DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2147; Project Identifier MCAI-2022-01515-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 EC 155B, EC155B1, SA-365N, SA-365N1,
AS-365N2, and AS 365 N3 helicopters. This proposed AD was prompted by
an engine compartment fire where the upper stiffener of the central
firewall in the engine compartment was found damaged. This proposed AD
would require replacing the aluminum central firewall stiffener with a
titanium central firewall stiffener and prohibit installing an aluminum
central firewall stiffener. 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 November 14, 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-2024-2147; 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 this 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-2024-2147.

Other Related Material: For Airbus Helicopters 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: Hye Yoon Jang, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (206) 231-3758; email: Hye.Yoon.Jang@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-2024-2147; Project Identifier
MCAI-2022-01515-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 Hye
Yoon Jang, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite
410, Westbury, NY 11590; phone: (206) 231-3758; email:
Hye.Yoon.Jang@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 European Union Aviation Safety Agency AD
2022-0231, dated November 28, 2022 (EASA AD 2022-0231), to correct an
unsafe condition on Airbus Helicopters Model EC 155B, EC155B1, SA-365N,
SA-365N1, AS-365N2, and AS 365 N3 helicopters.

This proposed AD was prompted by an engine fire where the upper
stiffener of the central firewall, made of aluminum, in the engine
compartment was found damaged. The FAA is proposing this AD to address
failure of a central firewall stiffener made of aluminum, possibly due to its
inability to withstand high temperatures of an engine fire and
subsequently not seal the engine compartment properly. In the event of
an engine fire, the unsafe condition, if not addressed, could result in
fire propagating from one engine compartment to the other and
subsequent loss of control of the helicopter. See EASA AD 2022-0231 for
additional background information.

You may examine EASA AD 2022-0231 in the AD docket at
regulations.gov under Docket No. FAA-2024-2147.

Related Material Under 1 CFR Part 51

The FAA reviewed EASA AD 2022-0231 which requires replacing
aluminum central firewall stiffeners with titanium central firewall
stiffeners and prohibits installing an aluminum central firewall
stiffener 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.

Other Related Material

The FAA reviewed Airbus Helicopters Alert Service Bulletin (ASB)
No. AS365-71.00.28 and ASB No. EC155-71A015, each Revision 0 and dated
October 25, 2022. This material specifies procedures for replacing the
aluminum stiffener on the center firewall with a titanium stiffener.

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 EASA AD 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 these same type designs.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in EASA AD 2022-0231, 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 2022-0231 by reference in the FAA
final rule. This proposed AD would, therefore, require compliance with
EASA AD 2022-0231 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 2022-0231 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 2022-
0231. Material referenced in EASA AD 2022-0231 for compliance will be
available at regulations.gov under Docket No. FAA-2024-2147 after the
FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 35 helicopters of U.S. Registry. Labor rates are estimated at
$85 per work-hour. Based on these numbers, the FAA estimates that
operators may incur the following costs in order to comply with this
proposed AD.

Replacing the aluminum central firewall stiffener with a titanium
central firewall stiffener would take 7 work-hours and parts would cost
$1,737 to $2,801 depending on part number for an estimated cost of
$2,332 to $3,396 per helicopter and up to $81,620 to $118,860 for the
U.S. fleet.

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: