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[Federal Register Volume 89, Number 231 (Monday, December 2, 2024)]
[Rules and Regulations]
[Pages 95092-95095]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-28120]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0463; Project Identifier AD-2023-00792-T; 
Amendment 39-22890; AD 2024-23-11]
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 737-8, 737-9, and 737-8200 (737 MAX) 
airplanes. This AD was prompted by a report of a non-conforming 
installation of spoiler wire bundles that led to unintended spoiler 
motion, including one instance of a flight spoiler hardover. Further 
investigation identified the potential for a hardover of more than one 
flight spoiler on the same wing, which can exceed full lateral control 
capability leading to loss of control of the airplane. This AD requires 
a one-time inspection of the clearance between the spoiler control wire 
bundles and the adjacent structure, and applicable on-condition 
actions. The FAA is issuing this AD to address the unsafe condition on 
these products.

DATES: This AD is effective January 6, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of January 6, 
2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-0463; 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 Boeing material 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.
     You may view this material at the FAA, Airworthiness 
Products Section,

[[Page 95093]]

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-
2024-0463.

FOR FURTHER INFORMATION CONTACT: Michael Closson, Aviation Safety 
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3973; 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 737-8, 737-9, and 737-8200 airplanes. The NPRM published 
in the Federal Register on March 11, 2024 (89 FR 17346). The NPRM was 
prompted by a report of a non-conforming installation of flight spoiler 
control wire bundles that led to unintended spoiler motion, including 
one instance of flight spoiler hardover. Further investigation 
identified the potential for simultaneous time-limited hardovers of 
more than one flight spoiler on the same wing, which can exceed full 
lateral control capability leading to loss of control of the airplane. 
In the NPRM, the FAA proposed to require a one-time inspection of the 
clearance between the spoiler control wire bundles and the adjacent 
structure, and applicable on-condition actions. The FAA is issuing this 
AD to address the potential for improper clearance between the spoiler 
control wire bundles and the adjacent structure. Improper clearance can 
lead to damage to the wire bundle, causing unintentional spoiler motion 
and consequent loss of control of the airplane. A hardover of more than 
one flight spoiler on the same wing can exceed full lateral control 
capability leading to loss of control of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from seven commenters: The Boeing 
Company, United Airlines, Air Line Pilots Association, International, 
and four individuals, who supported the NPRM without change.
    The FAA received additional comments from three commenters: 
SunExpress Airlines, The Foundation for Aviation Safety, and an 
individual. The following summarizes the comments received on the NPRM 
and provides the FAA's responses.

Request for Immediately Adopted Rule (IAR)

    The Foundation for Aviation Safety (the Foundation) requested \1\ 
that the FAA issue the AD as an immediately adopted rule (IAR) \2\ with 
a compliance time of 30 days instead of the proposed 36-month 
compliance time. The Foundation's rationale referenced the service 
history of this model, the FAA's use of what the Foundation described 
as an unvalidated assumption about wear rates, the presence of a 
potentially catastrophic single failure condition, and the required 
inspection is estimated to take nine hours \3\ per airplane.
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    \1\ The Foundation's comment on this AD was submitted directly 
to the FAA Administrator, but has been placed into the rulemaking 
docket.
    \2\ An ``Immediately Adopted Rule'' or ``IAR'' is an FAA term 
for a rule that is issued without first obtaining public comment, 
a.k.a a ``Final Rule with request for Comments,'' based upon good 
cause.
    \3\ Although the work-hours listed in the NPRM for the one-time 
inspection and on-condition actions amount to nine hours of work per 
airplane, no airplane would require all of the on-condition actions. 
Therefore, the actions required by this AD would take less than nine 
hours of work per airplane.
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    In addition, an individual requested the FAA require ``immediate 
repair of the defects on the identified aircraft'' due to recent Boeing 
failures.
    The FAA does not agree with the request to issue the AD as an IAR, 
or to shorten the compliance time. After conducting a risk analysis, 
the FAA did not find it necessary to issue an IAR with a shorter 
compliance time, but determined that an NPRM, which allowed the 
opportunity for public comment, was appropriate.
    As part of their argument for an IAR and shortened compliance time, 
the Foundation stated that the potential failure condition is the 
result of a single point of failure (the chafed wire to a spoiler 
actuator), which is incorrect. The NPRM was issued to address the 
potential catastrophic event of simultaneous time-limited \4\ hardovers 
of more than one flight spoiler on the same wing, which would require 
two separate specific wires to short to ground almost simultaneously.
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    \4\ This type of flight spoiler failure will be detected within 
a short time window by a software monitor, which will then fully 
retract spoiler eliminating the hardover condition, thereby limiting 
the exposure window for concurrent failures.
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    To support their argument for the IAR, the Foundation also 
questioned the FAA's assumptions regarding the use of unvalidated wire 
``wear rates'' to support the compliance times in the NPRM. The FAA 
concurs that ``wear rate'' is highly dependent upon the specific 
installation and operational environment of the wire bundle in 
question. However, the FAA did not use Boeing's ``wear rate'' in 
developing the risk analysis as suggested by the commenter. Instead, 
the FAA's analysis incorporated feedback from 737 MAX operators that 
had performed the inspections called out in Boeing Service Letter 737-
SL-293-A, dated May 17, 2022, which indicated no findings of wire 
chafing in over 650 Model 737 MAX airplanes. This, combined with the 
FAA risk analysis, showed that an NPRM was appropriate.

Request for Credit for Prior Inspections

    SunExpress Airlines requested that Boeing Service Letter 737-SL-27-
293-B, dated May 23, 2022, serve as alternative method of compliance to 
paragraphs (g) and (h) of the proposed AD. The commenter asserted that 
the Work Instructions of Boeing Service Letter 737-SL-27-293-B fulfills 
the requirements stated in Boeing Alert Requirements Bulletin 737-
27A1325 RB, dated July 14, 2023 (Alert RB 737-27A1325 RB).
    The FAA agrees that accomplishing Boeing Service Letter 737-SL-27-
293-B, dated May 23, 2022, provides some of the inspection and 
corrective action instructions called out in Alert RB 737-27A1325 RB. 
However, the FAA disagrees with giving credit for paragraphs (g) and 
(h) of this AD because the scope of the inspections in Boeing Service 
Letter 737-SL-27-293-B, dated May 23, 2022, does not include 
inspections for the outboard clamp locations and does not have certain 
of the defined clearance requirements of the Requirements Bulletin. 
Paragraph (i) of this AD allows the commenter to request an alternative 
method of compliance (AMOC) for the actions in the Service Letter that 
are duplicated in the Requirements Bulletin.

Request for Additional Guidance To Identify Affected Airplanes

    An individual requested that the FAA issue additional guidance to 
assist in identifying other airplane models that may be subject to the 
same unsafe condition.
    Such additional guidance is unnecessary. The FAA has worked with 
Boeing to identify the affected airplanes and those airplanes have been 
listed in Alert RB 737-27A1325 RB. The agency has also verified with 
Boeing that the actions and practices identified in Alert RB 737-
27A1325 RB have been incorporated in Boeing's production processes at a 
specific airplane line number, ensuring this unsafe condition does not 
exist on airplanes delivered from that line number forward.

[[Page 95094]]

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, this 
AD is adopted as proposed in the NPRM. None of the changes will 
increase the economic burden on any operator.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 737-27A1325 RB, 
dated July 14, 2023. This material specifies procedures for spoiler 
control wire bundles clearance measurement and applicable on-condition 
actions. On-condition actions include a detailed inspection of the 
spoiler control wire bundles and adjacent structure for chafing damage, 
repair of any spoiler control wire bundles and any structural damage, 
and adjustment of the spoiler control wire bundles to ensure clearance 
requirements are met.
    This material is reasonably available because the interested 
parties have access to it through their normal course of business or by 
the means identified in the ADDRESSES section.

Costs of Compliance

    The FAA estimates that this AD affects 207 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
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                                                                                    Cost per       Cost on U.S.
               Action                        Labor cost           Parts cost        product         operators
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Measurement of wire bundle clearance  1 work-hour x $85 per                $0              $85          $17,595
                                       hour = $85.
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    The FAA estimates the following costs to do any necessary repairs 
that would be required based on the results of the inspection. The 
agency has no way of determining the number of aircraft that might need 
these repairs:

                                               On-Condition Costs
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                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
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Inspection....................................  1 work-hour x $85...............              $0             $85
Rework cable bundles without chafing damage to  2 work-hours x $85 per hour =                  0             170
 wires or airplane structure.                    $170.
Rework cable bundles with chafing damage to     5 work-hours x $85 per hour =                  0             425
 wires or airplane structure.                    $425.
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    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all of the costs of 
this AD may be covered under warranty, thereby reducing the cost impact 
on affected operators.

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:

2024-23-11 The Boeing Company: Amendment 39-22890; Docket No. FAA-
2024-0463; Project Identifier AD-2023-00792-T.

(a) Effective Date

    This airworthiness directive (AD) is effective January 6, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-8, 737-9, and 
737-8200 airplanes, certificated in any category, as identified in 
Boeing Alert Requirements Bulletin 737-27A1325 RB, dated July 14, 
2023.

(d) Subject

    Air Transport Association (ATA) of America Code 27, Flight 
controls.

[[Page 95095]]

(e) Unsafe Condition

    This AD was prompted by a report of a non-conforming 
installation of spoiler wire bundles that led to unintended spoiler 
motion, including one instance of a flight spoiler hardover. Further 
investigation identified the potential for a time-limited hardover 
of more than one flight spoiler on the same wing, which can exceed 
full lateral control capability leading to loss of control of the 
airplane. The FAA is issuing this AD to address improper clearance 
between the spoiler control wire bundles and the adjacent structure, 
which can lead to damage to the wire bundle, causing unintentional 
spoiler motion. The unsafe condition, if not addressed, could result 
in loss of control 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 737-27A1325 RB, dated July 14, 2023, do 
all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-27A1325 RB, dated July 14, 2023.

    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-27A1325, dated July 14, 2023, which is referred to in Boeing 
Alert Requirements Bulletin 737-27A1325 RB, dated July 14, 2023.

(h) Exception to Service Information Specifications

    Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
27A1325 RB, dated July 14, 2023, use the phrase ``the original issue 
date of Requirements Bulletin 737-27A1325 RB,'' this AD requires 
using the effective date 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 
(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 Michael Closson, 
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 
98198; phone: 206-231-3973; email: [email protected].
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the address 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 material listed in this 
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this material as applicable to do the actions 
required by this AD, unless the AD specifies otherwise.
    (i) Boeing Alert Requirements Bulletin 737-27A1325 RB, dated 
July 14, 2023.
    (ii) [Reserved]
    (3) For Boeing material 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 material 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 November 14, 2024.
John P. Piccola, Jr.,
Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2024-28120 Filed 11-29-24; 8:45 am]
BILLING CODE 4910-13-P
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