Rule2026-21863
Airworthiness Directives; The Boeing Company Airplanes
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
October 27, 2026
Effective
December 1, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes. This AD was prompted by a leak through the form-in-place (FiP) gasket found during a leak check. This AD requires a detailed inspection of the FiP gasket at the engine fuel shutoff valve access panel for correct sealant installation, or a detailed inspection at the engine fuel shutoff valve access panel for any damage on the preformed seal, depending on configuration; a fluid leak test of the engine fuel shutoff valve access panel for any leak; and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
<html>
<head>
<title>Federal Register, Volume 91 Issue 206 (Tuesday, October 27, 2026)</title>
</head>
<body><pre>
[Federal Register Volume 91, Number 206 (Tuesday, October 27, 2026)]
[Rules and Regulations]
[Pages 67452-67455]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-21863]
[[Page 67452]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-2716; Project Identifier AD-2025-00990-T;
Amendment 39-23496; AD 2026-21-07]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes.
This AD was prompted by a leak through the form-in-place (FiP) gasket
found during a leak check. This AD requires a detailed inspection of
the FiP gasket at the engine fuel shutoff valve access panel for
correct sealant installation, or a detailed inspection at the engine
fuel shutoff valve access panel for any damage on the preformed seal,
depending on configuration; a fluid leak test of the engine fuel
shutoff valve access panel for any leak; and applicable on-condition
actions. The FAA is issuing this AD to address the unsafe condition on
these products.
DATES: This AD is effective December 1, 2026. The Director of the
Federal Register approved the incorporation by reference of a certain
publication listed in this AD as of December 1, 2026.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-2716; or in person at Docket Operations between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD
docket contains this final rule, any comments received, and other
information. The address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
<bullet> For Boeing material identified in this AD, 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; website <a href="http://myboeingfleet.com">myboeingfleet.com</a>.
<bullet> You may view this material at the FAA, Airworthiness
Products Section, Operational Safety 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 at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-2716.
FOR FURTHER INFORMATION CONTACT: Erica Bayles, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 907-
271-5844; email: <a href="/cdn-cgi/l/email-protection#5f3a2d363c3e713a713d3e26333a2c1f393e3e71383029"><span class="__cf_email__" data-cfemail="3055425953511e551e5251495c5543705651511e575f46">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain The Boeing
Company Model 737-8, 737-9, and 737-8200 airplanes. The NPRM was
published in the Federal Register on March 23, 2026 (91 FR 13791). The
NPRM was prompted by a leak through the FiP gasket at the engine fuel
shutoff valve access panel found during a leak check, completed as part
of a nonconformance disposition for the Boeing Company Model 737-8,
737-9, and 737-8200 airplanes. An investigation found that the fairing
requirements of the engine fuel shutoff valve access panel caused thin
regions of the FiP gasket, which caused the manufacturer to apply non-
permitted sealant after the initial FiP gasket had cured, resulting in
an uneven sealing surface on the engine fuel shutoff valve access panel
and a fuel leak. In the NPRM, the FAA proposed to require a detailed
inspection of the FiP gasket at the engine fuel shutoff valve access
panel for correct sealant installation, or a detailed inspection at the
engine fuel shutoff valve access panel for any damage on the preformed
seal, depending on configuration; a fluid leak test of the engine fuel
shutoff valve access panel for any leak; and applicable on-condition
actions. The FAA is issuing this AD to address incorrect or missing
sealant installation. The unsafe condition, if not addressed, could
result in fuel leaking onto the engine exhaust nozzle and a possible
fire on the ground.
Discussion of Final Airworthiness Directive
Comments
The FAA received a comment from the Air Line Pilots Association,
International (ALPA) who supported the NPRM without change.
The FAA received additional comments from American Airlines
(American) and Southwest Airlines (Southwest). The following presents
the comments received on the NPRM and the FAA's response to each
comment.
Request To Combine Proposed ADs
American requested that the FAA revise the proposed AD by
incorporating the affected airplanes and proposed requirements from
another proposed AD (Docket No. FAA-2026-2725, Project Identifier AD-
2025-00999-T) and then rescind that other proposed AD. American noted,
although the proposed ADs reference different service information and
different airplane models, both proposed ADs would mandate similar
corrective requirements. American stated consolidating these actions
into a single NPRM would improve clarity and enhance compliance
management without changing the technical intent of the inspection or
impacting airplane airworthiness.
The FAA disagrees with this request. The FAA acknowledges that some
operators may prefer to address the unsafe condition with a single AD;
however, other operators may prefer that the FAA issue two separate
ADs. Additionally, when the manufacturer develops two separate service
bulletins to address an unsafe condition on different airplane models,
proceeding with two separate ADs, in general, allows the FAA to address
the unsafe condition on all airplane models in a timely manner. For
example, if development of one service bulletin is delayed, the
rulemaking process would be delayed for all affected airplane models.
Request To Remove Exceptions to Service Information Instructions
American requested that the FAA remove the exceptions in paragraphs
(h)(3), (5), and (6) from the proposed AD and instead adopt the
instructions in the compliance tables and appendices of Boeing Alert
Requirements Bulletin 737-57A1358 RB, dated November 17, 2025 (the
Boeing Alert Requirements Bulletin). American stated that the language
in the service information sufficiently defines the corrective action
by referencing figure 4, and that retaining this information helps
maintain consistency and minimizes the potential for misinterpretation.
The FAA notes that the exceptions in paragraph (h)(3) are necessary
because the ``on-condition corrective action(s)'' in tables 1 and 2 of
the Compliance and Accomplishment Instructions of the Boeing Alert
Requirements Bulletin are not defined in that bulletin. Similarly, the
exceptions in paragraphs (h)(5) and (6) are necessary because
Appendices A and B of the Boeing Alert Requirements Bulletin do not
explicitly specify to replace the FiP gasket if the fluid leak
[[Page 67453]]
test fails. Therefore, the exceptions in paragraphs (h)(3), (5), and
(6) are necessary to clarify what on-condition corrective actions must
be taken after a fluid leak test failure. The FAA has not revised this
AD in response to this comment.
Request To Clarify Post-AD Requirements
Southwest asked if the FAA agrees that, after completing the
actions required by this AD, an alternative method of compliance (AMOC)
is not required to maintain the airplane per the Boeing aircraft
maintenance manual (AMM). Southwest stated a certain task in the Boeing
AMM provides instructions that vary subtly from the procedures in the
Boeing Alert Requirements Bulletin.
The FAA agrees that an AMOC is not needed to maintain the airplane
after complying with the requirements of this AD if the airplane is
maintained per the Boeing AMM. The FAA notes that the unsafe condition
was introduced during airplane production through the application of
non-permitted sealant after the initial FiP gasket had cured. Since the
FAA has not received any reports of in-service events where anomalies
were introduced during maintenance based on AMM instructions, the FAA
considers the relevant AMM tasks to be appropriate. Further, Boeing has
updated the AMM task to include notes to prevent sealant touch-up after
the initial sealant application. Boeing has also updated the AMM
procedures for the fluid leak test to match the procedures in the
Boeing Alert Requirements Bulletin. Those updates in the AMM
instructions are expected to support operators for improved maintenance
of the FiP gasket or preformed seal installed at the engine fuel
shutoff valve access panel.
Conclusion
The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, this
AD is adopted as proposed in the NPRM. None of the changes will
increase the economic burden on any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Boeing Alert Requirements Bulletin 737-57A1358 RB,
dated November 17, 2025. This material specifies procedures for a
detailed inspection of the FiP gasket at the engine fuel shutoff valve
access panel of the left and right wing for correct sealant
installation, or a detailed inspection at the engine fuel shutoff valve
access panel of the left and right wings for any damage on the
preformed seal, depending on configuration; a fluid leak test of the
engine fuel shutoff valve access panel for any leak; and applicable on-
condition actions. On-condition actions include replacing the FiP
gasket, repairing damage to the preformed gasket, and repeating the
leak test until no leak is found.
This material is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in the ADDRESSES section.
Costs of Compliance
The FAA estimates that this AD affects 433 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per
Action Labor cost Parts cost product Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
Inspection for sealant application.. 1 work-hours x $85 per $0 $85 Up to $36,805.
hour = $85.
Inspection for damage............... 1 work-hour x $85 per 0 85 Up to $36,805.
hour = $85.
Leak test........................... 1 work-hour x $85 per 0 85 $36,805.
hour = $85.
----------------------------------------------------------------------------------------------------------------
The FAA estimates the following costs to do any necessary
replacements that would be required based on the results of the
inspection. The agency has no way of determining the number of aircraft
that might need these replacements:
On-Condition Costs
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Replacement.......................... Up to 3 work-hours x Up to $1,000........... Up to $1,255.
$85 per hour = $255.
----------------------------------------------------------------------------------------------------------------
The FAA has received no definitive data on which to base the cost
estimates for the on-condition repairs to the preformed gasket
specified in this AD.
The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some or all of the costs of
this AD may be covered under warranty, thereby reducing the cost impact
on affected operators.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and
[[Page 67454]]
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.
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:
2026-21-07 The Boeing Company: Amendment 39-23496; Docket No. FAA-
2026-2716; Project Identifier AD-2025-00990-T.
(a) Effective Date
This airworthiness directive (AD) is effective December 1, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company Model 737-8, 737-9, and
737-8200 airplanes, certificated in any category, as identified in
Boeing Alert Requirements Bulletin 737-57A1358 RB, dated November
17, 2025.
(d) Subject
Air Transport Association (ATA) of America Code 57, Wings.
(e) Unsafe Condition
This AD was prompted by a leak through the form-in-place (FiP)
gasket found during a leak check. An investigation found that the
fairing requirements of the engine fuel shutoff valve access panel
caused thin regions of the FiP gasket, which caused non-permitted
sealant to be applied after the initial FiP gasket had cured,
resulting in an uneven sealing surface on the engine fuel shutoff
valve access panel and a fuel leak. The FAA is issuing this AD to
address incorrect sealant installation and damage to preformed
seals. The unsafe condition, if not addressed, could result in fuel
leaking onto the engine nozzle and a consequent fire on the ground.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
Except as specified by paragraph (h) of this AD: At the
applicable times specified in the ``Compliance'' paragraph of Boeing
Alert Requirements Bulletin 737-57A1358 RB, dated November 17, 2025,
do all applicable actions identified in, and in accordance with, the
Accomplishment Instructions of Boeing Alert Requirements Bulletin
737-57A1358 RB, dated November 17, 2025.
Note 1 to paragraph (g): Guidance for accomplishing the actions
required by this AD can be found in Boeing Alert Service Bulletin
737-57A1358, dated November 17, 2025, which is referred to in Boeing
Alert Requirements Bulletin 737-57A1358 RB, dated November 17, 2025.
(h) Exceptions to Requirements Bulletin Specifications
(1) Where the Compliance Time columns of the tables in the
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
57A1358 RB, dated November 17, 2025, refer to the original issue
date of Requirements Bulletin 737-57A1358 RB, this AD requires using
the effective date of this AD.
(2) Where Boeing Alert Requirements Bulletin 737-57A1358 RB,
dated November 17, 2025, specifies contacting Boeing for repair
instructions: This AD requires doing the repair using a method
approved in accordance with the procedures specified in paragraph
(i) of this AD.
(3) Where Table 1 and Table 2 in Boeing Alert Requirements
Bulletin 737-57A1358 RB, dated November 17, 2025, specifies ``Do a
fluid leak test of the engine fuel shutoff valve access panel for
any leak. If any leak is found, do all applicable on-condition
corrective action(s) and repeat the leak test until no leak is
found'', this AD requires replacing that text with ``Do a fluid leak
test of the engine fuel shutoff valve access panel for any leak. If
any leak is found, replace the FiP gasket and repeat the leak test
until no leak is found''.
(4) Where Table 3 and Table 4 in Boeing Alert Requirements
Bulletin 737-57A1358 RB, dated November 17, 2025, specifies ``Do a
fluid leak test of the engine fuel shutoff valve access panel for
any leak. If any leak is found, do all applicable on-condition
corrective action(s) and repeat the leak test until no leak is
found'', this AD requires replacing that text with ``Do a fluid leak
test of the engine fuel shutoff valve access panel for any leak. If
any leak is found, replace the existing sealant installation with a
removable fay seal and repeat the leak test until no leak is
found''.
(5) Where step 4.b. of Appendix A in Boeing Alert Requirements
Bulletin 737-57A1358 RB, dated November 17, 2025, specifies ``If any
water leaks from the engine fuel shutoff valve access panel in less
than two minutes, the fluid leak test has failed'', this AD requires
replacing that text with ``If any water leaks from the engine fuel
shutoff valve access panel in less than two minutes, the fluid leak
test has failed. Replace the FiP gasket in accordance with Figure 3
(Group 1) and removable fay seal in accordance with Figure 7 (Group
2), and repeat the leak test until no leak is found''.
(6) Where step 4.b. of Appendix B in Boeing Alert Requirements
Bulletin 737-57A1358 RB, dated November 17, 2025, specifies ``If any
water leaks from the engine fuel shutoff valve access panel in less
than two minutes, the fluid leak test has failed'', this AD requires
replacing that text with ``If any water leaks from the engine fuel
shutoff valve access panel in less than two minutes, the fluid leak
test has failed. Replace the FiP gasket in accordance with Figure 4
(Group 1) and removable fay seal in accordance with Figure 8 (Group
2), and repeat the leak test until no leak is found''.
(i) Alternative Methods of Compliance (AMOCs)
(1) The Manager, AIR-520, Continued Operational Safety 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
responsible Flight Standards Office, as appropriate. If sending
information directly to the manager of the Continued Operational
Safety Branch, send it to the attention of the person identified in
paragraph (j)(1) of this AD. Information may be emailed to:
<a href="/cdn-cgi/l/email-protection#27666a68646741464609404851"><span class="__cf_email__" data-cfemail="aeefe3e1edeec8cfcf80c9c1d8">[email protected]</span></a>. Before using any approved AMOC, notify your
appropriate principal inspector, or lacking a principal inspector,
the manager of the responsible Flight Standards Office.
(2) 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, AIR-
520, Continued Operational Safety Branch, FAA, to make those
findings. To be approved, the repair method, modification deviation,
or alteration deviation must meet the certification basis of the
airplane, and the approval must specifically refer to this AD.
(j) Additional Information
(1) For more information about this AD, contact Erica Bayles,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 907-271-5844; email: <a href="/cdn-cgi/l/email-protection#a2c7d0cbc1c38cc78cc0c3dbcec7d1e2c4c3c38cc5cdd4"><span class="__cf_email__" data-cfemail="5237203b31337c377c30332b3e3721123433337c353d24">[email protected]</span></a>.
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (k)(3)
of this AD.
(k) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference of the material listed in this paragraph
under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions
required by this AD, unless the AD specifies otherwise.
(i) Boeing Alert Requirements Bulletin 737-57A1358 RB, dated
November 17, 2025.
(ii) [Reserved]
[[Page 67455]]
(3) For Boeing material identified in this AD, 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; website <a href="http://myboeingfleet.com">myboeingfleet.com</a>.
(4) You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 2200 South 216th St.,
Des Moines, WA. For information on the availability of this material
at the FAA, call 206-231-3195.
(5) You may view this material at the National Archives and
Records Administration (NARA). For information on the availability
of this material at NARA, visit <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#8ee8fca0e7e0fdfeebedfae7e1e0cee0effcefa0e9e1f8"><span class="__cf_email__" data-cfemail="a0c6d28ec9ced3d0c5c3d4c9cfcee0cec1d2c18ec7cfd6">[email protected]</span></a>.
Issued on October 20, 2026.
Lona C. Saccomando,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2026-21863 Filed 10-26-26; 8:45 am]
BILLING CODE 4910-13-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on October 27, 2026.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.