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[Federal Register Volume 89, Number 231 (Monday, December 2, 2024)]
[Rules and Regulations]
[Pages 95086-95088]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-28134]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1897; Project Identifier AD-2023-00774-T; 
Amendment 39-22882; AD 2024-23-03]
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 737-300 and -400 series airplanes. 
This AD was prompted by a report that flight control rigging tolerances 
could result in spoiler deflection not reaching the minimal level 
required to engage the cruise thrust split monitor (MONFD) used by the 
autothrottle (A/T) system. This AD requires changing certain wire 
bundles, installing a new housing assembly, removing the mechanical 
aileron force limiter (MAFL), doing an inspection or records check to 
determine if certain flight control computers (FCCs) are installed, and 
performing 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-2024-1897; 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, 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-2024-1897.

FOR FURTHER INFORMATION CONTACT: Eric Igama, Aviation Safety Engineer, 
FAA, 2200 South 216th Street, Des Moines, WA 98198; telephone 562-627-
5388; 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 737-300 and -400 series airplanes. The NPRM published in 
the Federal Register on July 29, 2024 (89 FR 60836). The NPRM was 
prompted by a report indicating that flight control rigging tolerances 
could result in spoiler deflection not reaching the minimal level 
required to engage the MONFD used by the A/T system. In the NPRM, the 
FAA proposed to require changing certain wire bundles, installing a new 
housing assembly, removing the mechanical aileron force limiter (MAFL), 
doing an inspection or records check to determine if certain flight 
control computers (FCCs) are installed, and performing applicable on-
condition actions. The FAA is issuing this AD to address failure of the 
spoiler deflection to engage the MONFD, which could lead to significant 
throttle split, leading to asymmetric thrust and the subsequent lack of 
autothrottle disengagement, uncommanded roll, and consequent loss of 
control of the airplane and reduced ability of the flightcrew to 
maintain the safe flight and landing of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received a comment from Aviation Partners Boeing. The 
following presents the comment received on the NPRM and the FAA's 
response.

Effect of Winglets on Accomplishment of the Proposed Actions

    Aviation Partners Boeing stated that the installation of winglets 
per Supplemental Type Certificate (STC) ST01219SE does not affect 
compliance with the proposed actions.
    The FAA agrees with the commenter that STC ST01219SE does not 
affect the accomplishment of the manufacturer's service instructions. 
Therefore, the installation of STC ST01219SE does not affect the 
ability to accomplish the actions required by this AD. 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. 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 737-22A1399 RB, 
dated April 13, 2023. This material specifies procedures for changing 
certain wire bundles, installing a new housing assembly, removing the 
MAFL, doing an inspection or records check to determine if certain FCCs 
are installed (FCCs that have an electronic aileron limiter (EAL) 
revision), and performing applicable on-condition actions. On-condition 
actions include installing new FCCs or re-installing kept FCCs (the 
installation includes doing specified tests and applicable corrective 
actions until the tests are passed).
    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 110 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

[[Page 95087]]

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
            Action                 Labor cost      Parts cost       Cost per product      Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
Wire bundle change, MAFL        Up to 10 work-             $0   Up to $850.............  Up to $93,500.
 removal, housing assembly       hours x $85 per
 installation, and inspection/   hour = up to
 records review.                 $850.
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    The FAA estimates the following costs to do any on-condition 
actions that would be required based on the results of the inspection/
records review. The agency has no way of determining the number of 
aircraft that might need these on-condition actions:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Installation of FCCs.........................  2 work-hours x $85 per hour =            $7,250           $7,420
                                                $170.
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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:

2024-23-03 The Boeing Company: Amendment 39-22882; Docket No. FAA-
2024-1897; Project Identifier AD-2023-00774-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 737-300 and -400 
series airplanes, certificated in any category, as identified in 
Boeing Alert Requirements Bulletin 737-22A1399 RB, dated April 13, 
2023.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a report that flight control rigging 
tolerances could result in spoiler deflection not reaching the 
minimal level required to engage the cruise thrust split monitor 
(MONFD) used by the autothrottle (A/T) system. The FAA is issuing 
this AD to address failure of the spoiler deflection to engage the 
MONFD. The unsafe condition, if not addressed, could lead to 
significant throttle split, leading to asymmetric thrust and the 
subsequent lack of autothrottle disengagement, which could result in 
an uncommanded roll and consequent loss of control of the airplane, 
and reduced ability of the flightcrew to maintain the safe flight 
and landing 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 737-22A1399 RB, dated April 13, 2023, do 
all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
737-22A1399 RB, dated April 13, 2023.

    Note 1 to paragraph (g):  Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
737-22A1399, dated April 13, 2023, which is referred to in Boeing 
Alert Requirements Bulletin 737-22A1399 RB, dated April 13, 2023.

(h) Exceptions to Requirements Bulletin Specifications

    Where the Compliance Time columns of the table in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 737-
22A1399 RB, dated April 13, 2023, use the phrase ``the original 
issue date of Requirements Bulletin 737-22A1399 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,

[[Page 95088]]

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 Eric Igama, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; phone: 562-627-5388; email: [email protected].
    (2) Material 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 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 737-22A1399 RB, dated 
April 13, 2023.
    (ii) [Reserved]
    (3) For the 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 
Street, 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 7, 2024.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2024-28134 Filed 11-29-24; 8:45 am]
BILLING CODE 4910-13-P
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