[Federal Register Volume 91, Number 30 (Friday, February 13, 2026)]
[Proposed Rules]
[Pages 6798-6801]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-02912]
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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]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain The Boeing Company Model 737-100, -200, -200C, -300, -400,
and -500 series airplanes. This proposed AD was prompted by a report of
cracks found in the fuselage skin underneath the aft drain mast. This
proposed AD would 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 proposing this AD to
address the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by March 30,
2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to regulations.gov. Follow
the instructions for submitting comments.
Fax: 202-493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
AD Docket: You may examine the AD docket at regulations.gov 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 NPRM, any comments received, and other
information. The street address for Docket Operations is listed above.
Material Incorporated by Reference:
For Boeing material identified in this proposed AD,
contact Boeing Commercial Airplanes, Attention: Contractual & Data
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA
90740-5600; telephone
[[Page 6799]]
562-797-1717; website myboeingfleet.com.
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 regulations.gov 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: [email protected].
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments using a method listed
under the ADDRESSES section. Include ``Docket No. FAA-2026-1324;
Project Identifier AD-2025-00986-T'' at the beginning of your comments.
The most helpful comments reference a specific portion of the proposal,
explain the reason for any recommended change, and include supporting
data. The FAA will consider all comments received by the closing date
and may amend this proposal because of those comments.
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this NPRM.
Confidential Business Information
CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as ``PROPIN.'' The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to Wayne
Ha, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 562-627-5238; email: [email protected]. Any commentary
that the FAA receives that is not specifically designated as CBI will
be placed in the public docket for this rulemaking.
Background
The FAA has received a report indicating that two cracks were found
on a 737-400 airplane, measuring 0.4 inches and 0.6 inches in length,
located in the fuselage skin underneath the aft drain mast. The
airplane had accumulated 30,684 flight hours and 30,735 flight cycles.
Boeing has determined that cracks in this location could be caused by
local elevated skin stress from the elliptical cutout, aerodynamic
loading effects, and minor skin defects. 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.
FAA's Determination
The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.
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.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions in the
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1409, Revision 1, dated October 27, 2023, already described, except
as discussed under ``Differences Between this Proposed AD and the
Referenced Material,'' and except for any differences identified as
exceptions in the regulatory text of this proposed AD. For information
on the procedures and compliance times, see this material at
regulations.gov under Docket No. FAA-2026-1324.
Differences Between This Proposed AD and the Referenced Material
Although the actions in paragraph 3.B. of the Accomplishment
Instructions of Boeing Alert Service Bulletin 737-53A1409, Revision 1,
dated October 27, 2023, instruct Group 2 airplanes to accomplish Part 1
through 4 of the Work Instructions, this proposed AD would only require
the accomplishment of Parts 2 and Part 3 of the Work Instructions.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 123 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
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 per cycle. inspection cycle.
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
[[Page 6800]]
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
The FAA determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify this proposed
regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
0
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
The Boeing Company: Docket No. FAA-2026-1324; Project Identifier AD-
2025-00986-T.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by March 30, 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., ``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:
[email protected]. 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: [email protected].
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (m)(3)
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 myboeingfleet.com.
(4) You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 2200 South 216th St.,
Des
[[Page 6801]]
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 www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].
Issued on February 10, 2026.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft
Certification Service.
[FR Doc. 2026-02912 Filed 2-12-26; 8:45 am]
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