Proposed Rule2025-23100
Airworthiness Directives; Airbus Helicopters
Primary source
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Published
December 17, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to supersede Airworthiness Directive (AD) 2023-01-04, which applies to all Airbus Helicopters Model AS350B, AS350BA, AS350B1, AS350B2, AS350B3, AS350D, AS355E, AS355F, AS355F1, AS355F2, AS355N, and AS355NP helicopters. AD 2023-01-04 requires, for helicopters with certain part-numbered tail rotor head (TRH) spider pitch change units installed, inspecting the spider pitch change nut (nut) for correct installation; marking a 2 to 5 mm wide black paint index mark and repetitively inspecting the alignment of the marking; and performing additional inspections and corrective actions if necessary. Since the FAA issued AD 2023-01-04, new or more restrictive airworthiness limitations were issued, which terminated the requirement for the repetitive inspections of the black paint index marking. This proposed AD would require the same actions of AD 2023-01-04, except for the repetitive black paint index marking inspection and would prohibit installing certain parts unless certain requirements are met. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 90 Issue 240 (Wednesday, December 17, 2025)</title>
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[Federal Register Volume 90, Number 240 (Wednesday, December 17, 2025)]
[Proposed Rules]
[Pages 58512-58515]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-23100]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
========================================================================
Federal Register / Vol. 90, No. 240 / Wednesday, December 17, 2025 /
Proposed Rules
[[Page 58512]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-5387; Project Identifier MCAI-2024-00399-R]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2023-01-04, which applies to all Airbus Helicopters Model AS350B,
AS350BA, AS350B1, AS350B2, AS350B3, AS350D, AS355E, AS355F, AS355F1,
AS355F2, AS355N, and AS355NP helicopters. AD 2023-01-04 requires, for
helicopters with certain part-numbered tail rotor head (TRH) spider
pitch change units installed, inspecting the spider pitch change nut
(nut) for correct installation; marking a 2 to 5 mm wide black paint
index mark and repetitively inspecting the alignment of the marking;
and performing additional inspections and corrective actions if
necessary. Since the FAA issued AD 2023-01-04, new or more restrictive
airworthiness limitations were issued, which terminated the requirement
for the repetitive inspections of the black paint index marking. This
proposed AD would require the same actions of AD 2023-01-04, except for
the repetitive black paint index marking inspection and would prohibit
installing certain parts unless certain requirements are met. The FAA
is proposing this AD to address the unsafe condition on these products.
DATES: The FAA must receive comments on this NPRM by February 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:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-5387; 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, the mandatory continuing airworthiness
information (MCAI) any comments received, and other information. The
street address for Docket Operations is listed above.
Material Incorporated by Reference:
<bullet> For Airbus Helicopters material identified in this
proposed AD, contact Airbus Helicopters, 2701 North Forum Drive, Grand
Prairie, TX 75052; phone: (972) 641-0000 or (800) 232-0323; fax: (972)
641-3775; website: <a href="http://airbus.com/en/products-services/helicopters/hcare-services/airbusworld">airbus.com/en/products-services/helicopters/hcare-services/airbusworld</a>. It is also available at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-5387.
<bullet> You may view this material at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room 6N
321, Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110.
FOR FURTHER INFORMATION CONTACT: Matthew Williams, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (316) 946-4134; email: <a href="/cdn-cgi/l/email-protection#64090510100c01134a104a130d08080d050917240205054a030b12"><span class="__cf_email__" data-cfemail="ec818d989884899bc298c29b858080858d819fac8a8d8dc28b839a">[email protected]</span></a>.
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-2025-5387; Project Identifier
MCAI-2024-00399-R'' 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
the 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
<a href="http://regulations.gov">regulations.gov</a>, 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
Matthew Williams, Aviation Safety Engineer, FAA, 1600 Stewart Avenue,
Suite 410, Westbury, NY 11590. Any commentary that the FAA receives
which is not specifically designated as CBI will be placed in the
public docket for this rulemaking.
Background
The FAA issued AD 2023-01-04, Amendment 39-22298 (88 FR 6618,
February 1, 2023) (AD 2023-01-04), for Airbus Helicopters Model AS350B,
AS350BA, AS350B1, AS350B2, AS350B3, AS350D, AS355E, AS355F, AS355F1,
AS355F2, AS355N, and AS355NP helicopters. AD 2023-01-04 was prompted by
an MCAI originated by the European Union Aviation Safety Agency (EASA),
which is the Technical Agent for the Member States of the European
Union. EASA issued AD 2021-0282, dated December 17, 2021 (EASA AD 2021-
0282), to address loss of the TRH pitch change control.
[[Page 58513]]
AD 2023-01-04 requires, for helicopters with certain part-numbered
TRH pitch change units installed, inspecting for correct installation
of the nut; marking a 2 to 5 mm wide black paint index mark to identify
the position of certain parts; and after the initial marking,
repetitively inspecting the alignment of the marking; and additional
inspections and corrective actions if necessary. Additionally, AD 2023-
01-04 prohibits installing an affected part on a helicopter unless
certain requirements are met. The FAA issued AD 2023-01-04 to detect
improper installation of the nut and improper alignment of a black
index marking.
Actions Since AD 2023-01-04 Was Issued
Since the FAA issued AD 2023-01-04, EASA superseded AD 2021-0282
and issued EASA AD 2021-0282R1, Revision 1, dated July 10, 2024 (EASA
AD 2021-0282R1) (also referred to as the MCAI), to address an unsafe
condition on all Airbus Helicopters Model AS 350 B, AS 350 BA, AS 350
BB, AS 350 B1, AS 350 B2, AS 350 B3, AS 350 D, AS 355 E, AS 355 F, AS
355 F1, AS 355 F2, AS 355 N, and AS 355 NP helicopters. The MCAI states
the manufacturer revised the Airworthiness Limitations Section (ALS),
as applicable, which now includes the repetitive black index marking
checks (inspections).
Additionally, for this NPRM, the FAA is updating the name of the
TRH spider pitch change unit to TRH pitch change unit as defined in the
required material. The FAA is issuing this proposed AD to detect
improper installation of the nut and improper alignment of a black
index marking. The unsafe condition, if not addressed, could result in
loss of the TRH pitch change control and consequent loss of control of
the helicopter.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-5387.
Relationship Between This Proposed AD and Other Relevant Rulemaking
EASA AD 2021-0282R1 specifies that the manufacturer revised the
ALS, for Airbus Helicopters Model AS350 and AS355 helicopters as
applicable. The revised ALS for each model now incorporates the
periodic black index marking inspections. The FAA is evaluating this
issue and may take further rulemaking action to accommodate these ALS
amendments.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Airbus Helicopters Alert Service Bulletin (ASB)
No. AS350-05.01.03, and Airbus Helicopters ASB No. AS355-05.00.86, both
Revision 0 and dated July 8, 2024, which include Figure 1 that
identifies the position of the TRH pitch change unit and of the bearing
spacer to be marked with a 2 to 5 mm wide black paint index mark. This
material also specifies procedures for inspecting the condition and
installation of the nut; and inspecting the application and alignment
of the black index mark on the TRH pitch change unit and the bearing
spacer.
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.
FAA's Determination
These products have been approved by the civil aviation authority
of another country and are approved for operation in the United States.
Pursuant to the FAA's bilateral agreement with this State of Design
Authority, it has notified the FAA of the unsafe condition described in
the MCAI and material referenced above. 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.
Proposed AD Requirements in This NPRM
This proposed AD would require the same actions as AD 2023-01-04
except it would only require the initial black paint index marking
inspection, not the repetitive inspections. Additionally, this proposed
AD would prohibit installing an affected part on a helicopter unless
certain requirements are met.
Differences Between This Proposed AD and the MCAI
The MCAI applies to Airbus Helicopters Model AS350BB, whereas this
proposed AD does not because that model does not have an FAA type
certificate.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 972 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD.
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
Inspect the nut.......................... 1 work-hour x $85 per hour $0 $85 $82,620
= $85.
Inspect alignment of marking............. 1 work-hour x $85 per hour 0 85 82,620
= $85.
Place black paint marking................ 1 work-hour x $85 per hour 0 85 82,620
= $85.
----------------------------------------------------------------------------------------------------------------
The FAA estimates the following costs to do any repairs/
replacements that would be required based on the results of the
inspection. The agency has no way of determining the number of
helicopters that might need these repairs or replacements.
On-Condition Costs
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Inspect the TRH pitch change unit.. 13 work-hours x $85 $0 $1,105.
per hour = $1,105.
Replace bushes..................... 1 work-hours x $85 5,918 $6,003 per helicopter.
per hour = $85.
Replace a rotating plate........... 1 work-hours x $85 27,375 $27,460 per helicopter.
per hour = $85.
----------------------------------------------------------------------------------------------------------------
[[Page 58514]]
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 that the 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:
0
a. Removing Airworthiness Directive 2023-01-04, Amendment 39-22298 (88
FR 6618, February 1, 2023); and
0
b. Adding the following new airworthiness directive:
Airbus Helicopters: Docket No. FAA-2025-5387; Project Identifier
MCAI-2024-00399-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by February 2, 2026.
(b) Affected ADs
This AD replaces AD 2023-01-04, Amendment 39-22298 (88 FR 6618,
February 1, 2023).
(c) Applicability
This AD applies to Airbus Helicopters Model AS350B, AS350BA,
AS350B1, AS350B2, AS350B3, AS350D, AS355E, AS355F, AS355F1, AS355F2,
AS355N, and AS355NP helicopters, certificated in any category.
Note 1 to paragraph (c): Helicopters with AS350B3e designation
are Model AS350B3 helicopters.
(d) Subject
Joint Aircraft System Component (JASC) Code 6420, Tail rotor
head.
(e) Unsafe Condition
This AD was prompted by an occurrence reported where, during an
inspection of a tail rotor head (TRH) pitch change unit, excessive
play and excessive wear were detected, due to an unwanted rotating
motion and updated airworthiness limitations and maintenance tasks.
The FAA is issuing this AD to detect improper installation of the
pitch change spider nut (nut) and improper alignment of a black
index marking. The unsafe condition, if not addressed, could result
in loss of the TRH pitch change control and consequent loss of
control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) For helicopters with TRH pitch change unit, part number (P/
N) 350A33-2030-00, 350A33-2167-00, or 350A33-2167-01 installed,
within 50 hours time-in-service (TIS) after the effective date of
this AD, inspect the nut for correct installation. If the nut is
missing or loose, before further flight, remove the bearing from the
TRH pitch change unit and do the following:
(i) Inspect the TRH pitch change unit for corrosion. If there is
any corrosion, before further flight, remove the affected part from
service and replace with an airworthy part.
Note 2 to paragraph (g)(1)(i): Airbus Helicopters Mechanical
Repair Manual (MRM) AS350 65-20-00-713, dated March 29, 2017, also
known as Work Card 65-20-00-713 MRM, and Airbus Aircraft Maintenance
Manual (AMM) AS350 65-21-00, 4-9b, dated May 16, 2019, also known as
Task 65-21-00, 4-9 AMM, specify disassembly and reassembly
information for the TRH pitch change unit.
(ii) Inspect for rotation and wear on the faces of the bushes.
For the purposes of this AD, indications of rotation and wear
include tearing, peening, metal pick-up, and hammering. If there is
any rotation or any wear on the faces of the bushes, before further
flight, remove the bushes from service and replace with airworthy
bushes.
(iii) Using 5X or higher power magnification, visually inspect
the rotating plate and the rotating plate threads for damage. For
the purposes of this AD, indications of damage include wear,
deformation, stripping, galling, and corrosion. If there is any
damage on the rotating plate or the rotating plate threads, before
further flight, remove the rotating plate from service and replace
with an airworthy rotating plate.
(iv) Identify the position of the TRH pitch change unit (item a)
and of bearing spacer (item b) by marking a 2 to 5 mm wide black
paint index mark (item C) with black paint as depicted in Figure 1,
Section B-B, of Airbus Helicopters Alert Service Bulletin (ASB) No.
AS350-05.01.03, (ASB AS350-05.01.03 Rev 1), or Airbus Helicopters
ASB No. AS355-05.00.86 (ASB AS355-05.00.86 Rev 1), both Revision 1,
and dated July 8, 2024, as applicable to the model helicopter.
(2) Within 10 hours TIS after the initial marking required by
paragraph (g)(1)(iv) of this AD, visually inspect the alignment of
the marking. An example of a properly aligned marking is depicted in
Figure 1, Section B-B of ASB AS350-05.01.03 Rev 1 and ASB AS355-
05.00.86 Rev 1, as applicable to the model helicopter. If the black
paint index mark (item C) is misaligned, before further flight,
inspect the TRH pitch change unit by accomplishing the actions
required by paragraphs (g)(1)(i) and (ii) of this AD.
(h) Parts Installation Limitations
As of the effective date of this AD, do not install a TRH pitch
change unit P/N 350A33-2030-00, 350A33-2167-00, or 350A33-2167-01 on
any helicopter, unless you do the actions required by paragraphs
(g)(1)(i) and (ii) of this AD before further flight after
installation, and thereafter do the actions required by paragraph
(g)(1)(iii) of this AD at the times specified in paragraph
(g)(1)(iii) of this AD
(i) Credit for Previous Actions
This paragraph provides credit for the initial inspections and
actions required by paragraph (g)(1) of this AD, if those actions
were performed before the effective date of this AD using Airbus
Helicopters ASB No. AS350-05.01.03, or ASB No. AS355-05.00.86, both
Revision 0, and dated December 16, 2021.
(j) Alternative Methods of Compliance (AMOCs)
(1) The Manager, International Validation 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 local Flight
Standards District Office, as appropriate. If sending information
directly
[[Page 58515]]
to the manager of the International Validation Branch, send it to
the attention of the person identified in paragraph (k)(1) of this
AD and email to: <a href="/cdn-cgi/l/email-protection#82c3cfcdc1c2e4e3e3ace5edf4"><span class="__cf_email__" data-cfemail="d6979b999596b0b7b7f8b1b9a0">[email protected]</span></a>.
(2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager
of the local flight standards district office/certificate holding
district office.
(k) Additional Information
(1) For more information about this AD, contact Matthew
Williams, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite
410, Westbury, NY 11590; phone: (316) 946-4134; email:
<a href="/cdn-cgi/l/email-protection#315c5045455954461f451f46585d5d58505c42715750501f565e47"><span class="__cf_email__" data-cfemail="cca1adb8b8a4a9bbe2b8e2bba5a0a0a5ada1bf8caaadade2aba3ba">[email protected]</span></a>.
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (l)(3)
of 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) Airbus Helicopters Alert Service Bulletin (ASB) No. AS350-
05.01.03, Revision 1, dated July 8, 2024.
(ii) Airbus Helicopters ASB No. AS355-05.00.86 Revision 1, dated
July 8, 2024.
(3) For Airbus Helicopters material identified in this AD,
contact Airbus Helicopters, 2701 North Forum Drive, Grand Prairie,
TX 75052; phone: (972) 641-0000 or (800) 232-0323; fax: (972) 641-
3775; website: <a href="http://airbus.com/en/products-services/helicopters/hcare-services/airbusworld">airbus.com/en/products-services/helicopters/hcare-services/airbusworld</a>.
(4) You may view this material at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room 6N
321, Fort Worth, TX 76177. For information on the availability of
this material at the FAA, call (817) 222-5110.
(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 <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#4d2b3f6324233e3d282e392422230d232c3f2c632a223b"><span class="__cf_email__" data-cfemail="cea8bce0a7a0bdbeabadbaa7a1a08ea0afbcafe0a9a1b8">[email protected]</span></a>.
Issued on December 12, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-23100 Filed 12-16-25; 8:45 am]
BILLING CODE 4910-13-P
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