[4910-13-P]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2024-1880; Project Identifier AD-2023-01149-T]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) for all The
Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes.
This proposed AD was prompted by a report of a frame web crack at fuselage station
(STA) 328 between stringers S-20R and S-21R common to the frame web notch. This
proposed AD would require repetitive detailed inspections of the forward and aft sides of
the frames and high frequency eddy current (HFEC) inspections of the frames for cracks
and repairing any crack found. 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 [INSERT DATE 45
DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
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. FAA2024-1880; 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 NPRM, any
comments received, and other information. The street address for Docket Operations is
listed above.
Material Incorporated by Reference:
• For service information, 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 service information 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-2024-1880.
FOR FURTHER INFORMATION CONTACT: Bill Ashforth, Aviation Safety
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 206-231-3520;
email: bill.ashforth@faa.gov.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or arguments about
this proposal. Send your comments to an address listed under ADDRESSES. Include
“Docket No. FAA-2024-1880; Project Identifier AD-2023-01149-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 Bill Ashforth,
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198;
phone: 206-231-3520; email: bill.ashforth@faa.gov. 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 that an operator of a Model 737-700 airplane
found a frame web crack at fuselage STA 328 between stringers S-20R and S-21R while

performing a visual inspection of the electrical and electronics compartment during
scheduled maintenance. The crack was common to the frame web notch and was
approximately 0.85 inch long. The crack originated at a notch radius of the lower frame
web that is subject to a load transfer from the inner chord of the upper frame. 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 affected. Model 737-600, -700C, -800, -900, and 900ER series airplanes have similar structure in the affected area and are also subject to
this unsafe condition. Undetected cracks in the frame 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.
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.
Related Service Information under 1 CFR Part 51
The FAA reviewed Boeing Alert Requirements Bulletin 737-53A1410 RB, dated
October 11, 2023. This service information 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 S22R, and STA 344 from S-20R to S-23R for cracks. This service information also
specifies repairing any crack found.
This service information is reasonably available because the interested parties
have access to it through their normal course of business or by the means identified in
ADDRESSES.

Proposed AD Requirements in this NPRM
This proposed AD would require accomplishing the actions specified in the
service information already described, 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 service information at regulations.gov under Docket No. FAA2024-1880.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would affect 1,583
airplanes of U.S. registry. The FAA estimates the following costs to comply with this
proposed AD:
Estimated costs
Action

Labor cost

Parts cost

Cost per
product

Cost on U.S.
operators

Inspections

9 work-hours X $85
per hour = $765 per
inspection cycle

$0

$765 per
inspection
cycle

$1,210,995
per inspection
cycle

Estimated costs of on-condition actions
The extent of damage/cracking found during the proposed 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.
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
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
§ 39.13 [Amended]
2. The FAA amends § 39.13 by adding the following new airworthiness directive:

The Boeing Company: Docket No. FAA-2024-1880; Project Identifier AD-2023-01149T.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive (AD) by
[INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL
REGISTER].
(b) Affected ADs
None.
(c) Applicability
This AD applies to all The Boeing Company (Boeing) Model 737-600, -700,
-700C, -800, -900, and -900ER series airplanes, certificated in any category.
(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 Service Information 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:
AMOC@faa.gov.
(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 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 Bill Ashforth, Aviation Safety
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 206-231-3520;
email: bill.ashforth@faa.gov.
(2) Service information 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 service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part
51.
(2) You must use this service information 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 service information, 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 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
fr.inspection@nara.gov.
Issued on June 26, 2024.

Suzanne Masterson,
Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2024-14521 Filed: 7/1/2024 8:45 am; Publication Date: 7/2/2024]