Proposed Rule2026-19729
Airworthiness Directives; Airbus Helicopters
Primary source
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Published
September 28, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Model AS 365 N2, AS 365 N3, EC 155 B, EC 155 B1, SA 365 N, and SA 365 N1 helicopters. This proposed AD was prompted by gaps between the seals and engine cowling, which were found during an investigation related to an engine compartment fire. Gaps between the seals and engine cowling could cause inadequate sealing of the engine compartment firewalls leading to fire propagation between engine compartments and reduced effectiveness of the extinguishing agent. This proposed AD would require modifying the engine compartment firewalls by installing angle-brackets along the firewalls. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 186 (Monday, September 28, 2026)</title>
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[Federal Register Volume 91, Number 186 (Monday, September 28, 2026)]
[Proposed Rules]
[Pages 61164-61166]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-19729]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 91, No. 186 / Monday, September 28, 2026 /
Proposed Rules
[[Page 61164]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-11787; Project Identifier MCAI-2026-00249-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 365 N2, AS 365 N3, EC 155 B, EC 155
B1, SA 365 N, and SA 365 N1 helicopters. This proposed AD was prompted
by gaps between the seals and engine cowling, which were found during
an investigation related to an engine compartment fire. Gaps between
the seals and engine cowling could cause inadequate sealing of the
engine compartment firewalls leading to fire propagation between engine
compartments and reduced effectiveness of the extinguishing agent. This
proposed AD would require modifying the engine compartment firewalls by
installing angle-brackets along the firewalls. 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 12, 2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-11787; 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:
<bullet> For European Union Aviation Safety Agency (EASA) material
identified in this proposed AD, contact EASA, Konrad-Adenauer-Ufer 3,
50668 Cologne, Germany; phone: +49 221 8999 000; email:
<a href="/cdn-cgi/l/email-protection#c58481b685a0a4b6a4eba0b0b7aab5a4eba0b0"><span class="__cf_email__" data-cfemail="2061645360454153410e4555524f50410e4555">[email protected]</span></a>; website: easa.europa.eu. You may find this material
on the EASA website at ad.easa.europa.eu. It is also available at
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2026-11787.
<bullet> You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 10101 Hillwood Parkway,
Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110.
FOR FURTHER INFORMATION CONTACT: Evan Weaver, Aviation Safety Engineer,
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (316)
944-8910; email: <a href="/cdn-cgi/l/email-protection#b5d0c3d4db9bc59bc2d0d4c3d0c7f5d3d4d49bd2dac3"><span class="__cf_email__" data-cfemail="87e2f1e6e9a9f7a9f0e2e6f1e2f5c7e1e6e6a9e0e8f1">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments using a method listed
under ADDRESSES. Include ``Docket No. FAA-2026-11787; Project
Identifier MCAI-2026-00249-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
<a href="http://regulations.gov">regulations.gov</a>, 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 Evan
Weaver, 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 2026-0056, dated March 16, 2026
(EASA AD 2026-0056) (also referred to as the MCAI), to correct an
unsafe condition on all 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 that during an investigation following an engine compartment
fire, gaps were identified between the seals and engine cowlings.
Analysis showed that some seals along the firewalls did not fully
compress against the engine cowlings. Thus, the seal is not fully
completed between the main gear box, the left engine compartment and
the right engine compartment. Without a full seal, the extinguishing
agent is not contained within the compartment when the pilot operates
the engine fire extinguisher.
The FAA is proposing this AD to prevent fire propagation between
engine compartments and the reduced
[[Page 61165]]
effectiveness of the extinguishing agent due to inadequate sealing of
the engine compartment firewalls. The unsafe condition, if not
addressed, could allow fire propagation from one engine compartment to
another and reduce the effectiveness of the extinguishing agent in the
event of an engine fire, which could result in loss of control of the
helicopter.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-11787.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed EASA AD 2026-0056, which specifies procedures for
modifying the engine compartment firewalls by installing angle-brackets
along the firewalls to improve sealing between the seals and engine
cowlings. 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 civil aviation authority
(CAA) 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 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 design.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified
in EASA AD 2026-0056, 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 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 2026-0056 by reference in the FAA final rule. This proposed AD
would, therefore, require compliance with EASA AD 2026-0056 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 2026-0056 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 2026-0056. Material required by
EASA AD 2026-0056 for compliance will be available at <a href="http://regulations.gov">regulations.gov</a>
under Docket No. FAA-2026-11787 after the FAA final rule is published.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 43 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost on U.S.
Action Labor cost Parts cost Cost per product operators
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Modification of engine 6 work-hours x $85 Up to $32,360...... Up to $32,870...... $1,413,410
compartment firewalls. per hour = $510.
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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
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:
Airbus Helicopters: Docket No. FAA-2026-11787; Project Identifier
MCAI-2026-00249-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by November 12, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to all Airbus Helicopters Model AS 365 N2, AS
365 N3, EC 155 B, EC
[[Page 61166]]
155 B1, SA 365 N, and SA 365 N1 helicopters, certificated in any
category.
(d) Subject
Joint Aircraft System Component (JASC) Code 5412, Nacelle/pylon,
bulkhead/firewall.
(e) Unsafe Condition
This AD was prompted by gaps between the seals and engine
cowling, which were found during an investigation related to an
engine compartment fire. The FAA is issuing this AD to prevent fire
propagation between engine compartments and the reduced
effectiveness of the extinguishing agent due to inadequate sealing
of the engine compartment firewalls. The unsafe condition, if not
addressed, could allow fire propagation from one engine compartment
to another and reduce the effectiveness of the extinguishing agent
in the event of an engine fire, which could result in loss of
control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
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 2026-0056,
dated March 16, 2026 (EASA AD 2026-0056).
(h) Exceptions to EASA AD 2026-0056
(1) Where EASA AD 2026-0056 refers to its effective date, this
AD requires using the effective date of this AD.
(2) Where EASA AD 2026-0056 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(3) Where the material referenced in EASA AD 2026-0056 specifies
``check'', this AD requires replacing that text with ``inspect''.
(4) This AD does not adopt the ``Remarks'' section of EASA AD
2026-0056.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2026-0056 specifies
to submit certain information to the manufacturer, this AD does not
require that action.
(j) 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 responsible Flight
Standards 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 (k) of this AD and
email to: <a href="/cdn-cgi/l/email-protection#06474b49454660676728616970"><span class="__cf_email__" data-cfemail="5415191b17143235357a333b22">[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.
(k) Additional Information
For more information about this AD, contact Evan Weaver,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (316) 944-8910; email:
<a href="/cdn-cgi/l/email-protection#aacfdccbc484da84ddcfcbdccfd8eacccbcb84cdc5dc"><span class="__cf_email__" data-cfemail="701506111e5e005e071511061502301611115e171f06">[email protected]</span></a>.
(l) 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 2026-0056,
dated March 16, 2026.
(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#66272215260307150748031314091607480313"><span class="__cf_email__" data-cfemail="ebaaaf98ab8e8a988ac58e9e99849b8ac58e9e">[email protected]</span></a>; website: easa.europa.eu. You may
find this EASA AD on the EASA website at ad.easa.europa.eu.
(4) You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 10101 Hillwood Parkway,
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#5b3d29753235282b3e382f3234351b353a293a753c342d"><span class="__cf_email__" data-cfemail="ed8b9fc384839e9d888e99848283ad838c9f8cc38a829b">[email protected]</span></a>.
Issued on September 23, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-19729 Filed 9-25-26; 8:45 am]
BILLING CODE 4910-13-P
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