DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-1018; Project Identifier MCAI-2021-00902-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 AS332L2 and EC225LP helicopters. This
proposed AD was prompted by a report of loss of tightening torque on
the nut that attaches the tail gear box (TGB) bevel wheel. This
proposed AD would require repetitive inspections (measurements) of the
angular clearances of the TGB, and, depending on the findings,
replacement of the TGB with a serviceable TGB, as specified in a
European Union Aviation Safety Agency (EASA) AD, which is proposed for
incorporation by reference (IBR). This proposed AD would also provide
terminating action for certain repetitive inspections. The FAA is
proposing this AD to address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by January 18,
2022.

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 https://www.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.
For EASA material that is proposed for IBR in this AD, contact
EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; telephone +49 221
8999 000; email ADs@easa.europa.eu; internet www.easa.europa.eu. You
may find the EASA material on the EASA website at https://ad.easa.europa.eu.
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. This material is also
available at https://www.regulations.gov by searching for and locating
Docket No. FAA-2021-1018.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-1018; 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 EASA AD,
any comments received, and other information. The street address for
Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Andrea Jimenez, Aerospace Engineer,
COS Program Management Section, Operational Safety Branch, Compliance &
Airworthiness Division, FAA, 1600 Stewart Ave., Suite 410, Westbury, NY
11590; telephone (516) 228-7330; email andrea.jimenez@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 ADDRESSES. Include ``Docket No. FAA-2021-1018; Project Identifier
MCAI-2021-00902-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
https://www.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
Andrea Jimenez, Aerospace Engineer, COS Program Management Section,
Operational Safety Branch, Compliance & Airworthiness Division, FAA,
1600 Stewart Ave., Suite 410, Westbury, NY 11590; telephone (516) 228-
7330; email andrea.jimenez@faa.gov. Any commentary that the FAA
receives that is not specifically designated as CBI will be placed in
the public docket for this rulemaking.

Background

The EASA, which is the Technical Agent for the Member States of the
European Union, has issued EASA AD 2021-0184R1, dated October 8, 2021
(EASA AD 2021-0184R1), to correct an unsafe condition for Airbus
Helicopters, formerly Eurocopter, Eurocopter France, Aerospatiale,
Model AS 332 L2 and EC 225 LP helicopters, all serial numbers.
This proposed AD was prompted by a report of loss of tightening
torque on the nut that attaches the TGB bevel wheel. Additionally, the
subsequent investigation highlighted that loss of the tightening torque
might lead to degradation of the splines between the
tail rotor shaft and the TGB bevel wheel. The investigation is still
on-going to identify the root cause of the tightening torque loss. The
FAA is proposing this AD to address loss of tightening torque on the
nut that attaches the TGB bevel wheel, which, if not corrected, could
lead to structural failure of the TGB drive, resulting in reduced, or
loss of, control of the helicopter. See EASA AD 2021-0184R1 for
additional background information.

Related Service Information Under 1 CFR Part 51

EASA AD 2021-0184R1 requires repetitive inspections (measurements)
of the angular clearances of the TGB, and, depending on the findings,
additional repetitive inspections (measurements) of the angular
clearances of the TGB at a reduced interval and replacement of the TGB
with a serviceable TGB. EASA AD 2021-0184R1 provides terminating action
for the repetitive inspections at the reduced interval for a helicopter
if, during two consecutive inspections, the value of the measured
angular clearance remains unchanged for that 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 helicopters have been approved by EASA and are approved for
operation in the United States. Pursuant to the FAA's bilateral
agreement with the European Union, EASA has notified the FAA about the
unsafe condition described in its AD. 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 helicopters of the same type design.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in EASA AD 2021-0184R1, described previously, as incorporated by
reference, except for any differences identified as exceptions in the
regulatory text of this proposed AD.

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 2021-0184R1 by reference in the FAA
final rule. This proposed AD would, therefore, require compliance with
EASA AD 2021-0184R1 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 2021-0184R1 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 2021-
0184R1. Service information referenced in EASA AD 2021-0184R1 for
compliance will be available at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-1018 after the FAA final
rule is published.

Interim Action

The FAA considers this proposed AD would be 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 38 helicopters of U.S. Registry. The FAA estimates the following
costs to comply with this proposed AD:

Estimated Costs for Required Actions

The FAA estimates the following costs to do any necessary on-
condition action that would be required based on the results of any
required actions. The FAA has no way of determining the number of
helicopters that might need this on-condition action:

Estimated Costs of On-Condition Actions

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: