add the
following statement: ``Alternative statements that meet the intent of
the following requirements may be used if approved by an appropriate
FAA POI.'' SWA added that a similar principal operations inspector
(POI) allowance was provided in AD 2011-18-03, Amendment 39-16785 (76
FR 53317, August 26, 2011).
The FAA does not agree with the commenter's request. The intent of
this AD is for the text of the general AFM revision limitations and
procedures to be identical to that required by the AD; however,
formatting and layout can be changed without an approved AMOC as long
as those changes do not change the text of the statements. Operators
may apply for an AMOC in accordance with paragraph (o) of this AD for
any changes to the text required by the AD. The AD has not been changed
in this regard.
Request To Include Certain Provisions Required by Original Type Design
Boeing asked that paragraph (n) of the proposed AD be changed to
eliminate certain existing requirements for airplanes on which a last-
hour-of-ETOPS-flight crossfeed valve operational check is in the AFM as
part of the type certificate approval. Boeing stated that after
publication of AD 88-21-03 R1, Amendment 39-6077 (53 FR 46605, November
18, 1988) (``AD 88-21-03 R1''), new airplane models with a single
crossfeed valve that were not affected by the requirements in AD 88-21-
03 R1 had a similar requirement in
[[Page 67840]]
the AFM as part of the airplane type certificate.
The FAA does not agree with the commenter's request. The FAA
approval of the AFM change proposed by the commenter would be
considered an approval of a voluntary change to a type certificate.
Such changes are required to be approved under the process defined in
14 CFR part 21 and are not accomplished through an AD. Once the
operational check prior to each ETOPS flight is incorporated into the
existing AFM or MEL as required by this AD, the check required in the
last hour of cruise by the existing AFM could be eliminated through a
type certificate design change approval. If Boeing or an operator wants
to obtain approval of a revised AFM without the limitation requiring
the last-hour-of-ETOPS-flight crossfeed valve operational check, the
request can be submitted for FAA approval using the normal process for
obtaining approval of a revised AFM. Therefore, the AD has not been
changed in this regard.
Request To Revise Headings for Certain Figures
Boeing asked that the FAA expand the headings for the AFM text in
figure 3 to paragraph (h)(1) of the proposed AD and figure 5 to
paragraph (i)(1) of the proposed AD by adding ``The following is
applicable prior to incorporation of Boeing Service Bulletin 757-28-
0029 or production equivalent,'' and ``The following is applicable
prior to incorporation of Boeing Service Bulletin 757-28-0034 or
production equivalent,'' respectively. Boeing stated that the
referenced service information and production equivalent are closing
actions for the applicable AD.
The FAA partially agrees with the commenter's request. The FAA
agrees to change these headings, because an operator could have a mixed
fleet of single- and dual-valve airplane configurations operating under
a single AFM version, which should have limitation language that is
applicable only to airplanes with a single crossfeed valve. However,
the FAA does not agree with making the specific change by referencing
only service bulletins or production equivalent configurations, because
while limitations with similar language have been approved in the past,
the flight crew does not have readily available information on the
service bulletins or production changes that are installed. However,
the crew can readily identify whether the airplane has one or two
crossfeed valves simply by looking at the overhead fuel control panel,
where either one or two crossfeed valve switches are installed.
Therefore, the referenced headings in this AD have been changed to
refer to the crossfeed valve configuration rather than the service
bulletin number.
Request To Eliminate the Operational Requirement in the MMEL
Boeing asked that the proposed operational requirement for
airplanes with dual crossfeed valves operating on the master minimum
equipment list (MMEL) be eliminated. Boeing stated that after
publication of AD 88-21-03, which required operational checks of the
crossfeed valves in the last hour of each ETOPS flight for airplanes
equipped with a single crossfeed valve, the FAA approved the
installation of a second crossfeed valve as an AMOC for that AD,
without requiring any crossfeed valve checks if the airplane is
operated with a crossfeed valve inoperative under the MEL. Boeing added
that it is not necessary to now mandate an operational check for an
airplane operating with a crossfeed valve inoperative under the MEL.
Boeing stated that the fundamental criterion for MMEL relief is
that an acceptable level of safety must be maintained considering the
next critical single failure event in flight. Boeing also stated that
operation with a crossfeed valve or transfer system inoperative under
the current MMEL requires verification that the remaining crossfeed
valve is operative, and that in-flight failure of the remaining
crossfeed valve during a subsequent flight would not itself create an
unsafe condition. Boeing added that issuing an AD to require
operational checks for operation under the MMEL is therefore redundant.
Boeing cited the preamble language required by the FAA in MMEL
Policy Letter 34, Revision 4, dated August 15, 1997:
Experience has shown that with the various levels of redundancy
designed into aircraft, operation of every system or installed
component may not be necessary when the remaining operative
equipment can provide an acceptable level of safety.
Boeing stated that the addition of a redundant crossfeed valve
provides a fault-tolerant configuration, which experience has shown
provides an acceptable level of safety. Boeing concluded that unless
credit is given for the redundant crossfeed valve without a requirement
for an operational check, the redundant valve provides no added safety
benefit and therefore could be eliminated.
The FAA does not agree with the commenter's request. When the FAA
determines that an existing MMEL relief provision does not provide an
acceptable level of safety, the FAA may either eliminate or modify that
relief through AD action. In this case, the FAA determined that an
operational check of the crossfeed valve, prior to each ETOPS flight
that takes place with a single crossfeed valve, is necessary to prevent
dispatch of an ETOPS flight with no ability to access all of the
remaining fuel in the event of an engine failure. The FAA has further
determined that flights without the ability to access all of the
remaining fuel would not provide an acceptable level of safety, because
a single engine failure during the critical portion of the cruise phase
could result in a forced offairport landing due to inadequate usable
fuel available to the operative engine. This check is necessary when an
airplane equipped with a dual crossfeed valve is dispatched under the
MMEL with one crossfeed valve inoperative or with the fuel balancing
system inoperative, for the same reason that the crossfeed valve
operational check is required prior to each ETOPS flight on an airplane
with a single crossfeed valve.
The citation from MMEL Policy Letter 34 is from the standardized
language required by that policy letter to be included in the preamble
of an MMEL. It is simply an introductory statement indicating that
redundant systems may allow for dispatch with certain equipment
inoperative in some cases. It is not intended to restrict the
conditions or limitations that the FAA may place on a particular MMEL
relief provision. The failure of a crossfeed valve in a manner that
will prevent it from actuating is typically detected only through
subsequent attempted actuation of the crossfeed valve for fuel
balancing, or for crossfeed in the event of an engine failure.
Therefore, the failure of the crossfeed valve is likely to remain
undiscovered from the time of the failure until the next attempt at
actuation. This latency period may occur during several flights in some
operational situations, such as movement of an individual airplane to
an ETOPS route when that airplane has previously been operated on non-
ETOPS routes. That operational situation and the associated latency
period increases the likelihood that the crossfeed valve on that
airplane will fail when the next attempt is made to actuate the
crossfeed valve. An operational check of the crossfeed valve
immediately prior to each ETOPS flight (the flights where the ability
to open the crossfeed valve may be critical) is a practical measure to
minimize the likelihood that the crossfeed valve will fail to open if
needed, and to ensure that
[[Page 67841]]
the flight is started with an operative crossfeed valve.
The addition of a second crossfeed valve provides redundancy that
the FAA determined in the past was an acceptable substitute for a
preflight operational check, and that also could allow for dispatch
with one crossfeed valve inoperative. However, since that time the FAA
has determined that when an airplane is operated with a crossfeed valve
(or a fuel balancing system) under the MEL, it should be operated with
the same crossfeed valve operational check requirement as an airplane
with a single crossfeed valve configuration, for the same reason that
the preflight operational check is required for an airplane with a
single crossfeed valve configuration. Therefore, the AD has not been
changed in this regard.
Request To Correct Errors in Figure 10
Boeing, UAL, All Nippon Airways (ANA), and Captain David Stewart
(Captain Stewart) asked that the language specified in figure 10 to
paragraph (m) of the proposed AD be corrected to reflect that the
allowed MMEL dispatch relief in that figure is for the fuel balance
system instead of the crossfeed valve. UAL listed four specific MMEL
provisions (specified in paragraphs (m)(1) through (4) of this AD) that
are for various inoperative components or systems that cause the fuel
balance system to be inoperative. Boeing and ANA stated that the figure
should be revised to reflect that if the crossfeed valve fails to open,
the FUEL CROSSFEED advisory message will not be displayed until 15
seconds after crossfeed is selected ON. Captain Stewart stated that the
language in figure 10 to paragraph (m) of the proposed AD is erroneous
and should have stated ``Before the next ETOPS departure after the Fuel
Balance Switch is determined to be inoperative . . . .''
The FAA agrees with the commenters' requests for the reasons
provided. Figure 10 to paragraph (m) of this AD has been revised to
correct the errors noted by the commenters.
Request To Revise the MMEL Operational Check Requirements
United Airlines MEL Engineering asked that the MMEL operational
check requirements in figure 4 to paragraph (h)(2) of the proposed AD,
figure 6 to paragraph (i)(2) of the proposed AD, figure 7 to paragraph
(j) of the proposed AD, and figure 8 to paragraph (k) of the proposed
AD be revised to allow the use of either the ``VALVE'' light that is
integral to the crossfeed valve switch, or the associated engine
indication and crew alerting system (EICAS) message for the preflight
operational check. UAL stated that if the ``VALVE'' light is
inoperative, it would be unable to perform the check. UAL noted that
MMEL relief is provided for the crossfeed valve lights.
The FAA does not agree with the commenter's request to perform the
check using the ``FWD/AFT FUEL CROSSFEED'' EICAS message because there
are certain crossfeed valve actuator failure modes that can cause the
crossfeed valve to remain closed without the ``FWD/AFT FUEL CROSSFEED''
EICAS message being displayed. Short of directly observing the valve
actuator, monitoring the VALVE light to verify that the crossfeed valve
actually transitioned from closed to open is the only way to verify
from the flight deck that the crossfeed valve transitioned to the open
position. While MMEL relief is provided for the VALVE light, that
relief is subject to the provision that the crossfeed valve is verified
to operate correctly.
The FAA does agree to allow an alternative procedure that is
effective if the ``VALVE'' light is inoperative, because it is possible
to perform an operational check of the crossfeed valve by directly
observing the movement of the actuator if the ``VALVE'' light is
inoperative. The FAA has revised the referenced figures in this AD
accordingly.
Request To Revise Crossfeed Valve Operational Check
The Air Line Pilots Association, International (ALPA), Allied
Pilots Association (APA), and Captain Stewart asked for revisions to
the operational checks specified in the proposed AD. Captain Stewart
asked that certain crossfeed valve actions in the proposed AD be
changed to require one of the following: (1) Performing the crossfeed
valve operational check in flight, prior to entering the ETOPS segment
of the flight, and diverting the airplane to a suitable airport if the
check fails, or (2) opening the crossfeed valve prior to entry into the
ETOPS segment, leaving the crossfeed valve open throughout the ETOPS
segment, and diverting the airplane to a suitable airport if the valve
fails to open. Captain Stewart pointed out that operation with the
crossfeed valve open for the duration of the ETOPS portion of the
flight was proven effective at a major airline.
ALPA, while supporting the inclusion of an operational check prior
to dispatch of ETOPS flights, stated that since the action in the
proposed AD is not directed at a specific crossfeed valve failure mode,
and is instead intended to identify and minimize the exposure to any
crossfeed valve failure mode, it is important to check the crossfeed
valve in its normal operating environment during flight. ALPA therefore
requested that the proposed AD be revised to include an AFM requirement
for airplanes with only one crossfeed valve, and a MEL requirement for
airplanes with two crossfeed valves, for an operational check of the
crossfeed valve during cruise, prior to the entering ETOPS airspace.
APA had no objection to the steps for checking the crossfeed valve
operation, using the procedure recommended by the original equipment
manufacturer (OEM). APA recommended checking the crossfeed valve
immediately prior to the ETOPS segment of the flight where its
operation has the potential to be critical.
The FAA does not agree with the commenters' requests. Although the
agency agrees that operationally checking the crossfeed valve
immediately prior to entering the critical ETOPS portion of each ETOPS
flight would provide a greater reduction in the risk that a crossfeed
valve will fail to open in the fuel-critical phase of flight should an
engine failure occur, it would also significantly increase the costs
associated with each discovered failure of a crossfeed valve. The cost
of an air turn-back or diversion is significantly higher than the cost
of a delay for maintenance, and is likely to be greater than the cost
of a flight cancellation. The FAA considered the additional costs that
would be incurred by operators from an air turn-back or diversion each
time a crossfeed valve fails its check, and also considered the
additional reduction in exposure to latent crossfeed valve failures
that develop between the time of a preflight check and the time of an
ETOPS entry check. As a result of these considerations, the FAA
determined that the incremental reduction in exposure to the
development of a latent crossfeed valve failure due to checking the
crossfeed valve in-flight prior to entry into the critical ETOPS
portion of the flight, when the low probability of an engine failure is
also considered, did not justify imposing those significant additional
operational costs and service disruptions on affected operators.
Before the NPRM was published, the FAA discussed with Boeing the
value of conducting the crossfeed valve operational check during flight
under cold soak conditions (which are part of the normal operating
environment), versus performing the check on the ground. As a result of
some of the comments on the NPRM, the agency discussed this issue again
with Boeing, and placed a record of that discussion
[[Page 67842]]
in the public rulemaking docket. Boeing stated that the valve actuator
failure modes identified by other commenters that result in actuator
failures only in cold soak conditions have been corrected in newer
designs. Boeing further stated that the previous valve actuator
configurations that had those issues are no longer in service. Boeing
added that it had no reason to believe that a check of the current in-
service crossfeed valves under cold, in-flight conditions would detect
failures that would not be detected on the ground.
In addition, the FAA does not agree with the request to require
operation with the crossfeed valve open throughout the ETOPS segment of
flight. While operation in that configuration would prevent the need to
open the crossfeed valve in the event of an engine failure, there are
other failure scenarios (such as a large fuel leak or contamination of
one main tank) where operating with the crossfeed valve open
compromises the intended isolation and independence of the fuel system
for each engine. Also, differences in fuel pump performance could cause
the need for repeated switching off and on of fuel pumps to maintain
balanced main tanks. The FAA considers this undesirable because a
flight crew error could put one or both engines on suction feed,
potentially causing engine flameout. It would also add start/stop
cycles on the fuel pumps, which could cause additional pump failures.
Such a procedure is not recommended or approved by either Boeing or the
FAA. Finally, that procedure violates the required fuel usage
procedures in the limitations section of the FAA-approved AFMs for all
of the affected airplane models, which require the airplane to be
operated with the crossfeed valve closed except when it is specifically
required to be open for crossfeeding to maintain balanced main tanks or
for a low fuel condition. Therefore, that procedure would also violate
14 CFR 91.9, which requires operators to operate aircraft in accordance
with their applicable AFM limitations, unless a revised AFM was
approved. In light of all these factors, the AD has not been changed in
this regard.
Request To Change MMEL-Related Requirements
Captain Stewart recommended that the proposed AD be revised to
require an MMEL revision with clearly written provisions that identify
the appropriate verification to confirm that no latent faults exist.
Captain Stewart added that there is no benefit in mandating specific
(M) & (O) procedures in the proposed AD, because it would cause an
unnecessary administrative burden. Captain Stewart concluded that MELs
published without the adequate (M) & (O) procedures indicates a failure
of the MEL review/approval process at the flight standards district
office (FSDO) or certificate management office (CMO) level.
The FAA infers that the commenter is requesting that the MEL
entries for operation with an inoperative crossfeed valve or fuel
balancing system (for Model 787 airplanes) state the requirement for
and objectives of the MEL maintenance and operational requirements,
rather than mandating specific maintenance or operational procedures.
The FAA does not agree with the commenter's request. In this case,
there are various ways that the operational or maintenance check can be
done, some of which would not detect all of the possible crossfeed
valve failure modes. Therefore, the FAA has determined that the agency
should maintain control over the operational and maintenance check
procedures used. Operators may, however, apply for an AMOC in
accordance with paragraph (o) of this AD, provided they can show that
their proposed alternative operational or maintenance procedures
adequately address the unsafe condition. The AD has not been changed in
this regard.
Request To Exempt Certain Airplanes
FedEx asked that the proposed AD be revised to exclude airplanes
that are not used for ETOPS operations from the proposed requirement to
revise the existing AFM and MEL. Specifically, FedEx requested that
paragraphs (h), (i), (j), and (k) of the proposed AD be revised to add
``Airplanes that are not used for ETOPS operations are exempt from the
requirements of this paragraph.'' FedEx stated that the proposed AD
does not allow for exemption of affected fleets that are not certified
or utilized for ETOPS operations. FedEx reported that its fleets
include the types of airplanes affected by the proposed AD, but that
only its Model 777F airplanes are certified for ETOPS operations.
The FAA does not agree with the commenter's request. The addition
of the language proposed by the commenter is not sufficient to ensure
that the existing AFM and MEL will be updated as required by this AD if
there is an operational change in the future. However, operators may
apply for an AMOC in accordance with paragraph (o) of this AD, provided
they submit a proposal that (1) describes how the operator will ensure
that future introduction of ETOPS operations includes the required AFM
and MEL changes and (2) is supported by its FAA POI. The AD has not
been changed in this regard.
Request To Clarify Instructions for Operational Check
FedEx and Japan Airlines (JAL) asked that the language in figure 8
to paragraph (k) of the proposed AD be revised to include instructions
for a fuel crossfeed valve operational check including ``steps on the
ground prior to engine start.'' The commenters requested that ``prior
to engine start'' be changed to ``prior to each flight.'' FedEx stated
that this language should be clarified given that the intent of the
proposed AD is to prevent fuel in the main tank associated with the
failed engine from being unavailable to the remaining operative engine,
potentially resulting in a forced off-airport landing. JAL stated that
the time for performing the operational check in the proposed AD is
more restrictive than that in the MMEL. JAL added that since both are
the same action, that compliance time should be the same.
The FAA acknowledges the commenters' concerns regarding potential
misunderstanding of when to perform the operational check, and agree
that clarification is necessary. The FAA infers that FedEx found that
figure 8 to paragraph (k) of this AD was not sufficiently clear that
the operational check is intended to be performed prior to each flight.
The FAA presumes that FedEx's concern is that an operator might perform
the operational check only once prior to the first engine start after
placing the other inoperative crossfeed valve on MEL relief, but not
prior to subsequent flights on the MEL. The intent of the procedure is
that an operational check of the crossfeed valve be performed, by
maintenance personnel or flightcrew, immediately prior to each ETOPS
flight, as was stated in the ``Proposed AD Requirements'' section of
the NPRM.
The FAA disagrees with using the specific language proposed by
FedEx because its language would not alleviate the confusion about the
intent of the requirement, and might be interpreted as allowing the
check to be performed at any time prior to flight, as opposed to
immediately prior to each flight. Although the comment from FedEx
requested a change to figure 8 to paragraph (k) of this AD, which
provides the required MEL revision for the Model 767, the FAA is
satisfied that the MEL language in figure 7 to paragraph (j) of this
AD, figure 8 to paragraph (k) of this AD, figure 9 to paragraph (l) of
this AD, and figure 10
[[Page 67843]]
to paragraph (m) of this AD is clear with respect to the intended
timing of performing the crossfeed valve operational check.
The general intent of operational procedures in the existing MEL is
that they are associated with each flight conducted with the
inoperative equipment. However, the comments provided caused the agency
to reconsider whether the corresponding language in the AFM revisions
required for airplanes equipped with single crossfeed valves are
sufficiently clear regarding the intended timing for the check. In
light of this, figure 1 to paragraph (g)(1) of this AD, figure 3 to
paragraph (h)(1) of this AD, and figure 5 to paragraph (i)(1) of this
AD of this AD have been revised to clarify the AFM limitations on
airplanes equipped with a single crossfeed valve. However, the language
in other figures, including figure 8 to paragraph (k) of this AD, have
not been changed.
Request To Change Time for Performing Operational Check
DAL asked that the time for performing the operational check be
changed to the last hour of the cruise flight, instead of prior to each
ETOPS flight. DAL stated that solder joint cracks at the connectors and
electronic assembly could cause intermittent or hard fault failure of
the motor-operated crossfeed valves (MOVs) that is difficult to detect
during the ground test prior to each ETOPS flight. DAL added that a
cold soak test at the end of the cruise flight will better detect
intermittent MOV failures than a test performed on the ground.
The FAA does not agree with the commenter's request. At the FAA's
request, Boeing examined the commenter's statements, and Boeing
provided comments. A record of the phone conversation in which Boeing
provided its comments was placed in the public rulemaking docket for
this AD. Boeing stated that the valve actuator failure modes described
by DAL that tended to occur in cold conditions were successfully
addressed by design improvements, and that the valve actuator
configurations that were susceptible to failures that could only be
detected in cold conditions have been replaced on operational aircraft
and are no longer in service. Boeing added that its more recent failure
data shows that the timing of failures is random, and that the ability
to detect a failed crossfeed valve is no longer significantly impacted
by environmental conditions during the operational check.
As previously discussed, the FAA has determined that the greatest
practical reduction in risk during operation with a single operational
crossfeed valve would be achieved by requiring the operational check as
close as possible to the beginning of the fuel-critical ETOPS portion
of the flight. However, as noted, the impact of requiring the
operational check in flight, just prior to entry into the ETOPS portion
of the flight, would cause a significant number of air turn-backs and
diversions at significant cost, so the FAA, with agreement from Boeing,
proposed the check requirement for immediately prior to each ETOPS
flight. Therefore, this AD has not been changed in this regard.
Request To Reduce Compliance Time
ALPA asked that the compliance time be reduced from 120 to 90 days.
ALPA stated that the proposed AD would not require extensive, one-time
maintenance actions on affected airplanes, but only revision of
existing AFM and MEL actions, thus the commenter recommended a shorter
compliance time.
The FAA does not agree with the commenter's request. In conjunction
with Boeing, the FAA has determined that the compliance time for each
airplane model will accommodate the time necessary to accomplish the
actions required by this AD and maintain an adequate level of safety.
In addition, the suggested compliance time change would alter the
requirements of this AD, so additional rulemaking would be required,
ultimately delaying issuance of the AD. The FAA finds that delaying
this action further is inappropriate in light of the identified unsafe
condition. However, if additional data are presented that would justify
a shorter compliance time, the FAA may consider further rulemaking on
this issue. The AD has not been changed in this regard.
Request To Add Airplanes to Applicability
American Airlines asked that Model 737-7, -8, and -9 (MAX)
airplanes be added to the applicability of the proposed AD. American
Airlines stated that the design on these airplanes is similar to that
of the Model 737 Classic and Next Gen airplanes.
The FAA does not agree with the request. Although the commenter is
correct about the similar design, this unsafe condition was identified
at the time of certification of the 737 MAX airplanes as a planned
airworthiness directive against the existing Model 737 airplanes.
Therefore, Boeing included the requirement for the operational check of
the crossfeed valve required by this AD in the FAA-approved AFM for the
737 MAX airplanes. The AD has not been changed in this regard.
Engineering Oversight
Captain Stewart and APA stated that it is an engineering oversight
that new production ETOPS airplanes are being certificated with only
one fuel crossfeed valve installed.
The FAA acknowledges the commenter's concern about the risk
associated with two-engine ETOPS airplanes that depend on a single
active component to allow the remaining engine to access all of the
remaining fuel on board after an engine failure. However, the allowance
for such designs was not an engineering oversight, but a result of how
the initial 120-minute ETOPS type-design standards were developed with
existing airplanes in mind, of the later 180-minute ETOPS type-design
standards being developed based on the 120-minute standards, and of
conscious decision making by Boeing and the FAA associated with AD 88-
21-03 R1 (which applies to certain Airbus Model A300 and A310-200
series airplanes, and Boeing Model 737-200, 737-300, 757-200, 767-200,
and 767-300 series airplanes) and certification of the Model 737-700
airplane. Discussion of the potential need for improvements to
airworthiness standards is outside the scope of the actions required by
this AD. Therefore, the AD has not been changed in this regard.
Report of Incident
Commenter Amirul Ismail provided what appears to be a pilot report
of an instance where an operational check of the crossfeed valve on a
Model 737-800 airplane resulted in the VALVE light failing to
extinguish. The incident appears to be an indication-related fault
rather than a valve actuator failure. No change to the final rule has
been made.
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.
[[Page 67844]]
Costs of Compliance
The FAA estimates that this AD affects 3,252 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
AFM Revision (2,127 airplanes)........ 1 work-hour x $85 per $0 $85 $180,795
hour = $85.
MEL Revision (1,125 airplanes)........ 1 work-hour x $85 per 0 85 95,625
hour = $85.
----------------------------------------------------------------------------------------------------------------
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.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to transport category airplanes and
associated appliances to the Director of the System Oversight Division.
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):
2019-19-10 The Boeing Company: Amendment 39-19746; Docket No. FAA-
2017-1024; Product Identifier 2017-NM-065-AD.
(a) Effective Date
This AD is effective January 16, 2020.
(b) Affected ADs
This AD affects AD 88-21-03 R1, Amendment 39-6077 (53 FR 46605,
November 18, 1988) (``AD 88-21-03 R1'').
(c) Applicability
This AD applies to all The Boeing Company airplanes,
certificated in any category, identified in paragraphs (c)(1)
through (5) of this AD.
(1) Model 737-300, -400, -500, -600, -700, -700C, -800, -900,
and -900ER series airplanes.
(2) Model 757-200, -200PF, -200CB, and -300 series airplanes.
(3) Model 767-200, -300, -300F, and -400ER series airplanes.
(4) Model 777-200, -200LR, -300, -300ER, and -777F series
airplanes.
(5) Model 787-8 and 787-9 airplanes.
(d) Subject
Air Transport Association (ATA) of America Code 28; Fuel.
(e) Unsafe Condition
This AD was prompted by reports of fuel crossfeed valves failing
to open when activated during flight. The FAA is issuing this AD to
prevent an airplane from being dispatched on an extended operations
(ETOPS) flight with a single fuel crossfeed valve (due to design or
due to minimum equipment list (MEL) dispatch of a dual crossfeed
valve equipped airplane with one crossfeed valve inoperative) that
cannot be opened or a fuel balancing system that cannot properly
operate when activated. This condition could cause the fuel in the
main tank associated with a failed engine to be unavailable to the
remaining operative engine, potentially resulting in a forced off
airport landing due to exhaustion of the remaining usable fuel and
consequent loss of all engine thrust.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) AFM Revisions for Model 737 Airplanes Equipped With a Single Fuel
Crossfeed Valve
For airplanes identified in paragraph (c)(1) of this AD: Within
120 days after the effective date of this AD, do the actions
specified in paragraphs (g)(1) and (2) of this AD.
(1) Revise the ``Extended Range Operations'' subsection of the
``Fuel System Limitations'' section of the Section 1 Certificate
Limitations of the existing airplane flight manual (AFM) by
incorporating the information specified in figure 1 to paragraph
(g)(1) of this AD. This may be done by inserting a copy of this AD
into the existing AFM. When a statement identical to that in figure
1 to paragraph (g)(1) of this AD has been included in the ``Extended
Range Operations'' subsection of the ``Fuel System Limitations''
section of the Section 1 Certificate Limitations of the general
revisions of the existing AFM, the general revisions may be inserted
into the existing AFM, and the copy of this AD may be removed from
the existing AFM.
[[Page 67845]]
[GRAPHIC] [TIFF OMITTED] TR12DE19.000
(2) Revise the ``Extended Range Operations'' section of the
Section 3 Normal Procedures of the existing AFM by incorporating the
information specified in figure 2 to paragraph (g)(2) of this AD.
This may be done by inserting a copy of this AD into the existing
AFM. When a statement identical to that in figure 2 to paragraph
(g)(2) of this AD has been included in the ``Extended Range
Operations'' section of Section 3 Normal Procedures of the existing
AFM, the general revisions may be inserted into the existing AFM,
and the copy of this AD may be removed from the existing AFM.
[GRAPHIC] [TIFF OMITTED] TR12DE19.001
(h) AFM Revisions for Model 757 Airplanes Equipped With a Single Fuel
Crossfeed Valve
For airplanes identified in paragraph (c)(2) of this AD having
line numbers 1 through 518 inclusive, on which the actions specified
in Boeing Service Bulletin 757-28-0029 (second fuel crossfeed valve
installation) have not been done: Within 120 days after the
effective date of this AD, do the actions specified in paragraphs
(h)(1) and (2) of this AD. For Model 757 airplanes identified in
this paragraph, if the actions specified in Boeing Service Bulletin
757-28-0029 have been done, the actions specified in this paragraph
are no longer required for that airplane and the actions specified
in paragraph (j) of this AD must be done before further flight after
the actions specified in Boeing Service Bulletin 757-28-0029 have
been performed.
(1) Revise the ``Extended Range Operations'' section of the
Section 1 Certificate Limitations of the existing AFM by
incorporating the information specified in figure 3 to paragraph
(h)(1). This may be done by inserting a copy of this AD into the
existing AFM. When a statement identical to that in figure 3 to
paragraph (h)(1) of this AD has been included in the ``Extended
Range Operations'' section of the Section 1 Certificate Limitations
of the general revisions of the existing AFM, the general revisions
may be inserted into the existing AFM, and the copy of this AD may
be removed from the existing AFM.
[[Page 67846]]
[GRAPHIC] [TIFF OMITTED] TR12DE19.002
(2) Revise the ``Extended Range Operations'' section of Section
3 Normal Procedures of the existing AFM by incorporating the
information specified in figure 4 to paragraph (h)(2) of this AD.
This may be done by inserting a copy of this AD into the existing
AFM. When a statement identical to that in figure 4 to paragraph
(h)(2) of this AD has been included in the ``Extended Range
Operations'' section of Section 3 Normal Procedures of the existing
AFM, the general revisions may be inserted into the existing AFM,
and the copy of this AD may be removed from the existing AFM.
[GRAPHIC] [TIFF OMITTED] TR12DE19.003
(i) AFM Revisions for Model 767 Airplanes Equipped With a Single Fuel
Crossfeed Valve
For airplanes identified in paragraph (c)(3) of this AD having
line numbers 1 through 430 inclusive on which the actions specified
in Boeing Service Bulletin 767-28-0034 (second fuel crossfeed valve
installation) have not been done as of the effective date of this
AD: Within 120 days after the effective date of this AD, do the
actions specified in paragraphs (i)(1) and (2) of this AD. For
airplanes on which the actions specified in Boeing Service Bulletin
767-28-0034 have been done, the actions specified in this paragraph
are no longer required for that airplane and the actions specified
in paragraph (k) of this AD must be done before further flight.
(1) Revise the ``Extended Range Operations'' section of the
Section 1 Certificate Limitations of the existing AFM by
incorporating the information specified in figure 5 to paragraph
(i)(1) of this AD. This may be done by inserting a copy of this AD
into the existing AFM. When a statement identical to that in figure
5 to paragraph (i)(1) of this AD has been included in the ``Extended
Range Operations'' section of the Section 1 Certificate Limitations
of the general revisions of the existing AFM, the general revisions
may be inserted into the existing AFM, and the copy of this AD may
be removed from the existing AFM.
[[Page 67847]]
[GRAPHIC] [TIFF OMITTED] TR12DE19.004
(2) Revise the ``Extended Range Operations'' section of Section
3.1 Normal Procedures of the existing AFM by incorporating the
information specified in figure 6 to paragraph (i)(2) of this AD.
This may be done by inserting a copy of this AD into the existing
AFM. When a statement identical to that in figure 6 to paragraph
(i)(2) of this AD has been included in the ``Extended Range
Operations'' section of Section 3.1 Normal Procedures of the
existing AFM, the general revisions may be inserted into the
existing AFM, and the copy of this AD may be removed from the
existing AFM.
[GRAPHIC] [TIFF OMITTED] TR12DE19.005
(j) MEL Revisions for Model 757 Airplanes Equipped With Dual Fuel
Crossfeed Valves
For airplanes identified in paragraph (c)(2) of this AD having
line numbers 519 and subsequent; and for airplanes identified in
paragraph (c)(2) of this AD having line numbers 1 through 518
inclusive, on which a second fuel crossfeed valve has been
installed, as specified in Boeing Service Bulletin 757-28-0029:
Within 120 days after the effective date of this AD, revise the
operator's existing FAA-approved MEL by incorporating the
information specified in figure 7 to paragraph (j) of this AD as a
required operations procedure when dispatching for ETOPS operation
with an inoperative fuel crossfeed valve. Specific alternative MEL
wording to accomplish the actions specified in figure 7 to paragraph
(j) of this AD can be approved by the operator's principal
operations inspector (POI).
[[Page 67848]]
[GRAPHIC] [TIFF OMITTED] TR12DE19.006
(k) MEL Revisions for Model 767 Airplanes Equipped With Dual Fuel
Crossfeed Valves
For airplanes identified in paragraph (c)(3) of this AD having
line numbers 431 and subsequent; and for airplanes identified in
paragraph (c)(3) of this AD having line numbers 1 through 430
inclusive on which a second fuel crossfeed valve has been installed,
as specified in Boeing Service Bulletin 767-28-0034: Within 120 days
after the effective date of this AD, revise the operator's existing
FAA-approved MEL by incorporating the information specified in
figure 8 to paragraph (k) of this AD as a required operations
procedure when dispatching for ETOPS operation with an inoperative
fuel crossfeed valve. Specific alternative MEL wording to accomplish
the actions specified in figure 8 to paragraph (k) of this AD can be
approved by the operator's POI.
[GRAPHIC] [TIFF OMITTED] TR12DE19.007
(l) MEL Revisions for Model 777 Airplanes
For airplanes identified in paragraph (c)(4) of this AD: Within
120 days after the effective date of this AD, revise the operator's
existing FAA-approved MEL by incorporating the information specified
in figure 9 to paragraph (l) of this AD as a required operations
procedure when dispatching for ETOPS operation with an inoperative
fuel crossfeed valve. Specific alternative MEL wording to accomplish
the actions specified in figure 9 to paragraph (l) of this AD can be
approved by the operator's POI.
[[Page 67849]]
[GRAPHIC] [TIFF OMITTED] TR12DE19.008
(m) MEL Revisions for Model 787 Airplanes
For airplanes identified in paragraph (c)(5) of this AD: Within
120 days after the effective date of this AD, revise the operator's
existing FAA-approved MEL by incorporating the information specified
in figure 10 to paragraph (m) of this AD into the MEL requirements
for each of the inoperative items specified in paragraphs (m)(1)
through (4) of this AD. Specific alternative MEL wording to
accomplish the actions specified in figure 10 to paragraph (m) of
this AD can be approved by the operator's POI.
(1) 28-21-01-01 Pressure Refueling System, Main Tank Inboard
Refuel Valve.
(2) 28-22-06 Fuel Balance Switch.
(3) 28-26-01 Defuel/Isolation Valves.
(4) 28-41-01-01 Main Tank Fuel Quantity Indication Systems.
[[Page 67850]]
[GRAPHIC] [TIFF OMITTED] TR12DE19.009
(n) AD 88-21-03 R1 AFM Limitation Removal
After the applicable AFM limitations specified in paragraphs
(g)(1), (h)(1), and (i)(1) of this AD are incorporated into an
airplane's existing AFM, operators may remove the AFM limitation
required by AD 88-21-03 R1, for that airplane.
(o) 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 (p) 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.
(p) 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].
[[Page 67851]]
(q) Material Incorporated by Reference
None.
Issued in Des Moines, Washington, on October 3, 2019.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification
Service.
[FR Doc. 2019-26736 Filed 12-11-19; 8:45 am]
BILLING CODE 4910-13-P