[Federal Register Volume 90, Number 233 (Monday, December 8, 2025)]
[Rules and Regulations]
[Pages 56679-56682]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-22234]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-1735; Project Identifier MCAI-2024-00408-R;
Amendment 39-23199; AD 2025-24-04]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2021-20-
16, which applied to all Airbus Helicopters Model AS355E, AS 355-F, AS
355-F1, AS355F2, AS355N, and AS355NP helicopters and certain Model AS
350B3 helicopters. AD 2021-20-16 required repetitive cleaning and
visual and detailed inspections of the right-hand side of the vertical
fin spar and vertical fin upper attachments for discrepancies
(cracking) with corrective action, if necessary. Since the FAA issued
AD 2021-20-16, Airbus Helicopters developed a modification of the upper
fin assembly. This AD requires the same actions as AD 2021-20-16 and
replacement of the upper fin assembly with a modified upper fin
assembly, which constitutes a terminating action for the repetitive
inspections. The FAA is issuing this AD to address the unsafe condition
on these products.
DATES: This AD is effective January 12, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of January 12,
2026.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2025-1735; 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, the mandatory continuing airworthiness
information (MCAI), 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 European Union Aviation Agency (EASA) material
identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668
Cologne, Germany; phone: +49 221 8999 000; email: [email protected];
website: easa.europa.eu. You may find the EASA material on the EASA
website at ad.easa.europa.eu.
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. It is also available at
regulations.gov under Docket No. FAA-2025-1735.
FOR FURTHER INFORMATION CONTACT: Steven Warwick, Aviation Safety
Engineer, FAA, 1600 Stewart Ave., Suite 410, Westbury, NY 11590; phone:
(817) 222-5225; email: [email protected].
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2021-20-16, Amendment 39-21754 (86 FR
57550, dated October 18, 2021) (AD 2021-20-16). AD 2021-20-16 applied
to Airbus Helicopters Model AS355E, AS 355-F, AS 355-F1, AS355F2,
AS355N, and AS355NP helicopters, all serial numbers, and Model AS 350B3
helicopters, all serial numbers except those that have Airbus
Helicopters Modification 073148 in production. AD
[[Page 56680]]
2021-20-16 required repetitive cleaning and detailed inspections for
cracking of the vertical fin spar and vertical fin upper attachments,
and corrective action if necessary. The FAA issued AD 2021-20-16 to
address cracking in the spar of the upper part of the vertical fin and
fractures in the front attachment screws.
The NPRM was published in the Federal Register on August 21, 2025
(90 FR 40786). The NPRM was prompted by EASA AD 2024-0139, dated July
12, 2024 (EASA AD 2024-0139) (also referred to as the MCAI), issued by
EASA, which is the Technical Agent for the Member States of the
European Union. The MCAI states that after a further occurrence of a
crack on a Model AS355NP helicopter, EASA concluded there was a need to
temporarily reduce the never-exceed-speed (VNE) for all
AS355 helicopters. In addition, Airbus Helicopters developed a
reinforced upper fin assembly and published service information that
provides instructions for this modification. EASA AD 2024-0139 retains
the repetitive inspections and VNE limitations in its
previous ADs and also requires modification of the helicopter with the
reinforced upper fin assembly, which is the terminating action for the
inspections and limitations.
In the NPRM, the FAA proposed to require the same actions as AD
2021-20-16 and proposed to require replacement of the upper fin
assembly with a modified upper fin assembly, which constitutes a
terminating action for the repetitive inspections and limitations.
The FAA is issuing this AD to address cracking in the upper fin
spar and fracturing of the front attachment screws. The unsafe
condition, if not addressed, could result in in-flight separation of
the upper part of the vertical fin and consequent loss of control of
the helicopter.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2025-1735.
Discussion of Final Airworthiness Directive
Comments
The FAA received a comment from one individual who disagreed with
the practice of relying on manufacturer-issued and foreign regulatory
documents that are not fully integrated into the rule text. The
following presents the comment received on the NPRM and the FAA's
response to the comment.
Request To Incorporate Requirements Directly Into the AD
The individual commenter requested that the FAA AD become a stand-
alone document. The individual commented that relying on EASA's AD as
the base document, and providing exceptions in the FAA's rule, makes
the requirements unclear and confusing. The commenter further stated
that the AD should comply with plain language guidelines in FAA Order
1000.36.
The FAA disagrees with the request. 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.
This AD incorporates EASA AD 2024-0139 by reference. Incorporating
information by reference is a common method of federal rulemaking, that
is explicitly permitted under 1 CFR 51. As stated in the Incorporation
by Reference Handbook, June 2023 Edition, incorporation of relevant,
usually technical information (such as the MCAI) promotes efficiency.
The commenter did not identify a provision of FAA Order 1000.36A that
the IBR practice violates, and none are apparent to the FAA. The
complete inspection method, measurable thresholds, and corrective
actions are included in EASA AD 2024-0139 and the material referenced
in EASA AD 2024-0139, which are available at regulations.gov under the
Docket No. for this AD, FAA-2025-1735. The FAA has not changed this AD
in this regard.
Conclusion
These products have been approved by the CAA 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, that authority
has notified the FAA of the unsafe condition described in the MCAI
referenced above. 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 EASA AD 2024-0139, which specifies procedures for
amending the rotorcraft flight manual (RFM) and installing a placard to
add a speed limitation. EASA AD 2024-0139 allows exceeding the speed
limitation on certain maintenance flights and specifies accomplishing
an inspection after each flight where the speed is exceeded. EASA AD
2024-0139 also requires repetitively inspecting the right-hand external
side around the two top screws of certain upper fin spars for a crack.
EASA AD 2024-0139 specifies that installing an upper fin assembly P/N
355A14-0522-1751 constitutes terminating action for the repetitive
inspection requirements and the speed limitations. Lastly, EASA AD
2024-0139 prohibits installing affected 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.
Differences Between This AD and the MCAI Referenced Material
While the material referenced in EASA AD 2024-0139 requires
accomplishing dye penetrant inspections (DPI), this AD requires a DPI
if the affected part has previously been inspected by a DPI method;
otherwise, this AD requires a fluorescent penetrant inspection (FPI).
Where EASA AD 2024-0139 and the material referenced in EASA AD
2024-0139 specifies contacting Airbus Helicopters for repair
instructions, this AD requires using a method approved by the FAA,
EASA, or Airbus Helicopters' EASA Design Organization Approval.
EASA AD 2024-0139 requires informing all flight crew and operating
the helicopter accordingly. However, this AD would not specifically
require this action because 14 CFR 91.9 requires that no person may
operate a civil aircraft without complying with the operating
limitations specified in the RFM. Therefore, including a requirement in
this AD to operate the helicopter according to the revised RFM would be
redundant and unnecessary. Further, compliance with such a requirement
in an AD would be impracticable to demonstrate or track on an ongoing
basis; therefore, a requirement to operate the airplane in such a
manner would be unenforceable.
EASA AD 2024-0139 allows a pilot to perform some actions, and this
AD does not.
Costs of Compliance
The FAA estimates that this AD affects 650 helicopters of U.S.
registry.
[[Page 56681]]
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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Amend the RFM and install a placard... 1 work-hour x $85 per $25 $110 $71,500
hour = $85.
Clean and inspect the vertical fin 2.5 work-hour x $85 per 0 213 138,450
spar. hour = $213.
Modify the upper fin spar............. 19 work-hour x $85 per 25,360 26,975 17,533,750
hour = $1,615.
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The FAA estimates the following costs to do any repairs or
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 this repair.
On-Condition Costs
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Cost per
Action Labor cost Parts cost product
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Perform a DPI or FPI on the upper fin spar.... 1 work-hours x $85 per hour = $0 $85
$85.
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The extent of damage found during the required inspection of the
vertical fin spar could vary significantly from helicopter to
helicopter. The agency has no way of determining how much damage may be
found during these inspections, the cost to repair damaged parts of
each helicopter, or the number of helicopters that might need these
repairs.
The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some 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
The FAA has determined that 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:
0
a. Removing Airworthiness Directive 2021-20-16, Amendment 39-21754 (86
FR 57550, dated October 18, 2021); and
0
b. Adding the following new airworthiness directive:
2025-24-04 AIRBUS HELICOPTERS: Amendment 39-23199; Docket No. FAA-
2025-1735; Project Identifier MCAI-2024-00408-R.
(a) Effective Date
This airworthiness directive (AD) is effective January 12, 2026.
(b) Affected ADs
This AD replaces AD 2021-20-16, Amendment 39-21754 (86 FR 57550,
dated October 18, 2021).
(c) Applicability
This AD applies to Airbus Helicopters Model AS 350B3, AS355E, AS
355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters,
certificated in any category, as identified in European Union
Aviation Safety Agency AD 2024-0139, dated July 12, 2024 (EASA AD
2024-0139).
(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 upper tail fin and fractures in its
two front attachment screws. The FAA is issuing this AD to address
cracking in the upper fin spar and fracturing of the front
attachment screws. The unsafe condition, if not addressed, could
result in in-flight separation of the upper part of the vertical fin
and consequent 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, EASA AD 2024-0139.
[[Page 56682]]
(h) Exceptions to EASA AD 2024-0139
(1) Where EASA AD 2024-0139 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(2) Where EASA AD 2024-0139 refers to its effective date or to
any of the dates listed in paragraphs (h)(2)(i) through (iv) of this
AD, this AD requires using the effective date of this AD.
(i) July 12, 2017 (the effective date of EASA AD 2017-0114,
dated June 28, 2017).
(ii) April 23, 2021 (the effective date of EASA AD 2021-0099,
dated April 9, 2021).
(iii) April 14, 2023 (the effective date of EASA AD 2023-0075,
dated April 7, 2023).
(iv) May 18, 2023 (the effective date of EASA AD 2023-0089,
dated May 4, 2023).
(3) Where paragraph (1) of EASA AD 2024-0139 specifies to inform
all flight crew and operate the helicopter accordingly, this AD does
not require those actions as those actions are already required by
existing FAA operating regulations (see 14 CFR 91.505 and 14 CFR
135.21).
(4) Although the material referenced in EASA AD 2024-0139 allows
some actions to be performed by a pilot, this AD does not.
(5) Where the material referenced in EASA AD 2024-0139 states
``if you are not sure'', this AD requires replacing that text with
``to confirm suspected cracks (scratch, line, misalignment, etc.)''.
(6) Where the material referenced in EASA AD 2024-0139 states to
do a dye-penetrant inspection (DPI), this AD requires the actions in
paragraph (h)(6)(i), (ii), or (iii) of this AD, as applicable:
(i) If the right-hand (RH) side of the spar (a) has previously
been inspected by a DPI method, accomplish a DPI of the RH side of
the spar (a).
(ii) If the RH side of the spar (a) has not previously been
inspected by a DPI, accomplish a fluorescent penetrant inspection
(FPI) of the RH-hand side of the spar (a), instead of a DPI.
(iii) If you cannot determine whether the RH side of the spar
(a) has previously been inspected by a DPI, clean all surfaces to be
inspected and accomplish an FPI of the RH side of the spar (a)
instead of a DPI.
Note 1 to paragraph (h)(6)(iii): Work Card 20-02-09-101 (MTC)
contains DPI information related to this AD.
Note 2 to paragraph (h)(6)(iii): When entering compliance with
the applicable paragraph of the AD into the helicopter maintenance
records, explicitly documenting that a dye penetrant inspection was
performed improves the accuracy of maintenance records regarding use
of dye penetrant inspection dye.
(7) Where the material referenced in EASA AD 2024-0139 refers to
damage, for this AD, damage is defined as looseness, corrosion,
broken or missing lockwire, loss of protective surface finish,
deformation, fracture, crack, or nick.
(8) Where paragraph (8) of EASA AD 2024-0139 states
``maintenance flight'', this AD requires replacing that text with
``flight to perform an operational check as specified in 14 CFR
91.407''.
(9) Where paragraph (10) of EASA AD 2024-0139 and the material
referenced in EASA AD 2024-0139 specify contacting Airbus
Helicopters for repair instructions, this AD requires using a repair
method approved by the FAA, EASA, or Airbus Helicopters' EASA Design
Organization Approval (DOA). If approved by the DOA, the approval
must include the DOA-authorized signature.
(10) Where the material referenced in EASA AD 2024-0139
specifies to discard parts, this AD requires removing those parts
from service.
(11) Where paragraph (16) of EASA AD 2024-0139 only allows
credit for the initial actions in paragraphs (4) through (9) of EASA
AD 2024-0139, this AD allows credit for any action in paragraphs (4)
through (9) of EASA AD 2024-0139.
(12) This AD does not adopt the ``Remarks'' section of EASA AD
2024-0139.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2024-0139 specifies
to submit certain information to the manufacturer, this AD does not
require that action.
(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 to the manager of the International Validation Branch, send
it to the attention of the person identified in paragraph (k) of
this AD and email to: [email protected].
(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
For more information about this AD, contact Steven Warwick,
Aviation Safety Engineer, FAA, 1600 Stewart Ave., Suite 410,
Westbury, NY 11590; phone: (817) 222-5225; email:
[email protected].
(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) European Union Aviation Safety Agency (EASA) AD 2024-0139,
dated July 12, 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: [email protected]; 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 Pkwy., 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 www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].
Issued on November 19, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-22234 Filed 12-5-25; 8:45 am]
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