Proposed Rule2025-23101
Airworthiness Directives; Airbus Helicopters
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
December 17, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Model AS355E, AS 355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters. This proposed AD was prompted by a report of a structural crack in the vertical attachment spar of the tail fin. This proposed AD would require repetitive inspections of certain vertical upper fin spars and, depending on the results, corrective action. This proposed AD would also prohibit installing certain upper fin assemblies. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
<html>
<head>
<title>Federal Register, Volume 90 Issue 240 (Wednesday, December 17, 2025)</title>
</head>
<body><pre>
[Federal Register Volume 90, Number 240 (Wednesday, December 17, 2025)]
[Proposed Rules]
[Pages 58519-58521]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-23101]
[[Page 58519]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-5039; Project Identifier MCAI-2024-00426-R]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for all Airbus Helicopters Model AS355E, AS 355-F, AS 355-F1, AS355F2,
AS355N, and AS355NP helicopters. This proposed AD was prompted by a
report of a structural crack in the vertical attachment spar of the
tail fin. This proposed AD would require repetitive inspections of
certain vertical upper fin spars and, depending on the results,
corrective action. This proposed AD would also prohibit installing
certain upper fin assemblies. 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-2025-5039; 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 EASA material identified in this AD, contact EASA,
Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999
000; email: <a href="/cdn-cgi/l/email-protection#cf8e8bbc8faaaebcaee1aababda0bfaee1aaba"><span class="__cf_email__" data-cfemail="0342477043666270622d6676716c73622d6676">[email protected]</span></a>; website: easa.europa.eu. You may find
the EASA material on the EASA website at ad.easa.europa.eu.
<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: Yves Petiote, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (202) 975-4867; email: <a href="/cdn-cgi/l/email-protection#f9808f9c8ad7899c8d90968d9cb99f9898d79e968f"><span class="__cf_email__" data-cfemail="136a6576603d6376677a7c6776537572723d747c65">[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 using a method listed
under the ADDRESSES section. Include ``Docket No. FAA-2025-5039;
Project Identifier MCAI-2024-00426-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 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
<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 Yves
Petiote, 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
EASA, which is the Technical Agent for the Member States of the
European Union, has issued a series of ADs, the most recent being EASA
AD 2023-0154R1, dated July 19, 2024 (EASA AD 2023-0154R1) (also
referred to as ``the MCAI''), to correct an unsafe condition on all
Airbus Helicopters Model AS 355 E, AS 355 F, AS 355 F1, AS355 F2, AS355
N, and AS 355 NP helicopters. The MCAI advises of a report of a
structural crack (not a complete failure) in the vertical attachment
spar of the tail fin.
The MCAI states that the unsafe condition, if not addressed, may
lead to in-flight separation of the upper part of the vertical fin,
which could result in loss of control of the helicopter. The FAA is
proposing this AD to address the unsafe condition on these products.
EASA has issued related EASA AD 2024-0139, dated July 12, 2024
(EASA AD 2024-0139), for these same model helicopters as well as
certain Model AS350B3 helicopters, to address cracking in a different
area of the upper fin spar as well as the fin's front attachment
screws. The FAA issued AD 2025-24-04, Amendment 39-23199 (90 FR 56679,
December 8, 2025) (AD 2025-24-04), to address EASA AD 2024-0139. This
proposed AD includes actions that would be contingent on some of the
required actions in AD 2025-24-04.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-5039.
Material Incorporated by Reference Under 1 CFR Part 51
FAA reviewed EASA AD 2023-0154R1, which specifies procedures for
removing the tail gear box (TGB) fairing and the rear fairing from the
tail boom, cleaning, and inspecting the right-hand external side around
the two top screws of certain upper fin spars for a crack. EASA AD
2023-0154R1 also specifies procedures for conducting repetitive
borescope inspections of that upper fin spar area for a crack or
repeating the initial inspection as an alternative. Additionally, EASA
AD 2023-0154R1 specifies accomplishing the inspections prior to and
after maintenance flights that exceed the reduced V<INF>NE</INF>
(Velocity Never Exceed) required by EASA AD 2024-0139 and after each
other flight that exceeds the reduced V<INF>NE</INF> required
[[Page 58520]]
by EASA AD 2024-0139. Depending on the results of an inspection, EASA
AD 2023-0154R1 specifies procedures for marking the two top right-hand
screw ends or replacing the upper fin. EASA AD 2023-0154R1 further
specifies that installing an upper fin assembly part number (P/N)
355A14-0522-1751 constitutes terminating action for its repetitive
inspection requirements and prohibits installing certain upper fin
assemblies on any helicopter. 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 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 referenced above. The FAA is proposing this AD after
evaluating all known relevant information and 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 accomplishing the actions specified
in EASA AD 2023-0154R1, described previously, as incorporated by
reference, except for any differences identified as exceptions in the
regulatory text of this proposed AD. See ``Differences Between this AD
and the MCAI'' for a discussion of these differences.
Differences Between This Proposed AD and the MCAI
Where the MCAI defines an affected part as those listed in any
revision of the manufacturer's service information, this proposed AD
would define an affected part as those listed in specific versions of
the manufacturer's service information and would include upper fin
assemblies for which the P/N cannot be determined.
Explanation of Required Compliance Information
In the FAA's ongoing efforts to improve the efficiency of the AD
process, the FAA developed a process to use some civil aviation
authority (CAA) ADs as the primary source of information for compliance
with requirements for corresponding FAA ADs. The FAA has been
coordinating this process with manufacturers and CAAs. As a result, the
FAA proposes to incorporate EASA AD 2023-0154R1 by reference in the FAA
final rule. This proposed AD would, therefore, require compliance with
EASA AD 2023-0154R1 in its entirety through that incorporation, except
for any differences identified as exceptions in the regulatory text of
this proposed AD. Using common terms that are the same as the heading
of a particular section in EASA AD 2023-0154R1 does not mean that
operators need comply only with that section. For example, where the AD
requirement refers to ``all required actions and compliance times,''
compliance with this AD requirement is not limited to the section
titled ``Required Action(s) and Compliance Time(s)'' in EASA AD 2023-
0154R1. Material referenced in EASA AD 2023-0154R1 for compliance will
be available at <a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2025-5039 after
the FAA final rule is published.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 177 helicopters of U.S. registry. Labor rates are estimated at
$85 per hour. Based on these numbers, the FAA estimates the following
costs to comply with this proposed AD.
Initial cleaning and inspection of the vertical fin spar and, if
necessary, application of a paint mark on the top two right-hand screw
ends would take 2.5 work-hours for an estimated cost of $213 per
helicopter and $37,701 for the U.S. fleet.
Repetitive borescope inspection of the upper fin spar would take
0.5 work-hour for an estimated cost of $43 per helicopter and up to
$7,611 for the U.S. fleet, per inspection cycle. Alternatively,
repeating the initial inspection would take 2.5 work-hours for an
estimated cost of $213 per helicopter and up to $37,701 for the U.S.
fleet, per inspection cycle.
If required, removing the upper fin from service and installing
upper fin assembly P/N 355A14-0522-1751 to modify the upper fin would
take 40 work-hours and parts would cost $25,360 for an estimated cost
of $28,760 per helicopter.
The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some 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
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]
2. The FAA amends Sec. 39.13 by adding the following new
airworthiness directive:
[[Page 58521]]
Airbus Helicopters: Docket No. FAA-2025-5039; Project Identifier
MCAI-2024-00426-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by February 2, 2026.
(b) Affected ADs
This AD affects AD 2025-24-04, Amendment 39-23199 (90 FR 56679,
December 8, 2025) (AD 2025-24-04).
(c) Applicability
This AD applies to Airbus Helicopters Model AS355E, AS 355-F, AS
355-F1, AS355F2, AS355N, and AS355NP helicopters, certificated in
any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 5531, Vertical
Stabilizer, Spar/Rib Structure.
(e) Unsafe Condition
This AD was prompted by a report of a structural crack in the
vertical attachment spar of the tail fin. The FAA is issuing this AD
to address cracking in the upper fin spar. This condition could lead
to in-flight separation of the upper part of the vertical fin, which
could result in loss of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Requirements
Except as specified in paragraphs (h) and (i) of this AD: Comply
with all required actions and compliance times specified in, and in
accordance with, European Union Aviation Safety Agency AD 2023-
0154R1, dated July 19, 2024 (EASA AD 2023-0154R1).
(h) Exceptions to EASA AD 2023-0154R1
(1) Where EASA AD 2023-0154R1 defines an ``affected part,'' this
AD requires replacing that text with ``an upper fin assembly having
a part number (P/N) identified in the Applicability, Accomplishment
Procedure, of Airbus Helicopters Emergency Alert Service Bulletin
EASB AS355-05-00-0001, Issue 001, dated July 25, 2023, or Issue 002,
dated July 9, 2024, or an upper fin assembly having a P/N that
cannot be determined.
Note 1 to paragraph (h)(1): MOD 0720098 involves installing a
new upper fin that has a reinforced fin spar (P/N 355A14-0522-1751)
that is not affected by this AD. Airbus Helicopters Alert Service
Bulletin No. AS355-55.00.18, Revision 1, dated June 6, 2024,
contains information regarding MOD 0720098.
(2) Where EASA AD 2023-0154R1 refers to August 3, 2023 (the
effective date of EASA AD 2023-0154, dated July 27, 2023), this AD
requires using the effective date of this AD.
(3) Where EASA AD 2023-0154R1 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(4) Where paragraph (3) of EASA AD 2023-0154R1 specifies
``following the Rotorcraft Flight Manual (RFM) amendment as required
by paragraph (1) or (2) of EASA AD 2024-0139, as applicable, it is
allowed to exceed the temporary reduced Vne during a maintenance
flight'', this AD requires replacing that text with ``following the
Rotorcraft Flight Manual (RFM) amendment required by AD 2025-24-04,
it is allowed to exceed the temporary reduced V<INF>NE</INF> during
a flight to perform an operational check as specified in 14 CFR
91.407''.
(5) Where paragraphs (3.1), (3.2), and (3.3) of EASA AD 2023-
0154R1 specify ``maintenance flight'', this AD requires replacing
that text with ``flight to perform an operational check as specified
in 14 CFR 91.407''.
(6) Where paragraph (4) of EASA AD 2023-0154R1 specifies ``if,
following the RFM amendment as required by paragraph (1) or (2) of
EASA AD 2024-0139, as applicable, the temporary reduced Vne is
exceeded on a helicopter'', this AD requires replacing that text
with ``if, following the RFM amendment required by AD 2025-24-04,
the temporary reduced V<INF>NE</INF> is exceeded on a helicopter''.
(7) Where Note 1 of EASA AD 2023-0154R1 specifies ``It is
allowed to temporarily remove the RFM amendment and the placard, as
required by paragraph (1) or (2) of EASA AD 2024-0139, as
applicable, to allow maintenance flight(s) during which the
temporarily reduced Vne may be exceeded'', this AD requires
replacing that text with ``It is allowed to temporarily remove the
RFM amendment and the placard required by AD 2025-24-04 to allow
flight(s) to perform an operational check as specified in 14 CFR
91.407, during which the temporarily reduced V<INF>NE</INF> may be
exceeded''.
Note 2 to paragraph (h)(7): Refer to AD 2025-24-04 for
requirements pertaining to exceeding V<INF>NE</INF> 110 kts. Airbus
Helicopters Emergency Alert Service Bulletin EASB AS355-05-00-0001,
Issue 002, dated July 9, 2024, also contains information regarding
exceeding Vne 110 kts.
(8) Instead of complying with paragraph (6) of EASA AD 2023-
0154R1, if there is a crack as a result of the inspections required
by paragraphs (1) through (4) of EASA AD 2023-0154R1, this AD
requires, before further flight, removing the upper fin from service
and installing upper fin assembly P/N 355A14-0522-1751 in accordance
with paragraph (7) and Note 2 of EASA AD 2023-0154R1.
(9) Where Note 2 of EASA AD 2023-0154R1 specifies ``paragraph
(12) of EASA AD 2024-0139'', this AD requires replacing that text
with ``AD 2025-24-04''.
(10) This AD does not adopt the ``Remarks'' section of EASA AD
2023-0154R1.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2023-0154R1
specifies to submit certain information to the manufacturer, this AD
does not include that requirement.
(j) Special Flight Permits
Special flight permits are prohibited.
(k) 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 to the manager of the International Validation Branch, send
it to the attention of the person identified in paragraph (l)(1) of
this AD and email to: <a href="/cdn-cgi/l/email-protection#ca8b8785898aacababe4ada5bc"><span class="__cf_email__" data-cfemail="f8b9b5b7bbb89e9999d69f978e">[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.
(l) Related Information
(1) For more information about this AD, contact Yves Petiote,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (202) 975-4867; email:
<a href="/cdn-cgi/l/email-protection#374e415244194752435e5843527751565619505841"><span class="__cf_email__" data-cfemail="fb828d9e88d58b9e8f92948f9ebb9d9a9ad59c948d">[email protected]</span></a>.
(2) Airbus Helicopters material identified in this AD that is
not incorporated by reference is available at the address specified
in paragraph (m)(3) of this AD.
(m) 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 this AD specifies otherwise.
(i) European Union Aviation Safety Agency (EASA) AD 2023-0154R1,
dated July 19, 2024.
(ii) [Reserved]
(3) For EASA material identified in this AD, contact EASA,
Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999
000; email: <a href="/cdn-cgi/l/email-protection#f3b2b780b396928092dd9686819c8392dd9686"><span class="__cf_email__" data-cfemail="4001043300252133216e2535322f30216e2535">[email protected]</span></a>; website: easa.europa.eu. You may
find the EASA material on the EASA website at ad.easa.europa.eu.
(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#670115490e0914170204130e0809270906150649000811"><span class="__cf_email__" data-cfemail="264054084f4855564345524f4948664847544708414950">[email protected]</span></a>.
Issued on December 12, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-23101 Filed 12-16-25; 8:45 am]
BILLING CODE 4910-13-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on December 17, 2025.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.