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[Federal Register Volume 90, Number 26 (Monday, February 10, 2025)]
[Rules and Regulations]
[Pages 9209-9211]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-02383]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1467; Project Identifier AD-2023-01241-T; 
Amendment 39-22935; AD 2025-02-02]
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 737-100, -200, -200C, -300, -400, and -500 
series airplanes. This AD was prompted by a report indicating cracks in 
the frame inner chord and web at station (STA) 727. This AD requires an 
inspection for any repair installed, repetitive inspections of the 
frame inner chord and web at STA 727 for any crack, and applicable on-
condition actions. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective March 17, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of March 17, 
2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-1467; 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 Boulevard, 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 Street, 
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-2024-1467.

FOR FURTHER INFORMATION CONTACT: Muoi Vuong, Aviation Safety Engineer, 
FAA, 2200 South 216th Street, Des Moines, WA 98198; telephone: 562-627-
5205; 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 737-100, -200, -200C, -300, -400, and -500 series airplanes. The 
NPRM published in the Federal Register on May 20, 2024 (89 FR 43792). 
The NPRM was prompted by a report indicating cracks in the frame inner 
chord and web at STA 727 between S-11L and S-13L. In the NPRM, the FAA 
proposed to require an inspection for any repair installed, repetitive 
inspections of the frame inner chord and web at STA 727 for any crack, 
and applicable on-condition actions. The FAA is issuing this AD to 
address cracks in the left and right frames at STA 727 before they 
reach a critical length. The unsafe condition, if not addressed, may 
result in the inability of a principal structural element to sustain 
limit load, which could adversely affect the structural integrity of 
the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from three commenters, including Aviation 
Partners Boeing, FlyPersia Airline, and Sudan Civil Aviation Authority. 
In addition, the FAA received a comment from an individual whose 
request is not specific to this AD or a request the FAA can act on. 
This comment is outside the scope of this rulemaking. 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 the installation of winglets 
per the Supplemental Type Certificate (STC) ST01219SE does not affect 
the actions specified in the proposed AD.
    The FAA agrees with the commenter. 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 
ST01219SE does not affect the ability to accomplish the actions 
required by this AD. Therefore, for airplanes on which STC ST01219SE 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 Expand the Area of Inspection

    FlyPersia Airline requested that the area of inspection for any 
repair and repetitive high frequency eddy current inspection include 
the frame inner chord and web at STA 663.75 through STA 727 between 
stringers S-11 and S-13 left and right sides. The commenter stated that 
the mentioned crack on stringers S-11 and S-13 left and right might 
also exist on those stringers at STA 663.75 through STA 727, because on 
Model 737-300 airplanes there is a landing gear cavity, which impresses 
circumferential structure unity on STA 663.75.

[[Page 9210]]

    The FAA disagrees with expanding the area of inspection in this AD. 
The Boeing service bulletin addresses only the frame inner chord and 
web at STA 727, between S-11 and S-13, left and right sides. STA 727 
frame between S-11 and S-13, located at a bulkhead station, is 
different from other frames forward of STA 727, and therefore is the 
only area of inspection addressed in this AD. However, if additional 
data are presented that would justify extending the subject inspection 
area, the FAA might consider further rulemaking on this issue. No 
change has been made to this AD regarding this issue.

Request To Reduce the Proposed Grace Period for the Initial Compliance 
Time

    Sudan Civil Aviation Authority requested the grace period for the 
initial compliance time for the general visual inspection of STA 727 
(within 4,500 flight cycles after the original issue date of the 
requirements bulletin) be reduced. Sudan Civil Aviation Authority 
stated that the compliance time for some Model 737-400 airplanes may 
fall beyond the 50,000 total flight cycles at which the crack has been 
found.
    The FAA disagrees. After considering all the available information, 
the FAA has determined that the grace period, as proposed, represents 
an appropriate interval of time in which the required actions can be 
performed in a timely manner within the affected fleet, while still 
maintaining an adequate level of safety. In developing an appropriate 
grace period, the FAA considered the safety implications, parts 
availability, normal maintenance schedules, and the manufacturer's 
recommendation for timely accomplishment of the modifications. To 
reduce the grace period of the proposed AD would necessitate (under the 
provisions of the Administrative Procedure Act) reissuing the notice, 
reopening the period for public comment, considering additional 
comments subsequently received, and eventually issuing a final rule. In 
light of this, and in consideration of the amount of time that has 
already elapsed since issuance of the original notice, the FAA has 
determined that further delay of this AD is not appropriate. However, 
if additional data are presented that would justify a shorter 
compliance time, the FAA may consider further rulemaking on this issue. 
No change has been made to this AD regarding this issue.

Request To Revise Requirements Bulletin To Delete Condition 2.2

    Sudan Civil Aviation Authority stated that Condition 2.2: No Crack 
Found in Group 2, Table 1: Inspection of Frame at STA 727 Between S-11 
and S-13, Left and Right Side, 3. Compliance, of Boeing Alert 
Requirements Bulletin 737-53A1416RB, dated July 21, 2023, needs to be 
deleted. The commenter pointed out that Condition 2.2 (unrepaired 
areas) should be deleted because there is no repair found.
    The FAA agrees to clarify. Condition 2 is accomplished for 
airplanes that have no repairs in the inspection area and requires high 
frequency eddy current (HFEC) inspections of the area before further 
flight. Condition 2.2 is then accomplished if no crack is found during 
the initial inspection (Condition 2), repeating the HFEC inspections of 
the unrepaired areas within 9,000 flight cycles. Condition 2.2 includes 
footnote (a) because a repair could be installed at any point prior to 
the repeat HFEC inspection, and that repair could terminate the repeat 
HFEC inspection. No change has been made to this AD regarding this 
issue.

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, 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 737-53A1416 RB, 
dated July 21, 2023. This material specifies procedures for a general 
visual inspection for any repair and repetitive high frequency eddy 
current inspections of the frame inner chord and web at STA 727, 
between S-11 and S-13, left and right sides, for any crack, 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 245 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
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                                                                                    Cost per       Cost on U.S.
               Action                        Labor cost           Parts cost        product         operators
----------------------------------------------------------------------------------------------------------------
Inspections.........................  8 work-hours x $85 per               $0             $680         $166,600
                                       hour = $680.
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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:

[[Page 9211]]

    (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:

2025-02-02 The Boeing Company: Amendment 39-22935; Docket No. FAA-
2024-1467; Project Identifier AD-2023-01241-T.

(a) Effective Date

    This airworthiness directive (AD) is effective March 17, 2025.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to all The Boeing Company Model 737-100, -
200, -200C, -300, -400, and -500 series airplanes, certificated in 
any category.
    (2) Installation of Supplemental Type Certificate (STC) 
ST01219SE does not affect the ability to accomplish the actions 
required by this AD. Therefore, for airplanes on which STC ST01219SE 
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 indicating cracks in the frame 
inner chord and web at station (STA) 727. The FAA is issuing this AD 
to address cracks in the left and right frames at STA 727 before 
they reach a critical length. The unsafe condition, if not 
addressed, may result in the inability of a principal structural 
element to sustain limit load, which could adversely affect the 
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 Requirements 
Bulletin 737-53A1416 RB, dated July 21, 2023: Within 120 days after 
the effective date of this AD, inspect for existing repairs and 
cracking of the frame inner chord and web at STA 727, between S-11 
and S-13, left and right sides, using a method approved in 
accordance with the procedures specified in paragraph (j) of this 
AD.

(h) Required Actions for Group 2 Airplanes

    For airplanes identified as Group 2 in Boeing Alert Requirements 
Bulletin 737-53A1416 RB, dated July 21, 2023: Except as specified by 
paragraph (i) of this AD, at the applicable times specified in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
53A1416 RB, dated July 21, 2023, do all applicable actions 
identified in, and in accordance with, the Accomplishment 
Instructions of Boeing Alert Requirements Bulletin 737-53A1416 RB, 
dated July 21, 2023.
    Note 1 to paragraph (h): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Service Bulletin 737-
53A1416, dated July 21, 2023, which is referred to in Boeing Alert 
Requirements Bulletin 737-53A1416 RB, dated July 21, 2023.

(i) Exceptions to Requirements Bulletin Specifications

    (1) Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
53A1416 RB, dated July 21, 2023, refers to the original issue date 
of Boeing Alert Requirements Bulletin 737-53A1416 RB, this AD 
requires using the effective date of this AD.
    (2) Where Boeing Alert Requirements Bulletin 737-53A1416 RB, 
dated July 21, 2023, specifies contacting Boeing for repair 
instructions or for alternative inspections, this AD requires doing 
the repair, or doing the alternative inspections and applicable on-
condition actions, before further flight using a method approved in 
accordance with the procedures specified in paragraph (j) of this 
AD.

(j) Alternative Methods of Compliance

    (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 
(k)(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.

(k) Related Information

    (1) For more information about this AD, contact Muoi Vuong, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; telephone: 562-627-5205; email: [email protected].
    (2) Material identified in this AD that is not incorporated by 
reference is available at the address specified in paragraph (l)(3) 
of this AD.

(l) 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 737-53A1416 RB, dated 
July 21, 2023.
    (ii) [Reserved]
    (3) For Boeing material identified in this AD, contact Boeing 
Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 
2600 Westminster Boulevard, 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 
Street, 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 January 14, 2025.
Suzanne Masterson,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2025-02383 Filed 2-7-25; 8:45 am]
BILLING CODE 4910-13-P
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