[Federal Register Volume 90, Number 137 (Monday, July 21, 2025)]
[Rules and Regulations]
[Pages 34171-34173]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-13595]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2024-1880; Project Identifier AD-2023-01149-T;
Amendment 39-23088; AD 2025-15-01]
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 all
The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER
series airplanes. This AD was prompted by a report of a frame web crack
at a certain fuselage station (STA) between certain stringers common to
the frame web notch. This AD requires repetitive inspections for cracks
of the frames and repair of cracks. The FAA is issuing this AD to
address the unsafe condition on these products.
DATES: This AD is effective August 25, 2025.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of August 25,
2025.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-1880; 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:
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.
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-2024-1880.
FOR FURTHER INFORMATION CONTACT: Owen Bley-Male, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3992; 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 all The Boeing Company
Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes.
The NPRM published in the Federal Register on July 2, 2024 (89 FR
54737). The NPRM was prompted by a report of a frame web crack at
fuselage STA 328 between stringers S-20R and S-21R on a Model 737-700
airplane. The crack was common to the frame web notch and was
approximately 0.85 inch long. In the NPRM, the FAA proposed to require
repetitive detailed and high frequency eddy current (HFEC) inspections
for cracks of the frames and repair of any cracks. The FAA is issuing
this AD to address undetected cracks in the frame, which could lead to
the inability of the principal structural element to sustain limit
loads and result in the subsequent loss of structural integrity of the
airplane.
Discussion of Final Airworthiness Directive
Comments
The FAA received a comment from United Airlines, which supported
the NPRM without change.
The FAA also received comments from Aviation Partners Boeing, The
Boeing Company (Boeing), Southwest Airlines (Southwest), and Sudan
Civil Aviation Authority (Sudan CAA). The following presents the
comments received on the NPRM and the FAA's response to each comment.
Effect of Winglets on Accomplishment of the Proposed Actions
Aviation Partners Boeing stated that installing winglets under
Supplemental Type Certificate (STC) ST00830SE does not affect
accomplishment of the actions specified in the proposed AD.
The FAA agrees. The FAA has redesignated paragraph (c) of the
proposed AD as paragraph (c)(1) of this AD and added paragraph (c)(2)
to this AD to state that installation of STC ST00830SE does not affect
the ability to accomplish the actions required by this AD. Therefore,
for airplanes on which STC ST00830SE is installed, a ``change in
product'' alternative method of compliance (AMOC) approval request is
not necessary to comply with the requirements of 14 CFR 39.17.
Request To Revise Stringer Range
Boeing requested the FAA clarify the preamble with respect to the
stringer range for each affected frame. Boeing noted that the
Background section of the NPRM identifies the affected area as ``STA
312, STA 328, and STA 344 from stringers S-20R to S-23R.'' Boeing
requested that the text specify the stringer range for each frame and
be changed to ``STA 312 (Stringers S-20R to S-23R), STA 328 (Stringers
S-19R to S-22R), and STA 344 (Stringers S-20R to S-23R).''
The FAA agrees that the requested change would clarify the affected
area. However, as this information from the NPRM is not restated in
this final rule, no change is necessary as a result of this comment.
Requests Regarding Frame Replacement
Southwest requested the FAA change the proposed AD to allow
replacement of a cracked frame with a new frame as an option instead of
repairing the frame. Southwest further requested that, for frames
replaced with a new frame, the FAA allow the compliance time to start
from the date of the new frame installation. Southwest stated that this
adjusted threshold is similar to the principle structural element
replacement guidance in the FAA-approved airworthiness limitations for
the affected model airplanes.
The FAA acknowledges that removal and replacement with type design
parts is possible but does not agree to include this option in
paragraph (h)(2) of this AD or adjust the compliance time for allowing
this replacement as a repair without complete substantiating data.
Replacement might involve oversizing holes, replacing more than just
the frame, or other actions that would
[[Page 34172]]
impact the appropriate compliance time, including requiring shorter
inspection intervals. Each replacement would involve unique
circumstances, so the FAA cannot determine whether allowing the
compliance time to start from the date of the new frame installation
would provide an adequate level of safety. Therefore, the FAA has not
changed the AD in this regard. The FAA will, however, consider AMOCs in
accordance with paragraph (i) of this AD for alternative repair actions
or compliance time changes, provided substantiation data is submitted
to show that an acceptable level of safety is maintained using the
alternative actions and compliance times.
Request To Expand Inspection Areas
Sudan CAA requested that the inspection areas for each station be
expanded beyond the stringers specified in Boeing Alert Requirements
Bulletin 737-53A1410 RB, dated October 11, 2023. Sudan CAA stated that
typical cracks in the frame start at the blanket pin hole, the fastener
in the inner chord, or the frame web notch, and cracking could occur at
adjacent areas that are not covered by the service information. Sudan
CAA therefore concluded that the proposed AD may not address the unsafe
condition.
The FAA disagrees with this request. The inspection area is
determined for each frame by the design and loading of the frame, which
are similar, but not identical, across the three frames. This AD was
prompted by a frame web crack at fuselage STA 328 between stringers S-
20R and S-21R. Because the load transfer is similar in adjacent areas,
the frames at STA 312, STA 328, and STA 344 from stringers S-20R to S-
23R are also subject to the unsafe condition. Based on the fleet data
the FAA has received, the FAA determined that the actions specified in
the referenced service information adequately address the unsafe
condition. Therefore, the FAA has not changed this AD as a result of
this comment. If new information becomes available, the FAA might
consider further rulemaking.
Request To Revise Applicability
Boeing requested that the FAA revise the applicability to only
include line numbers 1 through 9273. Boeing stated that line numbers
9274 and subsequent will have a new design change in notch radius
(0.25'' changed from 0.16'') that will mitigate the safety issue.
Boeing further stated it will revise its service information to reflect
this change in effectivity.
The FAA does not agree to reduce the applicability of this AD.
Boeing is still in the process of having the design change approved. In
addition, once approved, the FAA will need to determine whether the
design change adequately addresses the unsafe condition. Should the FAA
determine the design change provides an acceptable level of safety to
address the unsafe condition, operators may request approval of the
design change as an AMOC using the procedures in paragraph (i) of this
AD.
Request To Correct Typographical Error
Sudan CAA requested a revision to note (b) of Figure 1 in Boeing
Alert Requirements Bulletin 737-53A1410 RB, dated October 11, 2023,
which refers to a certain structural detail that ``is inspected.''
Sudan CAA requested replacing ``is inspected'' with ``is to be
inspected'' for clarification.
The FAA does not find the requested change necessary. The FAA
reviewed the requirements bulletin and determined that it provides
sufficient clarity.
Conclusion
The FAA reviewed the relevant data, considered the 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, and
any other changes described previously, 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 737-53A1410 RB,
dated October 11, 2023. This material specifies procedures for
repetitive detailed inspections of the forward and aft sides of the
frames, and surface and open hole HFEC inspections of the frames, at
STA 312 from S-20R to S-23R, STA 328 from S-19R to S-22R, and STA 344
from S-20R to S-23R for cracks. This material also specifies repairing
any crack 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 1,583 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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Inspections...................... 9 work-hours x $85 $0 $765 per inspection $1,210,995 per
per hour = $765 cycle. inspection cycle.
per inspection
cycle.
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Estimated Costs of On-Condition Actions
The extent of damage/cracking found during the required inspections
could vary significantly from airplane to airplane. The FAA has no way
of determining the type of repair or cost to repair any cracks on each
airplane or the number of airplanes that may require repair.
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.
[[Page 34173]]
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(f), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
2025-15-01 The Boeing Company: Amendment 39-23088; Docket No. FAA-
2024-1880; Project Identifier AD-2023-01149-T.
(a) Effective Date
This airworthiness directive (AD) is effective August 25, 2025.
(b) Affected ADs
None.
(c) Applicability
(1) This AD applies to all The Boeing Company Model 737-600, -
700, -700C, -800, -900, and -900ER series airplanes, certificated in
any category.
(2) Installation of Supplemental Type Certificate (STC)
ST00830SE does not affect the ability to accomplish the actions
required by this AD. Therefore, for airplanes on which STC ST00830SE
is installed, a ``change in product'' alternative method of
compliance (AMOC) approval request is not necessary to comply with
the requirements of 14 CFR 39.17.
(d) Subject
Air Transport Association (ATA) of America Code 53, Fuselage.
(e) Unsafe Condition
This AD was prompted by a report of a frame web crack at
fuselage station 328 between stringers S-20R and S-21R common to the
frame web notch. The FAA is issuing this AD to address undetected
cracks in the frame. The unsafe condition, if not addressed, could
lead to the inability of the principal structural element to sustain
limit loads, which could result in the subsequent loss of structural
integrity of the airplane.
(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 737-53A1410 RB, dated October 11, 2023,
do all applicable actions identified in, and in accordance with, the
Accomplishment Instructions of Boeing Alert Requirements Bulletin
737-53A1410 RB, dated October 11, 2023.
Note 1 to paragraph (g): Guidance for accomplishing the actions
required by this AD can be found in Boeing Alert Service Bulletin
737-53A1410, dated October 11, 2023, which is referred to in Boeing
Alert Requirements Bulletin 737-53A1410 RB, dated October 11, 2023.
(h) Exceptions to Requirements Bulletin Specifications
(1) Where the ``Boeing Recommended Compliance Time'' column in
the table under the ``Compliance'' paragraph of Boeing Alert
Requirements Bulletin 737-53A1410 RB, dated October 11, 2023, refers
to ``the Original Issue date of Requirements Bulletin 737-53A1410
RB,'' this AD requires using the effective date of this AD.
(2) Where Boeing Alert Requirements Bulletin 737-53A1410 RB,
dated October 11, 2023, specifies contacting Boeing for repair
instructions, this AD requires doing the repair using a method
approved in accordance with the procedures in paragraph (i) of this
AD.
(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 certification office,
send it to the attention of the person identified in paragraph
(j)(1) 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 responsible Flight Standards 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, 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) Related Information
(1) For more information about this AD, contact Owen Bley-Male,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 206-231-3992; email: [email protected].
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (k)(3)
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 737-53A1410 RB, dated
October 11, 2023.
(ii) [Reserved]
(3) For the 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 July 16, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft
Certification Service.
[FR Doc. 2025-13595 Filed 7-18-25; 8:45 am]
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