[Federal Register Volume 88, Number 24 (Monday, February 6, 2023)]
[Rules and Regulations]
[Pages 7575-7578]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-02371]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0874; Project Identifier AD-2022-00337-T; 
Amendment 39-22307; AD 2023-01-13]
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 DC-9-81 (MD-81), DC-9-82 (MD-82), DC-
9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes. 
This AD was prompted by an evaluation by the design approval holder 
(DAH) indicating that certain center wing lower stringers are subject 
to widespread fatigue damage (WFD). WFD analysis found that fatigue 
cracks could grow to a critical length after the structural 
modification point (SMP) for these center wing lower stringers. This AD 
requires replacing certain left and right side center wing lower 
stringers. The FAA is issuing this AD to address the unsafe condition 
on these products.

DATES: This AD is effective March 13, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of March 13, 
2023.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2022-0874; 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

[[Page 7576]]

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-2022-0874.

FOR FURTHER INFORMATION CONTACT: Manuel Hernandez, Aerospace Engineer, 
Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount 
Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5256; 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 DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and 
DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes. The NPRM 
published in the Federal Register on August 31, 2022 (87 FR 53419). The 
NPRM was prompted by an evaluation by the DAH indicating that certain 
center wing lower stringers are subject to WFD. WFD analysis found that 
fatigue cracks could grow to a critical length after the SMP for these 
center wing lower stringers. In the NPRM, the FAA proposed to require 
replacing certain left and right side center wing lower stringers. The 
FAA is issuing this AD to address potential fatigue cracking of the 
right and left side center wing lower stringers S-11 through S-22 
between wing stations Xcw=13 and Xcw=15. If not addressed, undetected 
fatigue cracks could grow to a critical length after the SMP at 81,740 
total flight cycles. Any undetected cracks in three or more adjacent 
stringers in the right or left side center wing lower stringers S-11 
through S-22 may result in a principal structural element's inability 
to sustain limit load, which could adversely affect the structural 
integrity of the airplane. Performing the replacement required by this 
AD terminates the repetitive inspections required by AD 2020-10-10 
Amendment 39-19913 (85 FR 31046, May 22, 2020) (AD 2020-10-10, which 
addresses the unsafe condition until the airplane reaches the SMP).

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments on the NPRM from Boeing, and three 
individuals. The comments from one individual were outside the scope of 
this rulemaking. The following presents the comments received and the 
FAA's response to each comment.

Request To Allow Certified Non-Boeing Mechanics To Perform Replacements

    An individual requested that a certified mechanic not hired by 
Boeing be allowed to perform the replacement specified in the proposed 
AD. The commenter stated that it appears that Boeing must take care of 
the replacements, which must be paid for by the airplanes' owners, 
which could create a conflict of interest. Another commenter suggested 
that an external party should inspect the repaired airplanes to ensure 
no further issues will arise.
    The FAA agrees to clarify. Unless specified otherwise, ADs allow an 
FAA-approved licensed mechanic authorized to do maintenance to perform 
the replacement actions. Operators may therefore use a qualified 
mechanic of their choice, and do not have to use a Boeing employee for 
the replacements. The FAA has not changed this AD regarding this issue.

Request To Clarify Certain Language in the Background Section of the 
Proposed AD

    Boeing requested that certain language in the Background section of 
the proposed AD be changed for clarification. Boeing asked that a 
sentence describing AD 2020-10-10 be revised. The sentence in the NPRM 
reads: ``AD 2020-10-10 requires repetitive inspections for cracking in 
the left and right side center wing lower skin at stringers S-18 
through S-20, the fastener holes common to stringers S-11 through S-22, 
and the forward and aft skins, and repair.'' Boeing asked that the 
sentence be revised to read: ``AD 2020-10-10 requires repetitive 
inspections for cracking in the left and right side fastener holes 
common to stringers S-11 through S-22 and the forward and aft skins, 
and center wing lower skin at stringers S-18 through S-20, and 
repair.'' Boeing stated that the revised language would correctly 
identify the inspection requirements and list them in the same order as 
the description in the service information.
    The FAA agrees that the proposed wording better matches the 
description in the service information. However, that sentence is not 
carried over to this final rule. Therefore, the FAA has not changed 
this AD regarding this issue.

Request To Clarify Certain Language in Paragraph (e) of the Proposed AD

    Boeing requested that the language in paragraph (e) of the proposed 
AD be clarified to specify that this AD is being issued to address 
``potential'' fatigue cracking. Boeing stated that not all structure 
subject to replacement will have developed fatigue cracking and that 
the required action involves proactive replacement.
    The FAA agrees with the request to change the language. The phrase 
``address fatigue cracking'' in paragraph (e) of this AD has been 
changed to read ``address potential fatigue cracking.''

Request To Clarify Certain Language in the Explanation of Compliance 
Time Paragraph of the Proposed AD

    Boeing requested that the language in the Explanation of Compliance 
Time paragraph of the proposed AD be changed for clarification. Boeing 
stated that all structure subject to replacement is certified type 
design and not all will have developed fatigue cracking, therefore 
replacing the term ``discrepant structure'' with the term ``certain 
structure'' would be more consistent with the language of the SUMMARY 
section.
    The FAA agrees that not all structure subject to replacement will 
have developed fatigue cracks at SMP. However, that sentence is not 
carried over to this final rule. Therefore, the FAA has not changed 
this AD regarding this issue.

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 MD80-57A246 RB, 
dated December 17, 2021. This service information specifies procedures 
for replacement of the center wing lower stringers S-11 through S-22 
between Xcw=0 and Xcw=121.688, left and right sides.

[[Page 7577]]

    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 22 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Replacement...........................  1,572 work-hours x $85          $216,000        $349,620      $7,691,640
                                         per hour = $133,620.
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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:

2023-01-13 The Boeing Company: Amendment 39-22307; Docket No. FAA-
2022-0874; Project Identifier AD-2022-00337-T.

(a) Effective Date

    This airworthiness directive (AD) is effective March 13, 2023.

(b) Affected ADs

    This AD affects AD 2020-10-10, Amendment 39-19913 (85 FR 31046, 
May 22, 2020) (AD 2020-10-10).

(c) Applicability

    This AD applies to The Boeing Company Model DC-9-81 (MD-81), DC-
9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and 
Model MD-88 airplanes, certificated in any category, as identified 
in Boeing Alert Requirements Bulletin MD80-57A246 RB, dated December 
17, 2021.

(d) Subject

    Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by an evaluation by the design approval 
holder (DAH) indicating that the center wing lower stringers S-11 
through S-22 are subject to widespread fatigue damage (WFD). The FAA 
is issuing this AD to address potential fatigue cracking of the 
right and left side center wing lower stringers S-11 through S-22 
between wing stations Xcw=13 and Xcw=15. If not addressed, 
undetected fatigue cracks could grow to a critical length after the 
structural modification point (SMP) at 81,740 total flight cycles. 
Any undetected cracks in three or more adjacent stringers in the 
right or left side center wing lower stringers S-11 through S-22 may 
result in a principal structural element's inability to sustain 
limit load, which could adversely affect the 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 MD80-57A246 RB, dated December 17, 2021, 
do all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
MD80-57A246 RB, dated December 17, 2021.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
MD80-57A246, dated December 17, 2021, which is referred to in Boeing 
Alert Requirements Bulletin MD80-57A246 RB, dated December 17, 2021.

(h) Exceptions to Service Information Specifications

    Where Boeing Alert Requirements Bulletin MD80-57A246 RB, dated 
December 17, 2021, specifies contacting Boeing for replacement 
instructions: This AD requires doing the replacement using a method 
approved in accordance with the procedures specified in paragraph 
(j) of this AD.

(i) Terminating Action for AD 2020-10-10

    Accomplishment of the replacement specified in the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
MD80-57A246 RB, dated December 17, 2021, terminates all of the 
requirements of AD 2020-10-10.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles 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 (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.

[[Page 7578]]

    (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, Los 
Angeles 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.

(k) Related Information

    For more information about this AD, contact Manuel Hernandez, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5256; email: [email protected].

(l) 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 MD80-57A246 RB, dated 
December 17, 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; 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 January 13, 2023.
Gaetano A. Sciortino,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-02371 Filed 2-3-23; 8:45 am]
BILLING CODE 4910-13-P


