[Federal Register Volume 87, Number 185 (Monday, September 26, 2022)]
[Rules and Regulations]
[Pages 58257-58259]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-20736]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0093; Project Identifier AD-2021-00987-T; 
Amendment 39-22164; AD 2022-18-13]
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, and -900 
series airplanes. This AD was prompted by an evaluation by the design 
approval holder (DAH) indicating that certain web lap splices in the 
center dome apex of the aft pressure bulkhead are subject to widespread 
fatigue damage (WFD). This AD requires a general visual inspection for 
existing repairs at the aft pressure bulkhead; repetitive detailed, 
high frequency eddy current (HFEC), and low frequency eddy current 
(LFEC) inspections; and repair if necessary. The FAA is issuing this AD 
to address the unsafe condition on these products.

DATES: This AD is effective October 31, 2022.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 31, 
2022.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2022-0093; 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; internet 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-2022-0093.

FOR FURTHER INFORMATION CONTACT: Bill Ashforth, Aerospace Engineer, 
Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3520; 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, and -900 series airplanes. 
The NPRM published in the Federal Register on February 25, 2022 (87 FR 
10755). The NPRM was prompted by an evaluation by the DAH indicating 
that certain web lap splices in the center dome apex of the aft 
pressure bulkhead are subject to WFD. In the NPRM, the FAA proposed to 
require a general visual inspection for existing repairs at the aft 
pressure bulkhead; repetitive detailed, HFEC, and LFEC inspections; and 
repair if necessary. The FAA is issuing this AD to address fatigue 
cracks in the webs of the aft pressure bulkhead, which could result in 
reduced structural integrity of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from United Airlines and two individuals, 
who supported the NPRM without change.
    The FAA received additional comments from Southwest Airlines (SWA), 
Boeing, and Aviation Partners Boeing. The following presents the 
comments received on the NPRM and the FAA's response to each comment.

Effects of Winglets on Accomplishment of the Proposed Actions

    Aviation Partners Boeing stated that accomplishing 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

[[Page 58258]]

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 Cause of Unsafe Condition

    Boeing requested that the FAA revise the SUMMARY of the NPRM and 
paragraph (e) of the proposed AD. Boeing noted that the SUMMARY of the 
NPRM and paragraph (e) of the proposed AD refer to WFD, but Boeing 
contends that the unsafe condition was caused by pull up on the first 
two fasteners at the web lap splices in the center dome apex. Boeing 
explained that these fasteners, which are located adjacent to the area 
where the aft web transitions over the forward web in the lap splice, 
are subject to clamp-up stresses (which are pre-stresses during the 
assembly). These stresses, combined with pressurization, will reduce 
the fatigue life of the web at the center dome apex and potentially 
cause early cracking in this location.
    The FAA partially agrees. The FAA agrees with Boeing that the 
unsafe condition was discovered through clamp-up stresses, as well as 
other non-WFD events. The WFD evaluation revealed that the area is 
susceptible to WFD; as a result, this unsafe condition is related to 
WFD. Therefore, the FAA maintains that the SUMMARY of this final rule 
and paragraph (e) of this AD are correct in stating that the affected 
areas are subject to WFD. The FAA has not changed this AD in this 
regard.

Request for Clarification for Repairs Found in the Aft Pressure 
Bulkhead

    SWA requested clarification regarding paragraph (h)(2) of the 
proposed AD. SWA noted that in Table 1 of paragraph 3., Compliance, of 
Boeing Alert Requirements Bulletin 737-53A1403 RB, dated August 26, 
2021, CONDITION 1 (ACTION 1) specifies to contact Boeing for any repair 
found during the general visual inspection of the aft pressure 
bulkhead. CONDITION 1 (ACTION 1) also references flag note (a), which 
states:

    CONDITION 1 (ACTION 1) is not required for any repair found 
during the General Visual Inspection of the APB [aft pressure 
bulkhead] aft side in areas where a repair covers the affected 
inspection zones provided that the installed repair was approved by 
The Boeing Company Organization Designation Authorization (ODA) via 
a FAA Form 8100-9 and inspections are accomplished in accordance 
with the scheduled repair approval listed on the FAA Form 8100-9.

    SWA stated that its interpretation is that paragraph (h)(2) of the 
proposed AD applies to all repairs found where the operator must 
contact Boeing due to the repair not meeting the criteria listed in 
flag note (a). SWA went on to observe that if the repairs found during 
CONDITION 1 (ACTION 1) meet the requirements of flag note (a), then the 
operator is not required to contact Boeing.
    The FAA provides the following clarification. SWA is correct in its 
interpretation that paragraph (h)(2) of this AD applies to all 
instances where the operator must contact Boeing for repair 
instructions or for alternative inspections. If the repairs found 
during the general visual inspection of the aft pressure bulkhead aft 
side meet the requirements of flag note (a) of Table 1 of paragraph 3., 
Compliance, of Boeing Alert Requirements Bulletin 737-53A1403 RB, dated 
August 26, 2021, then contacting Boeing is not required. The FAA has 
not changed this AD in this regard.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. 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 737-53A1403 RB, 
dated August 26, 2021. This service information specifies procedures 
for a general visual inspection for existing repairs at the aft 
pressure bulkhead; repetitive detailed, HFEC, and LFEC inspections for 
any crack; and repair of cracks if necessary. 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 1,187 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
----------------------------------------------------------------------------------------------------------------
Inspection for repairs............  1 work-hour x $85             $0  $85.................  $100,895.
                                     per hour = $85.
Repetitive detailed, HFEC, and      Up to 9 work-hours x           0  Up to $765 per        Up to $908,055 per
 LFEC inspections.                   $85 per hour = Up                 inspection cycle.     inspection cycle.
                                     to $765 per
                                     inspection cycle.
----------------------------------------------------------------------------------------------------------------

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

[[Page 58259]]

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:

2022-18-13 The Boeing Company: Amendment 39-22164; Docket No. FAA-
2022-0093; Project Identifier AD-2021-00987-T.

(a) Effective Date

    This airworthiness directive (AD) is effective October 31, 2022.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, and -900 series airplanes, certificated in any category, 
as identified in Boeing Alert Requirements Bulletin 737-53A1403 RB, 
dated August 26, 2021.
    (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 an evaluation by the design approval 
holder (DAH) indicating that certain web lap splices in the center 
dome apex of the aft pressure bulkhead are subject to widespread 
fatigue damage (WFD). The FAA is issuing this AD to address fatigue 
cracks in the webs of the aft pressure bulkhead, which could result 
in reduced 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 737-53A1403 RB, dated August 26, 2021, 
do all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-53A1403 RB, dated August 26, 2021.

    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-53A1403, dated August 26, 2021, which is referred to in Boeing 
Alert Requirements Bulletin 737-53A1403 RB, dated August 26, 2021.

(h) Exceptions to Service Information Specifications

    (1) Where the Compliance Time column of the table in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
53A1403 RB, dated August 26, 2021, uses the phrase ``the original 
issue date of the Requirements Bulletin 737-53A1403 RB,'' this AD 
requires using ``the effective date of this AD.''
    (2) Where Boeing Alert Requirements Bulletin 737-53A1403 RB, 
dated August 26, 2021, 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.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO 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) 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, Seattle 
ACO 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

    For more information about this AD, contact Bill Ashforth, 
Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 
South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3520; 
email: [email protected].

(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 737-53A1403 RB, dated 
August 26, 2021.
    (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; internet 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 service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, [email protected], or go to: archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on August 24, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-20736 Filed 9-23-22; 8:45 am]
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