Airworthiness Directives; The Boeing Company Airplanes

[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 [www.gpo.gov]
[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 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 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 myboeingfleet.com.
    <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 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:

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
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Repetitive inspections...........  7 work-hours x $85               $0  $595 per inspection  $73,185 per
                                    per hour = $595                      cycle.               inspection cycle.
                                    per inspection
                                    cycle.
----------------------------------------------------------------------------------------------------------------

    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: 
[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) 
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 myboeingfleet.com.
    (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 www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    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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