[Federal Register Volume 87, Number 216 (Wednesday, November 9, 2022)]
[Proposed Rules]
[Pages 67581-67584]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-24244]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1250; Project Identifier AD-2022-00763-T]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Model Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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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 an evaluation 
by the design approval holder (DAH) indicating that the skin lap splice 
at certain stringers is subject to widespread fatigue damage (WFD). 
This proposed AD would require an inspection for any repair at certain 
skin lap splices and depending on the configuration, repetitive 
inspections for buckling, wrinkling, bulging at affected skin lap 
splices and repair, repetitive inspections for cracking at affected 
locations common to fuselage skin on the left and right sides and 
repair, and alternative inspections and on-condition actions. 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 December 
27, 2022.

ADDRESSES: You may send comments, using the procedures found in 14 CFR

[[Page 67582]]

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.
    For service information identified in this NPRM, 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 
referenced 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 by searching 
for and locating Docket No. FAA-2022-1250.

Examining the AD Docket

    You may examine the AD docket at regulations.gov by searching for 
and locating Docket No. FAA-2022-1250; 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.

FOR FURTHER INFORMATION CONTACT: Willard Ashforth, Senior Aerospace 
Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th 
St., Des Moines, WA 98198; phone: 206-231-3520; email: 
[email protected].

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-2022-1250; Project Identifier 
AD-2022-00763-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 
Willard Ashforth, Senior Aerospace Engineer, Airframe Section, FAA, 
Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone: 
206-231-3520; email: [email protected]. A. Any commentary that the 
FAA receives that is not specifically designated as CBI will be placed 
in the public docket for this rulemaking.

Background

    Fatigue damage can occur locally, in small areas or structural 
design details, or globally, in widespread areas. Multiple-site damage 
is widespread damage that occurs in a large structural element such as 
a single rivet line of a lap splice joining two large skin panels. 
Widespread damage can also occur in multiple elements such as adjacent 
frames or stringers. Multiple-site damage and multiple-element damage 
cracks are typically too small initially to be reliably detected with 
normal inspection methods. Without intervention, these cracks will 
grow, and eventually compromise the structural integrity of the 
airplane. This condition is known as WFD. It is associated with general 
degradation of large areas of structure with similar structural details 
and stress levels. As an airplane ages, WFD will likely occur, and will 
certainly occur if the airplane is operated long enough without any 
intervention.
    An FAA final rule (``Aging Airplane Program: Widespread Fatigue 
Damage;'' 75 FR 69746, November 15, 2010) became effective on January 
14, 2011, and amended 14 CFR parts 25, 26, 121, and 129 (commonly known 
as the WFD rule). The WFD rule requires certain actions to prevent 
structural failure due to WFD throughout the operational life of 
certain existing transport category airplanes and all of these 
airplanes that will be certificated in the future. Design approval 
holders (DAHs) of existing and future airplanes subject to the WFD rule 
are required to establish a limit of validity (LOV) of the engineering 
data that support the structural maintenance program. Operators 
affected by the WFD rule may not fly an airplane beyond its LOV, unless 
an extended LOV is approved.
    The WFD rule does not require identifying and developing 
maintenance actions if the DAHs can show that such actions are not 
necessary to prevent WFD before the airplane reaches the LOV. Many 
LOVs, however, do depend on accomplishment of future maintenance 
actions. As stated in the WFD rule, any maintenance actions necessary 
to reach the LOV will be mandated by airworthiness directives through 
separate rulemaking actions.
    In the context of WFD, this action is necessary to enable DAHs to 
propose LOVs that allow operators the longest operational lives for 
their airplanes, and still ensure that WFD will not occur. This 
approach allows for an implementation strategy that provides 
flexibility to DAHs in determining the timing of service information 
development (with FAA approval), while providing operators with 
certainty regarding the LOV applicable to their airplanes.
    The FAA has received reports indicating fuselage skin cracking 
found between stations (STA) 767 and STA 787, just below S-14R fuselage 
skin lap splice, where a lower skin panel buckle intersected the upper 
skin of the lap splice. Fuselage skin cracking was also found between 
just below S-14R between STA 747 and STA 767. Skin buckles, wrinkles, 
or bulges may be precursors to cracks at the potential affected 
fuselage longitudinal lap splice areas on all 737NG airplanes. Fatigue 
cracks initiated at multiple locations where linear anomalies were 
found in the clad layer of the lower skin. Areas of loose paint, 
discoloration, loose fasteners, lap joint separation, or disturbed 
sealant can be indicative of areas where skin buckles, wrinkles, or 
bulges have occurred. Such areas should

[[Page 67583]]

be carefully examined for skin deformation; however, skin buckles, 
wrinkles, or bulges may also exist without other signs of skin 
distress. This condition was the result of incorrect procedures used to 
install lap splice during airplane production. This condition, if not 
addressed, could result in any small crack, any buckle, any wrinkle or 
any bulge in the fuselage skin lap splice may go undetected. Continued 
operation of the airplane with any undetected small crack, buckle, 
wrinkle or bulge in the fuselage skin lap splice could cause a large 
crack in the fuselage skin, which may result in the inability of a 
principal structural element to sustain limit load, which could result 
in reduce structural integrity of the airplane and lead to a 
decompression event.

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 Special Attention Requirements Bulletin 
737-53-1399 RB, dated May 20, 2022. This service information specifies 
procedures for a general visual inspection for any repair, any buckle, 
any wrinkle, any bulge, and any cracking at skin lap splice at 
stringers S-4 (Boeing Converted Freighter only), S-14 and S-24 (737-600 
only). This service information also describes procedures, depending on 
the configuration, for repetitive detailed inspections for buckling, 
wrinkling, bulging at unrepaired areas of affected lap splices and 
repair; repetitive detailed, high frequency eddy current (HFEC), and 
ultrasonic (UT) inspections for cracking at affected locations common 
to fuselage skin on the left and right sides and repair; and 
alternative inspections and on-condition actions.
    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 by searching for and locating 
Docket No. FAA-2022-1250.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 2,462 airplanes of U.S. registry. The FAA estimates the 
following costs to comply with this proposed AD:

                                                 Estimated Costs
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                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspections......................  Up to 34 hours x                 $0  $2,890 per           Up to $7,115,180
                                    $85 per hour = Up                    inspection cycle.    per inspection
                                    to $2,890 per                                             cycle.
                                    inspection cycle.
----------------------------------------------------------------------------------------------------------------

    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition repairs or for the alternative 
inspections and on-condition actions specified in this proposed 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

    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

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:

The Boeing Company: Docket No. FAA-2022-1250; Project Identifier AD-
2022-00763-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by December 27, 2022

(b) Affected ADs

    None.

 (c) Applicability

    This AD applies to all The Boeing Company 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.

[[Page 67584]]

(e) Unsafe Condition

    This AD was prompted by an evaluation by the design approval 
holder (DAH) indicating that the skin lap splice at stringers S-4, 
S-14, and S-24 are subject to widespread fatigue damage (WFD). The 
FAA is issuing this AD to address cracks, skin buckles, wrinkles, 
and bulges at fuselage longitudinal lap splice areas at S-4, S-14 
and S-24. This condition, if not addressed, could result in a large 
crack in the fuselage skin, which may result in the inability of a 
principal structural element to sustain limit load, which could 
result in reduced structural integrity of the airplane and lead to a 
decompression event.

(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 
Special Attention Requirements Bulletin 737-53-1399 RB, dated May 
20, 2022, do all applicable actions identified in, and in accordance 
with, the Accomplishment Instructions of Boeing Special Attention 
Requirements Bulletin 737-53-1399 RB, dated May 20, 2022.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Special Attention Service 
Bulletin 737-53-1399 RB, dated May 20, 2022, which is referred to in 
Boeing Special Attention Requirements Bulletin 737-53-1399 RB, dated 
May 20, 2022.

(h) Exceptions to Service Information Specifications

    (1) Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Special Attention Requirements 
Bulletin 737-53-1399 RB, dated May 20, 2022, use the phrase ``the 
original issue date of Boeing Special Attention Requirements 
Bulletin 737-53-1399 RB,'' this AD requires using ``the effective 
date of this AD.''
    (2) Where Boeing Special Attention Requirements Bulletin 737-53-
1399 RB, dated May 20, 2022, specifies contacting Boeing for repair 
instructions or for alternative inspections: This AD requires doing 
the repair and 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)(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, 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

    (1) For more information about this AD, contact Willard 
Ashforth, Senior Aerospace Engineer, Airframe Section, FAA, Seattle 
ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3520; email: [email protected].
    (2) 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. You may 
view this referenced 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.

    Issued on September 29, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.

[FR Doc. 2022-24244 Filed 11-8-22; 8:45 am]
BILLING CODE 4910-13-P


