Rule2026-09535
Airworthiness Directives; The Boeing Company Airplanes
Primary source
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Published
May 13, 2026
Effective
June 17, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD was prompted by a report of cracks found in the fuselage skin underneath the aft drain mast. This AD requires repetitive inspections of the fuselage skin and structure common to the aft drain mast for any crack or corrosion and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 92 (Wednesday, May 13, 2026)</title>
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[Federal Register Volume 91, Number 92 (Wednesday, May 13, 2026)]
[Rules and Regulations]
[Pages 26895-26897]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-09535]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-1324; Project Identifier AD-2025-00986-T;
Amendment 39-23334; AD 2026-09-12]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and
-500 series airplanes. This AD was prompted by a report of cracks found
in the fuselage skin underneath the aft drain mast. This AD requires
repetitive inspections of the fuselage skin and structure common to the
aft drain mast for any crack or corrosion and applicable on-condition
actions. The FAA is issuing this AD to address the unsafe condition on
these products.
DATES: This AD is effective June 17, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of June 17,
2026.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-1324; 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-2026-1324.
FOR FURTHER INFORMATION CONTACT: Wayne Ha, Aviation Safety Engineer,
FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 562-627-5238;
email: <a href="/cdn-cgi/l/email-protection#bbccdac2d5de95d3dafbdddada95dcd4cd"><span class="__cf_email__" data-cfemail="e99e8890878cc78188a98f8888c78e869f">[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 737-100, -200, -200C, -300, -400, and -500 series
airplanes. The NPRM was published in the Federal Register on February
13, 2026 (91 FR 6798). The NPRM was prompted by a report of cracks
found in the fuselage skin underneath the aft drain mast. In the NPRM,
the FAA proposed to require repetitive inspections of the fuselage skin
and structure common to the aft drain mast for any crack or corrosion
and applicable on-condition actions. The FAA is issuing this AD to
address cracking or corrosion in the fuselage skin and structure common
to the aft drain mast. This condition, if not addressed, could result
in the inability of the principal structural element (PSE) to sustain
limit loads, which may result in rapid decompression of the fuselage
and loss of structural integrity of the airplane.
Discussion of Final Airworthiness Directive
Comments
The FAA received comments from Aviation Partners Boeing and Boeing
who supported the NPRM without change.
[[Page 26896]]
Conclusion
The FAA reviewed the relevant data 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 Service Bulletin 737-53A1409,
Revision 1, dated October 27, 2023. This material specifies procedures
for repetitive internal detailed inspections around the fastener holes,
cutout, channel, and fillers of the structure common to the aft drain
mast (also referred to as the ``aft waste water drain mast'') for any
crack or corrosion; repetitive external detailed inspections and
external surface high frequency eddy current (HFEC) inspections around
the fastener holes and cutout on the fuselage skin common to the aft
drain mast for any crack or corrosion; and applicable on-condition
actions. On-condition actions include obtaining and following repair
instructions. 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 123 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
Estimated Costs
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Cost on U.S.
Action Labor cost Parts cost Cost per product operators
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Repetitive inspections........... 7 work-hours x $85 $0 $595 per inspection $73,185 per
per hour = $595 cycle. inspection cycle.
per inspection
cycle.
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The FAA has received no definitive data on which to base the cost
estimates for the on-condition actions specified in this AD.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
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:
2026-09-12 The Boeing Company: Amendment 39-23334; Docket No. FAA-
2026-1324; Project Identifier AD-2025-00986-T.
(a) Effective Date
This airworthiness directive (AD) is effective June 17, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any
category, as identified in Boeing Alert Service Bulletin 737-
53A1409, Revision 1, dated October 27, 2023.
(d) Subject
Air Transport Association (ATA) of America Code 53, Fuselage.
(e) Unsafe Condition
This AD was prompted by a report of cracks found in the fuselage
skin underneath the aft drain mast. The FAA is issuing this AD to
address cracking or corrosion in the fuselage skin and structure
common to the aft drain mast. The unsafe condition, if not
addressed, could result in the inability of the principal structural
element (PSE) to sustain limit loads, which may result in rapid
decompression of the fuselage and loss of structural integrity of
the airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions for Group 1 Airplanes
For airplanes identified as Group 1 in Boeing Alert Service
Bulletin 737-53A1409, Revision 1, dated October 27, 2023: Within 120
days after the effective date of this AD, inspect the fuselage skin
and structure common to the aft drain mast for any crack or
corrosion and applicable on-condition actions, using a method
approved in accordance with the procedures specified in paragraph
(k) of this AD.
(h) Required Actions for Group 2 Airplanes
For airplanes identified as Group 2 in Boeing Alert Service
Bulletin 737-53A1409, Revision 1, dated October 27, 2023: Except as
specified in paragraph (i) of this AD, at the applicable times
specified in paragraph 1.E.,
[[Page 26897]]
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1409,
Revision 1, dated October 27, 2023, do all applicable actions
identified in, and in accordance with, paragraphs 3.B.2., ``Action
1: Do Part 2,'' and 3.B.3., ``Action 2: Do Part 3,'' of the
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1409, Revision 1, dated October 27, 2023.
(i) Exceptions to Service Bulletin Specifications
(1) Where the Compliance Time columns of the tables in the
``Compliance'' paragraph of Boeing Alert Service Bulletin 737-
53A1409, Revision 1, dated October 27, 2023, refer to the original
issue date of Service Bulletin 737-53A1409, this AD requires using
the effective date of this AD.
(2) Where Boeing Alert Service Bulletin 737-53A1409, Revision 1,
dated October 27, 2023, specifies contacting Boeing for repair
instructions: This AD requires doing the repair using a method
approved in accordance with the procedures specified in paragraph
(k) of this AD.
(j) Credit for Previous Actions
This paragraph provides credit for the actions specified in
paragraphs (g) and (h) of this AD, as applicable, if those actions
were performed before the effective date of this AD using Boeing
Alert Service Bulletin 737-53A1409, dated May 4, 2023.
(k) 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 (l) of this AD. Information may be emailed to:
<a href="/cdn-cgi/l/email-protection#3c7d71737f7c5a5d5d125b534a"><span class="__cf_email__" data-cfemail="c2838f8d8182a4a3a3eca5adb4">[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.
(l) Additional Information
(1) For more information about this AD, contact Wayne Ha,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 562-627-5238; email: <a href="/cdn-cgi/l/email-protection#7502140c1b105b1d14351314145b121a03"><span class="__cf_email__" data-cfemail="93e4f2eafdf6bdfbf2d3f5f2f2bdf4fce5">[email protected]</span></a>.
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (m)(3)
of this AD.
(m) 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 Service Bulletin 737-53A1409, Revision 1, dated
October 27, 2023.
(ii) [Reserved]
(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#b5d3c79bdcdbc6c5d0d6c1dcdadbf5dbd4c7d49bd2dac3"><span class="__cf_email__" data-cfemail="0a6c78246364797a6f697e6365644a646b786b246d657c">[email protected]</span></a>.
Issued on April 28, 2026.
Brian Knaup,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2026-09535 Filed 5-12-26; 8:45 am]
BILLING CODE 4910-13-P
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