[Federal Register Volume 89, Number 75 (Wednesday, April 17, 2024)]
[Rules and Regulations]
[Pages 27376-27379]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-08104]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1413; Project Identifier AD-2023-00087-T; 
Amendment 39-22706; AD 2024-06-01]
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 
certain The Boeing Company Model 737-600, -700, -700C, -800, -900 and -
900ER airplanes. This AD was prompted by reports of cracks in the 
forward galley door cutout forward upper corner bear strap. It has been 
determined that the cracks were caused by high operating stresses in 
the fuselage skin door cutout corner area due to stress concentration 
at the door cutout. This AD requires an inspection of the fuselage skin 
and the bear strap at the forward galley door cutout forward upper 
corner for existing repairs, and applicable related investigative and 
corrective actions. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective May 22, 2024.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of May 22, 
2024.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2023-1413; 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 service information identified in this final rule, 
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 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-2023-1413.

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 certain The Boeing 
Company Model 737-600, -700, -700C, -800, -900 and -900ER airplanes. 
The NPRM published in the Federal Register on July 24, 2023 (88 FR 
47399). The NPRM was prompted by reports of cracks in the forward 
galley door cutout forward upper corner bear strap. In the NPRM, the 
FAA proposed to require an inspection of the fuselage skin and the bear 
strap at the forward galley door cutout forward upper corner for 
existing repairs, and applicable related investigative and corrective 
actions. The FAA is issuing this AD to address cracks in the fuselage 
skin and bear strap, which could increase in length until the fuselage 
skin and bear strap severs. If not detected and corrected, a severed 
fuselage skin and bear strap may lead to the inability of the principal 
structural element (PSE) to sustain limit loads and may result in rapid 
decompression of the fuselage and loss of structural integrity.

[[Page 27377]]

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from seven commenters, including Boeing, 
Aviation Partners Boeing, Delta Air Lines (Delta), Southwest Airlines 
(Southwest), Sun Country Airlines (SCA), Sideral Linhas Aereas 
(Sideral), and United Airlines (United). 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 Supplemental Type Certificate (STC) ST00830SE does not affect the 
actions specified in the proposed AD.
    The FAA concurs 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 
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 Clarify Related Investigative Actions

    Boeing requested that the FAA revise the Related Service 
Information Under 1 CFR part 51 portion of the NPRM to specify that 
related investigative actions include external and internal eddy 
current inspections, as well as detailed inspections, as specified in 
Boeing Alert Requirements Bulletin 737-53A1407 RB, dated December 20, 
2022.
    The FAA agrees for the reasons provided and has revised the Related 
Service Information Under 1 CFR part 51 portion of this final rule 
accordingly.

Request To Allow Later-Approved Versions of a Structural Repair Manual 
(SRM)

    Delta, Southwest, Sideral, and United requested that the proposed 
AD be revised to allow later-approved revisions of 737NG SRM 53-10-01 
Repair 6. United noted that existing repairs are evaluated against 
737NG SRM 53-10-01 Repair 6, dated March 10, 2020, to determine 
appropriate corrective actions. Delta claimed that, as written, only 
737NG SRM 53-10-01 Repair 6, dated March 10, 2020, is an approved 
previous repair in the service information. Southwest, Sideral, and 
United all noted that the SRM may get updated and older copies of the 
SRM are not made available to technicians, which may lead to confusion 
and delays. United and Sideral added that repairs made using a future 
version of the SRM may not match the current version, which would 
require operators to obtain an AMOC.
    The FAA agrees for the reasons provided. The FAA has added 
paragraph (h)(3) of this AD to include later-approved revisions of 
737NG SRM 53-10-01 Repair 6, dated March 10, 2020.

Request To Allow Applying a Certain Repair in Lieu of Obtaining 
Instructions

    Delta requested that the proposed AD be revised to allow applying 
737NG SRM 53-10-01 Repair 6 and following the limitations of Table 3 of 
Boeing Alert Requirements Bulletin 737-53A1407 RB, dated December 20, 
2022, in lieu of contacting Boeing or the FAA for repair instructions 
and doing that repair when an airplane is in Condition 2.1 or Condition 
4.1, as specified in in Boeing Alert Requirements Bulletin 737-53A1407 
RB, dated December 20, 2022. Delta stated that the service information 
allows retaining 737NG SRM 53-10-01 Repair 6 if it is already applied 
on an airplane and does not require removal of that repair. Delta added 
that if an airplane is in an overnight or short visit, the option of 
installing 737NG SRM 53-10-01 Repair 6 is faster and would only appear 
to require additional inspections within 24,000 flight cycles.
    The FAA disagrees with the commenter's request. Each crack 
configuration found when accomplishing this AD will be unique and will 
require an analysis to determine the appropriate repair and post-repair 
inspection protocol. Boeing 737NG SRM 53-10-01 Repair 6 is designed for 
a certain crack configuration, and therefore will not be applicable to 
every crack that might be found when complying with this AD. However, 
an operator may request an AMOC following the procedures in paragraph 
(i) of this AD to use a different repair method.

Request for Creation of a Preventative Modification

    SCA requested that a preventative modification be developed that 
could terminate the repetitive inspections specified in Boeing Alert 
Requirements Bulletin 737-53A1407 RB, dated December 20, 2022. SCA 
added that the proposed AD affects all Boeing 737NG airplanes, but the 
repair referenced in Boeing Alert Requirements Bulletin 737-53A1407 RB, 
dated December 20, 2022, is only effective for a small portion of the 
fleet.
    The FAA disagrees with the commenter's request. After analyzing the 
relevant data, the FAA has determined that the repetitive inspections 
specified in the service information required by this AD are adequate 
to address the unsafe condition. Additionally, the FAA infers that the 
repair method the commenter referred to is 737NG SRM 53-10-01 Repair 6. 
The FAA notes that the service information has conditions related to 
whether or not a repair was accomplished using 737NG SRM 53-10-01 
Repair 6, but requires operators to obtain and follow instructions for 
new crack findings, which is a method applicable to all airplanes.

Request To Combine Actions With Another AD

    SCA requested that the inspections in the proposed AD be combined 
with the inspections in AD 2021-02-13, Amendment 39-21396 (86 FR 10776, 
February 23, 2021) (AD 2021-02-13). The commenter stated that the 
proposed AD's inspection area is in immediate proximity of the 
inspection area required by AD 2021-02-13, and corrective actions for a 
finding in either inspection area will affect the inspection 
requirements for both the proposed AD and AD 2021-02-13. SCA claimed 
this would require obtaining two AMOCs for a single finding, adding 
undue complexity. The commenter also noted that, while both the 
proposed AD and AD 2021-02-13 require contacting the manufacturer, 
there is a strong potential for oversight regarding compliance with the 
proposed AD or AD 2021-02-13. SCA stated that, at a minimum, AD 2021-
02-13 should be listed as an affected AD in paragraph (b) of the 
proposed AD, since an external reinforcing repair would affect the 
inspection of both the proposed AD and AD 2021-02-13.
    The FAA disagrees with the commenter's request. Although the two 
ADs require actions in areas that are in close proximity (AD 2021-02-13 
requires inspections for cracks of the fuselage skin and bear strap at 
the forward galley door between certain stations, and applicable on-
condition actions), they require different actions to address different 
unsafe conditions. Therefore, combining the two ADs would not be 
practical. Additionally, only ADs that are superseded or terminated by 
another AD are considered ``affected'' ADs. Finally, if an operator 
needs to request a repair

[[Page 27378]]

that affects both this AD and AD 2021-02-13, they may request a single 
AMOC.

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.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 737-53A1407 RB, 
dated December 20, 2022. This service information specifies procedures 
for an external general visual inspection of the fuselage skin at the 
forward galley door cutout forward upper corner for any repair, and 
applicable related investigative and corrective actions. Related 
investigative actions include detailed inspections for cracking of the 
fuselage skin and bear strap; and internal and external high frequency 
eddy current (HFEC) and low frequency eddy current (LFEC) inspections 
for cracking of the fuselage skin, bear strap, and repair parts. 
Corrective actions include obtaining and following instructions for 
crack repair. 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.

Costs of Compliance

    The FAA estimates that this AD affects 1,938 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
----------------------------------------------------------------------------------------------------------------
External general visual            0.5 work-hour x $85              $0  $42.50 per           $82,365 per
 inspection for repairs.            per hour = $42.50                    inspection cycle.    inspection cycle.
                                    per inspection
                                    cycle.
External detailed and eddy         3.5 work-hours x                  0  $197.50............  $576,555.
 current inspection for cracks.     $85 per hour =
                                    $197.50.
External eddy current inspection   4 work-hours x $85                0  $340 per inspection  Up to $658,920 per
 without a quadrupler repair.       per hour = $340                      cycle.               inspection cycle.
                                    per inspection
                                    cycle.
External eddy current inspection   4 work-hours x $85                0  $340 per inspection  Up to $658,920 per
 with a quadrupler repair.          per hour = $340                      cycle.               inspection cycle.
                                    per inspection
                                    cycle.
Internal eddy current inspection   26 work-hours x $85               0  $2,210.............  $4,282,980.
 for cracks.                        per hour = $2,210.
----------------------------------------------------------------------------------------------------------------

    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition repairs or for the alternative 
inspections 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:

2024-06-01 The Boeing Company: Amendment 39-22706; Docket No. FAA-
2023-1413; Project Identifier AD-2023-00087-T.

(a) Effective Date

    This airworthiness directive (AD) is effective May 22, 2024.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900 and -900ER airplanes, certificated in any category, 
as identified in Boeing Alert Requirements Bulletin 737-53A1407 RB, 
dated December 20, 2022.
    (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

[[Page 27379]]

(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 reports of cracks in the forward galley 
door cutout forward upper corner bear strap. The FAA is issuing this 
AD to address cracks in the fuselage skin and bear strap, which 
could increase in length until the fuselage skin and bear strap 
severs. If not detected and corrected, a severed fuselage skin and 
bear strap may lead to the inability of the principal structural 
element (PSE) to sustain limit loads and may result in rapid 
decompression of the fuselage and loss of structural integrity.

(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 737-53A1407 RB, dated December 20, 2022, 
do all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-53A1407 RB, dated December 20, 2022.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-53A1407, dated December 20, 2022, which is referred to in Boeing 
Alert Requirements Bulletin 737-53A1407 RB, dated December 20, 2022.

(h) Exceptions to Service Information Specifications

    (1) Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
53A1407 RB, dated December 20, 2022, refer to the original issue 
date of Requirements Bulletin 737-53A1407 RB, this AD requires using 
the effective date of this AD.
    (2) Where Boeing Alert Requirements Bulletin 737-53A1407 RB, 
dated December 20, 2022, 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, using a method approved in accordance with the 
procedures specified in paragraph (i) of this AD.
    (3) Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph and the Condition columns and flag notes of 
the tables in the ``Compliance'' and ``Accomplishment Instructions'' 
paragraphs of Boeing Alert Requirements Bulletin 737-53A1407 RB, 
dated December 20, 2022, use the phrase ``737NG SRM 53-10-01 REPAIR 
6 DATED MARCH 10, 2020,'' this AD requires replacing that text with 
``737NG SRM 53-10-01 Repair 6 dated March 10, 2020, or later-
approved versions.''

(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) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraph (k)(3) of this AD

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) 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 737-53A1407 RB, dated 
December 20, 2022.
    (ii) [Reserved]
    (3) For service information 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 service information 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 March 12, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-08104 Filed 4-16-24; 8:45 am]
BILLING CODE 4910-13-P