[Federal Register Volume 88, Number 101 (Thursday, May 25, 2023)]
[Proposed Rules]
[Pages 33849-33851]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-11199]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1041; Project Identifier AD-2022-01223-T]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company 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 certain The Boeing Company Model 737-600, 737-700, and 737-800 
series airplanes. This proposed AD was prompted by an evaluation by the 
design approval holder (DAH) indicating the fuselage skin at the double 
row of fasteners centered on certain stringers is subject to skin 
cracking. This proposed AD is intended to complete certain programs to 
support the airplane reaching its limit of validity (LOV). This 
proposed AD would require repetitive inspections for cracks of skin 
repairs at Stringer S-17, and corrective actions if necessary. 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 July 10, 
2023.

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. FAA-2023-1041; 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 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; 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 by searching for and locating Docket No. FAA-2023-1041.

FOR FURTHER INFORMATION CONTACT: Bill 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-2023-1041; Project Identifier 
AD-2022-01223-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, Senior Aerospace Engineer, Airframe Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-
3520; email: [email protected]. Any commentary that the FAA 
receives that is not specifically designated as CBI will be placed in 
the public docket for this rulemaking.

Background

    As described in FAA Advisory Circular 120-104 (http://www.faa.gov/documentLibrary/media/Advisory_Circular/120-104.pdf), several programs 
have been developed to support initiatives that will ensure the 
continued airworthiness of aging airplane structure. The last element 
of those initiatives is the requirement to establish an LOV of the 
engineering data that support the structural maintenance program under 
14 CFR 26.21. This proposed AD is the result of an assessment of the 
previously established programs by the DAH during the process of 
establishing the LOV for the affected airplanes. The actions specified 
in this proposed AD are necessary to complete certain programs to 
ensure the continued airworthiness of aging airplane structure and to 
support an airplane reaching its LOV.
    The FAA has received a report indicating the fuselage skin at the 
double row of fasteners centered on stringers S-17L and S-17R, at 
station (STA) 360 to STA 380 and at STA 888 to STA 907 is subject to 
skin cracking. During airplane production, a structural preload was 
created in the body skin during installation of S-17 stringers. 
Analysis by Boeing shows that this preload, combined with pressure 
cycles, can cause cracks in the skin prior to reaching the design 
service objective (DSO). For Model 737-600, 737-700, and 737-800 series 
airplanes after Line Number 269, the sequence of assembly was changed 
to eliminate the preload.

[[Page 33850]]

    Boeing issued Service Bulletin 737-53A1217, dated August 9, 2001, 
to specify repetitive inspections of the skin for cracking; however, 
that service information was not required by an AD because existing 
maintenance planning document (MPD) inspections were determined to be 
adequate to address skin cracking. Several airplanes have had 
inspections and/or repairs accomplished at STA 360 to STA 380. The FAA 
and Boeing have since determined that certain existing post-repair 
inspections are inadequate to address the unsafe condition. The actions 
in paragraph (g) of this proposed AD would therefore apply only to 
airplanes on which a repair has been done as specified in Boeing Alert 
Service Bulletin 737-53A1217 (identified as Group 1 through 3, 
Configuration 3 in Boeing Alert Service Bulletin 737-53A1217). Once a 
certain repair is accomplished on an airplane, post-repair inspections 
must be accomplished on that airplane, as specified in this proposed 
AD. This proposed AD would require only the post-repair inspections and 
corrective actions specified in Tables 3 through 6 of Boeing Alert 
Service Bulletin 737-53A1217. Airplanes identified as Group 1 through 
3, Configurations 1 and 2 in Boeing Alert Service Bulletin 737-53A1217 
become Configuration 3 airplanes after accomplishing a repair specified 
in Boeing Alert Service Bulletin 737-53A1217. This unsafe condition, if 
not addressed, could result in an undetected crack that could grow to 
critical length, and result in possible rapid decompression and 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 Service Bulletin 737-53A1217, 
Revision 1, dated September 8, 2022. This service information specifies 
procedures for, among other actions, repetitive internal and external 
detailed inspections, low frequency eddy current (LFEC), and medium 
frequency eddy current (MFEC) inspections for cracks of the skin repair 
of S-17, STA 360 to STA 380 and STA 888 to STA 907, left and right 
sides of the airplane. Corrective actions include 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.

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions identified 
as ``RC'' (required for compliance) in the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-53A1217, Revision 1, dated 
September 8, 2022, 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. FAA-2023-1041.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 106 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
----------------------------------------------------------------------------------------------------------------
External Post Repair Inspection..  56 work-hours x $85               0  $4,760 per           $504,560 per
                                    per hour = $4,760                    inspection cycle.    inspection cycle.
                                    per inspection
                                    cycle.
Internal Post Repair Inspections.  52 work-hours x $85               0  $4,420 per           $468,520 per
                                    per hour = $4,420                    inspection cycle.    inspection cycle.
                                    per inspection
                                    cycle.
----------------------------------------------------------------------------------------------------------------

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

[[Page 33851]]

The Boeing Company: Docket No. FAA-2023-1041; Project Identifier AD-
2022-01223-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by July 10, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-600, 737-700, 
and 737-800 series airplanes, certificated in any category, as 
identified in Boeing Alert Service Bulletin 737-53A1217, Revision 1, 
dated September 8, 2022.

(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 the fuselage skin at the double row of 
fasteners centered on certain stringers is subject to skin cracking. 
The FAA is issuing this AD to address fatigue cracks at certain 
fasteners centered on Stringers S-17L and S-17R, at station (STA) 
360 to STA 380 and at STA 888 to STA 907. Such undetected fatigue 
cracks, if not addressed, could grow to a critical length, which 
could result in rapid decompression and loss of 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 through 3, Configuration 3 airplanes as identified 
in Boeing Alert Service Bulletin 737-53A1217, Revision 1, dated 
September 8, 2022: Except as specified in paragraph (h) of this AD, 
at the applicable times specified in Tables 3 through 6 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1217, 
Revision 1, dated September 8, 2022, do all applicable actions 
identified as ``RC'' (required for compliance) in, and in accordance 
with, the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1217, Revision 1, dated September 8, 2022.

(h) Exceptions to Service Information Specifications

    Where Boeing Alert Service Bulletin 737-53A1217, Revision 1, 
dated September 8, 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.

(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 (k) 
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.
    (4) Except as specified by paragraph (h) of this AD: For service 
information that contains steps that are labeled as Required for 
Compliance (RC), the provisions of paragraphs (i)(4)(i) and (ii) of 
this AD apply.
    (i) The steps labeled as RC, including substeps under an RC step 
and any figures identified in an RC step, must be done to comply 
with the AD. If a step or substep is labeled ``RC Exempt,'' then the 
RC requirement is removed from that step or substep. An AMOC is 
required for any deviations to RC steps, including substeps and 
identified figures.
    (ii) Steps not labeled as RC may be deviated from using accepted 
methods in accordance with the operator's maintenance or inspection 
program without obtaining approval of an AMOC, provided the RC 
steps, including substeps and identified figures, can still be done 
as specified, and the airplane can be put back in an airworthy 
condition.

(j) Related Information

    For more information about this AD, contact Bill 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].

(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 Service Bulletin 737-53A1217, Revision 1, dated 
September 8, 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 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: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on May 9, 2023.
Michael Linegang,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-11199 Filed 5-24-23; 8:45 am]
BILLING CODE 4910-13-P