DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-0617; Project Identifier MCAI-2024-00331-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 adopt a new airworthiness directive (AD)
for all Airbus Helicopters Model AS-365N2, AS 365 N3, EC 155B, EC155B1,
SA-365N, and SA-365N1 helicopters. This proposed AD was prompted by
reports of loss of tightening torque between the upper ball bearing end
and the main rotor (MR) servo-control. This proposed AD would require
inspecting the tightening torque and, depending on the results, taking
corrective action. This proposed AD would also require reporting
information. These actions are specified in a European Union Aviation
Safety Agency (EASA) AD, which is proposed for incorporation by
reference. The FAA is proposing this AD to address the unsafe condition
on these products.

DATES: The FAA must receive comments on this NPRM by May 30, 2025.

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-2025-0617; 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:

For EASA material identified in this proposed AD, contact
EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221
8999 000; email: ADs@easa.europa.eu; website: easa.europa.eu. You may
find this material on the EASA website at ad.easa.europa.eu. It is also
available at regulations.gov under Docket No. FAA-2025-0617.

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: Peter Schmitt, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (206) 231-3377; email: peter.a.schmitt@faa.gov.

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 the ADDRESSES section. Include "Docket No. FAA-2025-0617;
Project Identifier MCAI-2024-00331-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
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 Peter
Schmitt, 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 EASA AD 2024-0110, dated June 6, 2024 (EASA
AD 2024-0110) (also referred to as the MCAI), to correct an unsafe
condition on Airbus Helicopters Model SA 365 N, SA 365 N1, AS 365 N2,
AS 365 N3, EC 155 B, and EC 155 B1 helicopters. The MCAI states two
occurrences were reported of loss of tightening torque between the
upper ball bearing end and the MR servo-control, which in one
occurrence, led to the disconnection of these two parts. The MCAI
further states that the investigation is still on-going to determine
the root cause. EASA considers this MCAI an interim action and further
action may follow. This condition, if not addressed, could result in
disconnection between the upper ball bearing end and the MR servo-
control, and consequent loss control of the helicopter.

The FAA is proposing this AD to address the unsafe condition on
these products. You may examine the MCAI in the AD docket at
regulations.gov under Docket No. FAA-2025-0617.

Material Incorporated by Reference Under 1 CFR Part 51

EASA AD 2024-0110 requires a one-time check of the torque on each
nut connecting the upper ball bearing end to all three MR servo-
controls and, depending on the results, taking corrective actions,
which include applying torque, lockwire, and sealing compound to the
upper ball bearing end of the MR servo-control, inspecting the ball
bearing end of the MR-servo control, replacing a ball bearing end,
inspecting the upper end fitting of the MR-servo control, and replacing
the MR servo-control. EASA AD 2024-0110 also requires reporting the
inspection results (including no findings) to AH [Airbus Helicopters].

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 issuing this NPRM after
determining that the unsafe condition described previously is likely to
exist or develop on other products of the same type designs.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in EASA AD 2024-0110, described previously, as incorporated by
reference, except for any differences identified as exceptions in the
regulatory text of this proposed AD and except as discussed under
"Differences Between this Proposed AD and the MCAI."

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 2024-0110 by reference in the FAA
final rule. This proposed AD would, therefore, require compliance with
EASA AD 2024-0110 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 2024-0110 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 2024-
0110. Material required by EASA AD 2024-0110 for compliance will be
available at regulations.gov under Docket No. FAA-2025-0617 after the
FAA final rule is published.

Differences Between This Proposed AD and the MCAI

The MCAI, as well as the material referenced in the MCAI, refer to
the "torque inspection" as a "check." In an FAA AD, a "check" may
be done by the owner/operator (pilot) holding at least a private pilot
certificate provided certain criteria are met. The authorization for a
"check" in an FAA AD is an exception to the FAA's standard
maintenance regulations and the criteria is not met in this proposed
AD. Accordingly, this proposed AD would require those actions be
accomplished by persons authorized under 14 CFR 43.3.

Interim Action

The FAA considers this proposed AD an interim action. If final
action is later identified, the FAA might consider further rulemaking then.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 63 helicopters of U.S. Registry. Labor rates are estimated at
$85 per work-hour. Based on these numbers, the FAA estimates the
following costs to comply with this proposed AD.

Inspecting the tightening torque of the upper ball bearing end of
each MR servo control would take 1 work-hour for an estimated cost of
$255 per helicopter (three MR servo-controls per helicopter) and
$16,065 for the U.S. fleet.

Reporting the results of the inspection would take 1 work-hour for
an estimated cost of $85 per helicopter and $5,355 for the U.S. fleet.

If required, applying torque, lock-wire, and sealing compound to
the upper ball bearing end of each MR servo-control would take .5 work-
hour and parts would cost a nominal amount for an estimated cost of
$127.50 per helicopter (for up to three MR servo-controls per
helicopter).

If required, inspecting the threads of a ball bearing end would
take 1 work-hour for an estimated cost of $85 per ball bearing end.
Depending on the results, replacing a ball bearing end would take 1
work-hour and parts
would cost $1,299 for an estimated cost of $1,384 per ball bearing end.

If required, inspecting the threads of an upper end fitting would
take 1 work-hour for an estimated cost of $85 per upper-end fitting.
Depending on the results, replacing an MR servo-control would take 1
work-hour and parts would cost $41,039 for an estimated cost of $41,124
per MR servo-control.

Paperwork Reduction Act

A federal agency may not conduct or sponsor, and a person is not
required to respond to, nor shall a person be subject to a penalty for
failure to comply with a collection of information subject to the
requirements of the Paperwork Reduction Act unless that collection of
information displays a currently valid OMB Control Number. The OMB
Control Number for this information collection is 2120-0056. Public
reporting for this collection of information is estimated to take
approximately 1 hour per response, including the time for reviewing
instructions, searching existing data sources, gathering and
maintaining the data needed, and completing and reviewing the
collection of information. All responses to this collection of
information are mandatory. Send comments regarding this burden estimate
or any other aspect of this collection of information, including
suggestions for reducing this burden, to: Information Collection
Clearance Officer, Federal Aviation Administration, 10101 Hillwood
Parkway, Fort Worth, TX 76177-1524.

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: