DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2419; Project Identifier MCAI-2023-00366-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 (Airbus) Model AS350B, AS350B1, AS350B2,
AS350B3, AS350BA, AS350D, AS355E, AS355F, AS355F1, AS355F2, AS355N,
AS355NP, EC130B4, and EC130T2 helicopters. This proposed AD was
prompted by a manufacturer assessment that determined additional
actions are necessary to improve particle detection for main gearboxes
(MGBs) with certain planet gear bearings installed. This proposed AD
would require repetitively inspecting the MGB bevel wheel for the
presence of particles, repetitively inspecting the MGB magnetic plug
for particles, and prohibit installing an affected MGB unless certain
requirements are met. 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 December 20, 2024.

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-2024-2419; 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.

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 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 Pkwy., Room 6N-321,
Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110. The EASA material is also
available at regulations.gov under Docket No. FAA-2024-2419.

Other Related Material: For Airbus material identified in this
proposed AD, contact Airbus Helicopters, 2701 North Forum Drive, Grand
Prairie, TX 75052; phone: (972) 641-0000 or (800) 232-0323; fax: (972)
641-3775; or at airbus.com/en/products-services/helicopters/hcare-services/airbusworld.

FOR FURTHER INFORMATION CONTACT: Dan McCully, Aviation Safety Engineer,
FAA, 1600 Stewart Ave., Suite 410, Westbury, NY 11590; phone: (404)
474-5548; email: william.mccully@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-2024-2419; Project Identifier
MCAI-2023-00366-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 Dan
McCully, Aviation Safety Engineer, FAA, 1600 Stewart Ave., Suite 410,
Westbury, NY 11590; phone: (404) 474-5548; email:
william.mccully@faa.gov. 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 2023-0044, dated February 28, 2023,
(EASA AD 2023-0044) to correct an unsafe condition on Airbus Model AS
350 B, AS 350 D, AS 350 B1, AS 350 B2, AS 350 BA, AS 350 BB, AS 350 B3,
EC 130 B4, EC 130 T2, AS 355 E, AS 355 F, AS 355 F1, AS 355 F2, AS355
N, and AS355 NP helicopters. EASA advises that after a fleet design
review for detection of particles in the MGB, it was determined that
additional maintenance actions are necessary to improve detection of
particles in the MGB. The FAA is proposing this AD to detect and
correct the presence of particles in the MGB, which if not addressed,
could result in reduced or loss of control of the helicopter.

You may examine EASA AD 2023-0044 in the AD docket at
regulations.gov under Docket No. FAA-2024-2419.

Material Incorporated by Reference Under 1 CFR Part 51

EASA AD 2023-0044 requires repetitive borescope visual inspections
of the bevel wheel of the affected MGB for particles, collecting and
analyzing any found particles, and depending on the results, further
actions, accomplishing corrective action in accordance with the ASB
defined within, or contacting AH [Airbus Helicopters] for further
corrective action. EASA AD 2023-0044 also requires accomplishing a
borescope visual inspection of the bevel wheel of the affected MGB for
particles following the detection of any particles at the MGB magnetic
plug during accomplishment of certain maintenance tasks and depending
on the results, taking corrective action. Lastly, EASA AD 2023-0044
prohibits installing an affected MGB on any helicopter unless it is a
serviceable part as defined within and certain requirements are met.

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.

Other Related Material

The FAA reviewed Airbus Alert Service Bulletin No. AS350-05.01.04,
No. AS355-05.00.87, and No. EC130-05A040, each Revision 0, and each
dated January 25, 2023. This material specifies procedures for
borescope inspecting the MGB bevel wheel for particles and, depending
on the results, replacing a damaged epicyclic module or bevel reduction
module with an airworthy part, and collecting the particles using a
vacuum pump and analyzing the particles.

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 these same type designs.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in EASA AD 2023-0044, 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 EASA AD 2023-0044."

This proposed AD would require certain actions within compliance
times specified in certain material referenced for compliance in EASA
AD 2023-0044, particularly for corrective actions for scales, flakes,
or splinters. Depending on the measurements of the scales, flakes, or
splinters, corrective actions include close monitoring, metallurgical
analysis within 50 hours time-in-serivce, or removing each affected
module and additional actions when certain criteria are exceeded.

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 2023-0044 by reference in the FAA
final rule. This proposed AD would, therefore, require compliance with
EASA AD 2023-0044 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 2023-0044 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-
0044. Material referenced in EASA AD 2023-0044 for compliance will be
available at www.regulations.gov by searching for and locating Docket
No. FAA-2024-2419 after the FAA final rule is published.

Differences Between This Proposed AD and EASA AD 2023-0044

EASA AD 2023-0044 applies to Model AS350BB helicopters, whereas
this proposed AD would not because that model is not FAA-type certificated.

Where Note 1 in the material referenced in EASA AD 2023-0044
specifies the option of 1 mechanical technician and 1 crew member, for
this proposed AD, the pilot is only permitted to turn the tail rotor
(b) because the other actions specified in the note must be
accomplished by persons authorized under 14 CFR 43.3. Therefore, for
the purposes of this proposed AD, the owner/operator (pilot) may turn
the tail rotor (b) and must enter compliance with the applicable
paragraph of this proposed AD in the helicopter maintenance records in
accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The pilot may
perform this action because it only involves turning the tail rotor
(b). This action can be performed equally well by a pilot or a
mechanic. This action is an exception to the FAA's standard maintenance
regulations.

This proposed AD would not require complying with paragraph (2) of
EASA AD 2023-0044. Instead, this proposed AD would require repetitively
inspecting the MGB magnetic plug for particles and, if there is any
particle, accomplishing a borescope visual inspection, as specified in
paragraphs (h)(6)(i) and (ii) of this proposed AD.

Where the material referenced in EASA AD 2023-0044 specifies
contacting Airbus Helicopters for a certain action, this proposed AD
would require accomplishing action in accordance with a method approved
the FAA, EASA, or Airbus Helicopters' EASA Design Organization
Approval.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 522 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.

A repetitive visual borescope inspection of the MGB bevel wheel
would take 1 work-hour for an estimated cost of $85 per helicopter and
$44,370 for the U.S. fleet, per inspection cycle.

If necessary, collecting and performing a metallurgical analysis of
the detected particles would take 6 work-hours for an estimated cost of
$510 per helicopter, per analysis.

Repetitively inspecting the magnetic plugs of the MGB would take 1
work-hour for an estimated cost of $85 per helicopter and $44,370 for
the U.S. fleet, per inspection cycle.

If required, close monitoring would take 2 work-hours for an
estimated cost of $170 per helicopter, per close monitoring cycle.

Accomplishing a visual borescope inspection of the MGB bevel wheel
as a result of an MGB magnetic plug inspection would take 1 work-hour
for an estimated cost of $85 per helicopter.

If necessary, replacing an epicyclic module would take 56 work-
hours and parts would cost $50,524 (overhauled) for an estimated cost
of $55,284 per module.

If necessary, replacing a bevel reduction module would take 56
work-hours and parts would cost $18,500 (overhaled) for an estimated
cost of $23,260 per module.

Certain corrective action could vary significantly from helicopter
to helicopter. The FAA has no data to determine the costs to accomplish
the corrective action.

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: