Rule2026-01180
Airworthiness Directives; Airbus Helicopters Deutschland GmbH 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
January 22, 2026
Effective
February 26, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for all Airbus Helicopters Deutschland GmbH (AHD) Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, EC635T2+, and EC135T3 helicopters. This AD was prompted by reports of ruptured and deformed flexible couplings. This AD requires inspecting the axial displacement of the tail rotor drive shaft and, depending on the results, taking corrective actions including inspecting the flexible couplings. This AD also prohibits installing a tail rotor drive shaft unless certain procedures are followed. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 14 (Thursday, January 22, 2026)</title>
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[Federal Register Volume 91, Number 14 (Thursday, January 22, 2026)]
[Rules and Regulations]
[Pages 2681-2683]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-01180]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-0629; Project Identifier MCAI-2023-01183-R;
Amendment 39-23237; AD 2026-02-01]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters Deutschland GmbH
Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Airbus Helicopters Deutschland GmbH (AHD) Model EC135P1, EC135P2,
EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, EC635T2+, and EC135T3
helicopters. This AD was prompted by reports of ruptured and deformed
flexible couplings. This AD requires inspecting the axial displacement
of the tail rotor drive shaft and, depending on the results, taking
corrective actions including inspecting the flexible couplings. This AD
also prohibits installing a tail rotor drive shaft unless certain
procedures are followed. The FAA is issuing this AD to address the
unsafe condition on these products.
DATES: This AD is effective February 26, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of February 26,
2026.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-0629; 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
[[Page 2682]]
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:
<bullet> For European Union Aviation Safety Agency (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#e9a8ad9aa98c889a88c78c9c9b869988c78c9c"><span class="__cf_email__" data-cfemail="47060334072226342669223235283726692232">[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. It is also available at
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2025-0629.
FOR FURTHER INFORMATION CONTACT: Aaron Nguyen, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (817) 222-5134; email: <a href="/cdn-cgi/l/email-protection#b4d5d5c6dbda9ac09adad3c1cdd1daf4d2d5d59ad3dbc2"><span class="__cf_email__" data-cfemail="6f0e0e1d0001411b4101081a160a012f090e0e41080019">[email protected]</span></a>.
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 all AHD Model EC135P1,
EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2, EC135T2+, EC635T2+, and
EC135T3 helicopters. The NPRM was published in the Federal Register on
April 25, 2025 (90 FR 17352). The NPRM was prompted by AD 2023-0197,
dated November 10, 2023 (EASA AD 2023-0197) (also referred to as the
MCAI), issued by EASA, which is the Technical Agent for the Member
States of the European Union. The MCAI advises of reports of ruptured
and deformed flexible couplings, and that investigations determined
that a flexible coupling installed with high axial displacement causes
increased stresses and friction between its sheets. The MCAI states
that this unsafe condition, if not detected and corrected, could lead
to cracks and extensive deformation of flexible couplings and
consequent high vibration of the tail rotor drive shaft, possibly
resulting in reduced control of the helicopter.
In the NPRM, the FAA proposed to require inspecting the axial
displacement of the tail rotor drive shaft and, depending on the
results, taking corrective actions including inspecting the flexible
couplings. The NPRM also proposed to prohibit installing a tail rotor
drive shaft unless certain procedures are followed. The FAA is issuing
this AD to address the unsafe condition on these products.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-0629.
Discussion of Final Airworthiness Directive
Comments
The FAA received no comments on the NPRM or on the determination of
the costs.
Additional Changes Made to This AD
The FAA has revised paragraph (h) of this AD to clarify that where
paragraphs (4) and (6) of EASA AD 2023-0197 specify replacing the
flexible couplings in accordance with the instructions of section 4.1
of the service information referenced, this AD requires replacing the
flexible couplings in accordance with the instructions of sections 4.1
and 4.2 of the service information referenced in EASA AD 2023-0197.
The FAA has also revised paragraph (h) of this AD to clarify that
this AD prohibits installing a tail rotor drive shaft unless certain
procedures are followed, as stated in the Preamble of the NPRM.
Conclusion
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, 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 and any other changes described previously,
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 2023-0197, which specifies a one-time
inspection of the flexible coupling for axial displacement and,
depending on the results, corrective actions. Corrective actions
include replacing both flexible couplings and correcting the axial
displacement, or inspecting the flexible couplings, replacing each
flexible coupling having a discrepancy, and correcting the axial
displacement. For certain flexible couplings not replaced based on the
results of the flexible coupling inspection, EASA AD 2023-0197 requires
replacing the flexible couplings within a longer compliance time. EASA
AD 2023-0197 also prohibits installing a tail rotor drive shaft on any
helicopter unless certain procedures are followed. 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
The MCAI applies to Model EC635 P2+, EC635 P3, EC635 T1, and EC635
T3 helicopters, whereas this AD does not because these models do not
have an FAA type certificate.
Costs of Compliance
The FAA estimates that this AD affects 69 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 AD.
Inspecting both flexible couplings for axial displacement will take
8 work-hours for an estimated cost of $680 per helicopter and $46,920
for the U.S. fleet.
If required, replacing both flexible couplings will take 2 work-
hours, and parts will cost $4,100 for an estimated cost of $4,270 per
helicopter. Replacing one flexible coupling will take 1 work-hour and
parts will cost $2,050 for an estimated cost of $2,135 per flexible
coupling.
If required, correcting the axial displacement of the flexible
couplings will take 5 work-hours for an estimated cost of $425 per
helicopter.
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
[[Page 2683]]
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:
2026-02-01 Airbus Helicopters Deutschland GmbH: Amendment 39-23237;
Docket No. FAA-2025-0629; Project Identifier MCAI-2023-01183-R.
(a) Effective Date
This airworthiness directive (AD) is effective February 26,
2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to Airbus Helicopters Deutschland GmbH (AHD)
Model EC135P1, EC135P2, EC135P2+, EC135P3, EC135T1, EC135T2,
EC135T2+, EC635T2+, and EC135T3 helicopters, certificated in any
category.
Note 1 to paragraph (c): Helicopters with an EC135P3H
designation are Model EC135P3 helicopters and helicopters with an
EC135T3H designation are Model EC135T3 helicopters.
(d) Subject
Joint Aircraft System Component (JASC) Code 6510, Tail Rotor
Drive Shaft.
(e) Unsafe Condition
This AD was prompted by reports of ruptured and deformed
flexible couplings. The FAA is issuing this AD to detect axial
displacement of the tail rotor drive shaft that exceeds allowable
limits. The unsafe condition, if not addressed, could result in
cracks and extensive deformation of flexible couplings, high
vibration of the tail rotor drive shaft, and consequent reduced
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 2023-0197,
dated November 10, 2023 (EASA AD 2023-0197).
(h) Exceptions to EASA AD 2023-0197
(1) Where EASA AD 2023-0197 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(2) Where EASA AD 2023-0197 refers to its effective date, this
AD requires using the effective date of this AD.
(3) Where paragraphs (2) and (6) of EASA AD 2023-0197 state
``new'', this AD requires replacing that text with ``new (zero hours
time-in-service)''.
(4) Where paragraph (4) of EASA AD 2023-0197 states ``any
discrepancy'', for the purpose of this AD, discrepancy may be
indicated by cracks, mechanical damage, deformation, delamination,
corrosion, loose rivets, or damaged surface protection, where these
discrepancies exceed the allowable limits as defined in the material
referenced in EASA AD 2023-0197.
(5) Where paragraph (4) of EASA AD 2023-0197 states ``replace
that flexible coupling'', this AD requires replacing that text with
``replace that flexible coupling with a new (zero hours time-in-
service) flexible coupling''.
(6) Where paragraphs (4) and (6) of EASA AD 2023-0197 state ``in
accordance with the instructions of section 4.1 of the
Accomplishment Procedure of the ASB'', this AD requires replacing
that text with ``in accordance with the instructions of sections 4.1
and 4.2 of the Accomplishment Procedure of the material, referenced
in EASA AD 2023-0197''.
(7) This AD does not adopt the ``Remarks'' section of EASA AD
2023-0197.
(i) No Reporting or Returning of Parts Requirement
Although the material referenced in EASA AD 2023-0197 specifies
to submit certain information and to send parts to the manufacturer,
this AD does not require those actions.
(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) of
this AD and email to: <a href="/cdn-cgi/l/email-protection#95d4d8dad6d5f3f4f4bbf2fae3"><span class="__cf_email__" data-cfemail="d7969a989497b1b6b6f9b0b8a1">[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) Additional Information
For more information about this AD, contact Aaron Nguyen,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (817) 222-5134; email:
<a href="/cdn-cgi/l/email-protection#e28383908d8ccc96cc8c85979b878ca2848383cc858d94"><span class="__cf_email__" data-cfemail="cfaeaebda0a1e1bbe1a1a8bab6aaa18fa9aeaee1a8a0b9">[email protected]</span></a>.
(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 the AD specifies otherwise.
(i) European Union Aviation Safety Agency (EASA) AD 2023-0197,
dated November 10, 2023.
(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#8ccdc8ffcce9edffeda2e9f9fee3fceda2e9f9"><span class="__cf_email__" data-cfemail="98d9dcebd8fdf9ebf9b6fdedeaf7e8f9b6fded">[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#87e1f5a9eee9f4f7e2e4f3eee8e9c7e9e6f5e6a9e0e8f1"><span class="__cf_email__" data-cfemail="5335217d3a3d20233630273a3c3d133d3221327d343c25">[email protected]</span></a>.
Issued on January 14, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-01180 Filed 1-21-26; 8:45 am]
BILLING CODE 4910-13-P
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