[Federal Register Volume 90, Number 219 (Monday, November 17, 2025)]
[Proposed Rules]
[Pages 51216-51218]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-20013]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-3997; Project Identifier AD-2025-01471-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 all The Boeing Company Model 777-200, -200LR, -300, -300ER, and
777F series airplanes. This proposed AD was prompted by a report of
overheated alternating current motor pumps (ACMP) that caused a fire in
the main landing gear (MLG) wheel well. This proposed AD would require
a records check or inspection for any installed ACMP with a certain
part number and applicable on-condition actions. This proposed AD would
also prohibit the installation of affected parts. 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 January 2,
2026.
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-2025-3997; 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 Boeing material identified in this proposed 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-2025-3997.
FOR FURTHER INFORMATION CONTACT: Michael Sheldon, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 651-
955-7451; 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 using a method listed
under the ADDRESSES section. Include ``Docket No. FAA-2025-3997;
Project Identifier AD-2025-01471-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
Michael Sheldon, Aviation Safety Engineer, FAA, 2200 South 216th St.,
Des Moines, WA 98198; phone: 651-955-7451; 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
The FAA has received a report from an operator of a fire in the MLG
wheel well on a Model 777 airplane. A subsequent investigation found
that the cause of the fire was an overheated ACMP. Further
investigation found that a lock washer and nut was missing from a
moving contact in the related electrical load control unit (ELCU). The
missing lock washer and nut left the main contact operator bar
unrestrained and in a position which let two-phase power go to the ACMP
which caused the ACMP to overheat, leak hydraulic fluid and
subsequently start a fire in the MLG wheel well. As a result, the
design of the ACMP has been modified to include fusible links as a new
feature to prevent the ACMP overheat if one of the electrical phases
fails. Additionally, the manufacturer has determined that part number
731966 on continuous two-phase power application may cause the pump to
overheat and ignite a fire in the wheel well. Part number 731966 can be
subjected to a single failure of the ELCU that results in continuous
two-phase power application with no ability to remove power. This
condition, if not addressed, could result in the ACMP overheating and
igniting a fire in the wheel well and consequent damage to the
airplane, loss of continued safe flight and landing and/or personnel
injury.
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.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Boeing Alert Requirements Bulletin 777-29A0047 RB,
dated September 11, 2025. This
[[Page 51217]]
material specifies procedures for a records check or inspection for any
installed ACMP with part number 731966, and applicable on-condition
actions. On-condition actions include replacing any ACMP part number
731966 with ACMP part number 3033115-100 or later approved ACMP part
number at affected locations. 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.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified
in the material already described, except for any differences
identified as exceptions in the regulatory text of this proposed AD.
This proposed AD would also prohibit the installation of affected
parts. For information on the procedures and compliance times, see this
material at regulations.gov under Docket No. FAA-2025-3997.
Differences Between This Proposed AD and the Referenced Material
The effectivity of Boeing Alert Requirements Bulletin 777-29A0047
RB, dated September 11, 2025, is limited to The Boeing Company Model
777-200, -200LR,-300, -300ER, and 777F series airplanes having line
numbers 1 through 1566 inclusive, and 1568 through 1571 inclusive.
However, the applicability of this proposed AD includes all Model 777-
200, -200LR, -300, -300ER, and 777F series airplanes. Because the
affected ACMP are rotable parts, the FAA has determined that these
parts could later be installed on airplanes that were initially
delivered with acceptable ACMPs, thereby subjecting those airplanes to
the unsafe condition. The FAA has confirmed that the Accomplishment
Instructions in Boeing Alert Requirements Bulletin 777-29A0047 RB,
dated September 11, 2025, are applicable to the expanded group of
airplanes.
Boeing Alert Requirements Bulletin 777-29A0047 RB, dated September
11, 2025, refers to ACMP part number 3033115-100 as an acceptable part.
However, the Boeing aircraft maintenance manual (AMM) identifies part
numbers 66133-06 or 66068-08 as additional acceptable parts.
Accordingly, the FAA has added paragraph (h)(2) to this proposed AD to
allow those parts as alternative replacement parts.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 340 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Inspection/Records review............. 2 work-hours x $85 per $0 $170 $57,800
hour = $170.
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The FAA estimates the following costs to do any necessary
replacements that would be required based on the results of the
proposed inspection. The agency has no way of determining the number of
aircraft that might need this replacement:
On-Condition Costs
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Action Labor cost Parts cost Cost per product
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Replacement........................ 5 work-hours x $85 per hour Up to $76,674......... Up to $77,099.
= $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 proposed 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
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.
[[Page 51218]]
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-2025-3997; Project Identifier AD-
2025-01471-T.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by January 2, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to all The Boeing Company Model 777-200, -200LR,
-300, -300ER, and 777F series airplanes, certificated in any
category.
(d) Subject
Air Transport Association (ATA) of America Code 29, Hydraulic
Power.
(e) Unsafe Condition
This AD was prompted by a report of an overheated alternating
current motor pump (ACMP) that caused a fire in the main landing
gear (MLG) wheel well. A subsequent investigation found that the
cause of the fire was an overheated ACMP. Further investigation
found that a lock washer and nut was missing from a moving contact
in the related electrical load control unit (ELCU). The FAA is
issuing this AD to address a single failure of the ELCU in the ACMP.
The unsafe condition, if not addressed, could result in the ACMP
overheating and igniting a fire in the wheel well and consequent
damage to the airplane, loss of continued safe flight and landing
and/or personnel injury.
(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 777-29A0047 RB, dated September 11,
2025, do all applicable actions identified in, and in accordance
with, the Accomplishment Instructions of Boeing Alert Requirements
Bulletin 777-29A0047 RB, dated September 11, 2025.
Note 1 to paragraph (g): Guidance for accomplishing the actions
required by this AD can be found in Boeing Alert Service Bulletin
777-29A0047, dated September 11, 2025, which is referred to in
Boeing Alert Requirements Bulletin 777-29A0047 RB, dated September
11, 2025.
(h) Exceptions to Requirements Bulletin Specifications
(1) Where the Compliance Time column of the table in the
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 777-
29A0047 RB, dated September 11, 2025, refers to the original issue
date of Requirements Bulletin 777-29A0047 RB, this AD requires using
the effective date of this AD.
(2) Where Boeing Alert Requirements Bulletin 777-29A0047 RB,
dated September 11, 2025, refers to part number 3033115-100 as a
replacement part, for this AD, part numbers 66133-06 or 66068-08 are
also acceptable replacement parts.
(i) Parts Installation Prohibition
As of the effective date of this AD, no person may install any
ACMP, having part number 731966, on any airplane.
(j) 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 Continued Operational
Safety Branch, send it to the attention of the person identified in
paragraph (k)(1) of this AD. Information may be emailed to:
[email protected]. Before using any approved AMOC, notify your
appropriate principal inspector, or lacking a principal inspector,
the manager of the responsible Flight Standards Office.
(2) 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.
(k) Additional Information
(1) For more information about this AD, contact Michael Sheldon,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 651-955-7451; email: [email protected].
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (l)(3)
this AD.
(l) 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 777-29A0047 RB, dated
September 11, 2025.
(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 5, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft
Certification Service.
[FR Doc. 2025-20013 Filed 11-14-25; 8:45 am]
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