[Federal Register Volume 90, Number 160 (Thursday, August 21, 2025)]
[Proposed Rules]
[Pages 40786-40789]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-16012]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-1735; Project Identifier MCAI-2024-00408-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 supersede Airworthiness Directive (AD)
2021-20-16, which applies to all Airbus Helicopters Model AS355E, AS
355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters and certain
Model AS 350B3 helicopters. AD 2021-20-16 requires repetitive cleaning
and visual and detailed inspections of the right-hand side of the
vertical fin spar and vertical fin upper attachments for discrepancies
(cracking) with corrective action, if necessary. Since the FAA issued
AD 2021-20-16, Airbus Helicopters developed a modification of the upper
fin assembly. This proposed AD would require the same actions as AD
2021-20-16 and would also require replacement of the upper fin assembly
with a modified upper fin assembly, which would constitute terminating
action for the repetitive inspections. The FAA is proposing this AD to
address the unsafe condition on these products.
DATES: The FAA must receive comments on this NPRM by October 6, 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.
[[Page 40787]]
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-2025-1735; 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 European Union Aviation Agency (EASA) material
identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668
Cologne, Germany; phone: +49 221 8999 000; email: [email protected];
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 Parkway, Room 6N-
321, Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110. It is also available at
regulations.gov under Docket No. FAA-2025-1735.
FOR FURTHER INFORMATION CONTACT: Steven Warwick, Aviation Safety
Engineer, FAA, 1600 Stewart Ave., Suite 410, Westbury, NY 11590; phone:
(817) 222-5225; email: [email protected].
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-2025-1735;
Project Identifier MCAI-2024-00408-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 the 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
Steven Warwick, Aviation Safety Engineer, FAA, 1600 Stewart Ave., 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
The FAA issued AD 2021-20-16, Amendment 39-21754 (86 FR 57550,
dated October 18, 2021) (AD 2021-20-16), for Airbus Helicopters Model
AS355E, AS 355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters,
all serial numbers, and Model AS 350B3 helicopters, all serial numbers
except those that have Airbus Helicopters Modification 073148 in
production. AD 2021-20-16 was prompted by MCAI originated by EASA,
which is the Technical Agent for the Member States of the European
Union. EASA issued EASA AD 2021-0099, dated April 9, 2021 (EASA AD
2021-0099), to correct an unsafe condition identified as cracking in
the spar of the upper part of the vertical fin and fractures in the
front attachment screws.
AD 2021-20-16 requires repetitive cleaning and detailed inspections
for cracking of the vertical fin spar and vertical fin upper
attachments, and corrective action if necessary. The FAA issued this AD
to address cracking in the spar of the upper part of the vertical fin
and fractures in the front attachment screws. This condition could lead
to in-flight separation of the upper part of the vertical fin,
resulting in loss of control of the helicopter.
Actions Since AD 2021-20-16 Was Issued
Since the FAA issued AD 2021-20-16, EASA superseded EASA AD 2021-
0099 through a series of ADs, the most recent being EASA AD 2024-0139,
dated July 12, 2024 (EASA AD 2024-0139) (also referred to as ``the
MCAI''). EASA AD 2024-0139 states that after a further occurrence of a
crack on a Model AS355NP helicopter, EASA concluded there was a need to
temporarily reduce the never-exceed-speed (VNE) for all
AS355 helicopters. In addition, Airbus Helicopters developed a
reinforced upper fin assembly and published service information that
provides instructions for this modification. EASA AD 2024-0139 retains
the repetitive inspections and VNE limitations in its
previous ADs and also requires modification of the helicopter with the
reinforced upper fin assembly, which is terminating action for
inspections and limitations.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2025-1735.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed EASA AD 2024-0139, which specifies procedures for
amending the rotorcraft flight manual (RFM) and installing a placard to
add a speed limitation. EASA AD 2024-0139 allows exceeding the speed
limitation on certain maintenance flights and specifies accomplishing
an inspection after each flight where the speed is exceeded. EASA AD
2024-0139 also requires repetitively inspecting the right-hand external
side around the two top screws of certain upper fin spars for a crack.
EASA AD 2024-0139 specifies that installing an upper fin assembly P/N
355A14-0522-1751 constitutes terminating action for the repetitive
inspection requirements and the speed limitations. Lastly, EASA AD
2024-0139 prohibits installing affected upper fin assemblies 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.
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
[[Page 40788]]
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 2024-0139, described previously, as incorporated by
reference, except for any differences identified as exceptions in the
regulatory text of this proposed AD. See ``Differences Between this
Proposed AD and the MCAI'' for a general discussion of these
differences.
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 2024-0139 by reference in the FAA
final rule. This proposed AD would, therefore, require compliance with
EASA AD 2024-0139 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 2024-0139 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-
0139. Material referenced in EASA AD 2024-0139 for compliance will be
available at www.regulations.gov by searching for and locating Docket
No. FAA-2025-1735 after the FAA final rule is published.
Differences Between This Proposed AD and the MCAI
While the service material referenced in EASA AD 2024-0139 requires
accomplishing dye penetrant inspections, this proposed AD would require
a dye penetrant inspection (DPI) if the affected part has previously
been inspected by a DPI method; otherwise, this proposed AD would
require a fluorescent penetrant inspection (FPI).
Where EASA AD 2024-0139 and the service material referenced in EASA
AD 2024-0139 specify contacting Airbus Helicopters for repair
instructions, this proposed AD would require using a method approved by
the FAA, EASA, or Airbus Helicopters' EASA Design Organization
Approval.
EASA AD 2024-0139 requires informing all flight crew and operating
the helicopter accordingly, whereas this proposed AD would not because
those actions are already required by FAA regulations.
EASA AD 2024-0139 allows a pilot to perform some actions, and this
proposed AD would not.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 650 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.
Amending the RFM and installing a placard to incorporate a speed
limitation would take approximately 1 work-hour and parts would cost
$25 for an estimated cost of $110 per helicopter and $71,500 for the
U.S. fleet.
Cleaning and inspecting the vertical fin spar would take 2.5 work-
hours for an estimated cost of $213 per helicopter and $138,450 for the
U.S. fleet, per inspection cycle.
Modifying the upper fin spar would take 19 work-hours and parts
would cost $25,360 for an estimated cost of $26,975 per helicopter and
$17,533,750 for the U.S. fleet.
If required, performing a DPI or FPI on the upper fin spar would
take 1 work-hour for an estimated cost of $85 per helicopter.
The extent of damage found during the required inspection of the
vertical fin spar could vary significantly from helicopter to
helicopter. The agency has no way of determining how much damage may be
found during these inspections, the cost to repair damaged parts of
each helicopter, or the number of helicopters that might need these
repairs.
The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected operators.
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 that the 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:
0
a. Removing Airworthiness Directive 2021-20-16, Amendment 39-21754 (86
FR 57550, dated October 18, 2021); and
0
b. Adding the following new airworthiness directive:
[[Page 40789]]
Airbus Helicopters: Docket No. FAA-2025-1735; Project Identifier
MCAI-2024-00408-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by October 6, 2025.
(b) Affected ADs
This AD replaces AD 2021-20-16, Amendment 39-21754 (86 FR 57550,
dated October 18, 2021).
(c) Applicability
This AD applies to Airbus Helicopters Model AS 350B3, AS355E, AS
355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters,
certificated in any category, as identified in European Union
Aviation Safety Agency AD 2024-0139, dated July 12, 2024 (EASA AD
2024-0139).
(d) Subject
Joint Aircraft System Component (JASC) Code 5531, Vertical
Stabilizer, Spar/Rib Structure.
(e) Unsafe Condition
This AD was prompted by a report of a structural crack in the
vertical attachment spar of the upper tail fin and fractures in its
two front attachment screws. The FAA is issuing this AD to address
cracking in the upper fin spar and fracturing of the front
attachment screws. The unsafe condition, if not addressed, could
result in in-flight separation of the upper part of the vertical fin
and subsequent loss of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Requirements
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, EASA AD 2024-0139.
(h) Exceptions to EASA AD 2024-0139
(1) Where EASA AD 2024-0139 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(2) Where EASA AD 2024-0139 refers to its effective date or to
any of the dates listed in paragraphs (h)(2)(i) through (iv) of this
AD, this AD requires using the effective date of this AD.
(i) July 12, 2017 (the effective date of EASA AD 2017-0114,
dated June 28, 2017).
(ii) April 23, 2021 (the effective date of EASA AD 2021-0099,
dated April 9, 2021).
(iii) April 14, 2023 (the effective date of EASA AD 2023-0075,
dated April 7, 2023).
(iv) May 18, 2023 (the effective date of EASA AD 2023-0089,
dated May 4, 2023).
(3) Where paragraph (1) of EASA AD 2024-0139 specifies to inform
all flight crew and operate the helicopter accordingly, this AD does
not require those actions.
(4) Although the service material referenced in EASA AD 2024-
0139 allows some actions to be performed by a pilot, this AD does
not.
(5) Where the service material referenced in EASA AD 2024-0139
states ``if you are not sure'', this AD requires replacing that text
with ``to confirm suspected cracks (scratch, line, misalignment,
etc.)''.
(6) Where the service material referenced in EASA AD 2024-0139
states to do a dye-penetrant inspection (DPI), this AD requires the
actions in paragraph (h)(6)(i), (ii), or (iii) of this AD, as
applicable:
(i) If the right-hand (RH) side of the spar (a) has previously
been inspected by a DPI method, accomplish a DPI of the RH side of
the spar (a).
(ii) If the RH side of the spar (a) has not previously been
inspected by a DPI, accomplish a fluorescent penetrant inspection
(FPI) of the RH-hand side of the spar (a), instead of a DPI.
(iii) If you cannot determine whether the RH side of the spar
(a) has previously been inspected by a DPI, clean all surfaces to be
inspected and accomplish an FPI of the RH side of the spar (a)
instead of a DPI.
Note 1 to paragraph (h)(6)(iii): Work Card 20-02-09-101 (MTC)
contains DPI information related to this AD.
Note 2 to paragraph (h)(6)(iii): When entering compliance with
the applicable paragraph of the AD into the helicopter maintenance
records, explicitly documenting that a dye penetrant inspection was
performed improves the accuracy of maintenance records regarding use
of dye penetrant inspection dye.
(7) Where the service material referenced in EASA AD 2024-0139
refers to damage, for this AD, damage is defined as looseness,
corrosion, broken or missing lockwire, loss of protective surface
finish, deformation, fracture, crack, or nick.
(8) Where paragraph (8) of EASA AD 2024-0139 states
``maintenance flight'', this AD requires replacing that text with
``flight to perform an operational check as specified in 14 CFR
91.407''.
(9) Where paragraph (10) of EASA AD 2024-0139 and the service
material referenced in EASA AD 2024-0139 specify contacting Airbus
Helicopters for repair instructions, this AD requires using a repair
method approved by the FAA, EASA, or Airbus Helicopters' EASA Design
Organization Approval (DOA). If approved by the DOA, the approval
must include the DOA-authorized signature.
(10) Where the service material referenced in EASA AD 2024-0139
specifies to discard parts, this AD requires removing these parts
from service.
(11) Where paragraph (16) of EASA AD 2024-00139 only allows
credit for the initial actions in paragraphs (4) through (9) of EASA
AD 2024-00139, this AD allows credit for any action in paragraphs
(4) through (9) of EASA AD 2024-00139.
(12) This AD does not adopt the ``Remarks'' section of EASA AD
2024-0139.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2024-0139 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 local Flight
Standards District 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: [email protected].
(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 Steven Warwick,
Aviation Safety Engineer, FAA, 1600 Stewart Ave., Suite 410,
Westbury, NY 11590; phone: (817) 222-5225; email:
[email protected].
(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 2024-0139,
dated July 12, 2024.
(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: [email protected]; website: easa.europa.eu. You may
find the EASA material on the EASA website at ad.easa.europa.eu.
(4) 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.
(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 www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].
Issued on August 18, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-16012 Filed 8-20-25; 8:45 am]
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