Proposed Rule2025-23258
Airworthiness Directives; Airbus Helicopters Deutschland GmbH (AHD) Helicopters
Primary source
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Published
December 18, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters. This proposed AD was prompted by a report of a main rotor head (MRH) having the same part number (P/N) and serial number (S/N) as another MRH due to incorrect modification instructions where the modified part serial number was not re-identified and the MRH can be operated with the wrong associated log card if accidently interchanged. This proposed AD would require performing a one-time consistency check of the P/N and S/N of the MRH, performing corrective actions if applicable, determining if the MRH has been modified, and re-identifying the modified MRH. The proposed AD would also allow replacing the MRH as an optional action and would prohibit the installation of an affected MRH on any helicopter. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 90 Issue 241 (Thursday, December 18, 2025)</title>
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[Federal Register Volume 90, Number 241 (Thursday, December 18, 2025)]
[Proposed Rules]
[Pages 59078-59081]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-23258]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-5393; Project Identifier MCAI-2025-00157-R]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters Deutschland GmbH
(AHD) 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 Deutschland GmbH (AHD) Model MBB-BK 117 A-1,
MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, and
MBB-BK 117 C-1 helicopters. This proposed AD was prompted by a report
of a main rotor head (MRH) having the same part number (P/N) and serial
number (S/N) as another MRH due to incorrect modification instructions
where the modified part serial number was not re-identified and the MRH
can be operated with the wrong associated log card if accidently
interchanged. This proposed AD would require performing a one-time
consistency check of the P/N and S/N of the MRH, performing corrective
actions if applicable, determining if the MRH has been modified, and
re-identifying the modified MRH. The proposed AD would also allow
replacing the MRH as an optional action and would prohibit the
installation of an affected MRH on any helicopter. The FAA is proposing
this AD to address the unsafe condition on these products.
DATES: The FAA must receive comments on this NPRM by February 2, 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-2025-5393; 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#95d4d1e6d5f0f4e6f4bbf0e0e7fae5f4bbf0e0"><span class="__cf_email__" data-cfemail="7c3d380f3c191d0f1d5219090e130c1d521909">[email protected]</span></a>; website: easa.europa.eu. You may find this material
on the EASA website at ad.easa.europa.eu.
<bullet> 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
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2025-5393.
FOR FURTHER INFORMATION CONTACT: Promita Dey, Aviation Safety Engineer,
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (316)
946-4106; email: <a href="/cdn-cgi/l/email-protection#c5b5b7aaa8acb1a4eba1a0bc85a3a4a4eba2aab3"><span class="__cf_email__" data-cfemail="5525273a383c21347b31302c153334347b323a23">[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-2025-5393; Project Identifier
MCAI-2025-00157-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
[[Page 59079]]
(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 Promita Dey, 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, issued EASA AD 2025-0028, dated February 7, 2025 (EASA
AD 2025-0028) (also referred to as the MCAI), to correct an unsafe
condition on Airbus Helicopters Deutschland GmbH Model MBB-BK117 A-1,
MBB-BK117 A-3, MBB-BK117 A-4, MBB-BK117 B-1, MBB-BK117 B-2, and MBB-
BK117 C-1 helicopters. The MCAI states that an occurrence was reported
of two MRHs having an identical P/N and S/N. The MCAI further states
that a subsequent investigation determined that the duplicate
identification was due to incorrect modification instructions for the
MRH in an Airbus Helicopters service information notice where the
modified part serial number was not re-identified; this could result in
the MRH being operated with the wrong associated log card if
incorrectly interchanged. This condition, if not detected and
corrected, could result in operation of an MRH and its critical parts
beyond certified limits and lead to failure of certain parts and
consequent 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-2025-5393.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed EASA AD 2025-0028, which specifies procedures for
a one-time consistency check of the P/N and S/N of the MRH to verify
against the existing helicopter log card or equivalent record and,
depending on the results, contacting Airbus Helicopters for approved
instructions. EASA AD 2025-0028 also specifies procedures for
performing an additional check of the existing helicopter log card or
equivalent record to determine if the MRH has been modified and
procedures for re-identifying an MRH that has been modified. EASA AD
2025-0028 allows replacing the MRH with a serviceable part in
accordance with the instructions of the applicable Aircraft Maintenance
Manual as an optional action to accomplishing the initial consistency
check and the corrective actions. EASA AD 2025-0028 prohibits
installing an affected MRH 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 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, it 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 2025-0028, 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.
Differences Between This Proposed AD and the MCAI
Where the MCAI specifies 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.
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 2025-0028 by reference in the FAA final rule. This proposed AD
would, therefore, require compliance with EASA AD 2025-0028 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 2025-0028 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 2025-0028. Material required by
EASA AD 2025-0028 for compliance will be available at <a href="http://regulations.gov">regulations.gov</a>
under Docket No. FAA-2025-5393 after the FAA final rule is published.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 34 helicopters of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD.
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Perform consistency check............. 2 work-hours x $85 per $0 $170 $5,780
hour = $170.
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The FAA estimates the following costs to do any actions that would
be required based on the results of the proposed inspection. The agency
has no way of determining the number of helicopters that might need
these actions.
[[Page 59080]]
On-Condition Costs
----------------------------------------------------------------------------------------------------------------
Cost per
Action Labor cost Parts cost product
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Review existing helicopter log card or 1 work-hour x $85 per hour = $85 $0 $85
equivalent record.
Re-identify MRH............................... 1 work-hour x $85 per hour = $85 0 85
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The FAA has received no definitive data on which to base the cost
estimates for the corrective actions specified in this proposed AD.
Optional Action Costs
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Replace MRH...................... 10 work-hours x $85 Up to $89,000.............. Up to $89,850.
per hour = $850.
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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 Deutschland GmbH (AHD): Docket No. FAA-2025-5393;
Project Identifier MCAI-2025-00157-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by February 2, 2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to Airbus Helicopters Deutschland GmbH (AHD)
Model MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-
1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters, certificated in
any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 6220, Main Rotor
Head.
(e) Unsafe Condition
This AD was prompted by a report of a main rotor head (MRH)
having the same part number (P/N) and serial number (S/N) as another
MRH due to incorrect modification instructions where the modified
part S/N was not re-identified and the MRH can be operated with the
wrong associated log card if accidently interchanged. The FAA is
issuing this AD to detect and correct the incorrect identification
of S/Ns and P/Ns on MRHs which, if not addressed, could result in
operation of an MRH and its critical parts beyond certified limits
and lead to failure of certain parts and consequent 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, European Union Aviation Safety Agency (EASA) AD
2025-0028, dated February 7, 2025 (EASA AD 2025-0028).
(h) Exceptions to EASA AD 2025-0028
(1) Where EASA AD 2025-0028 refers to its effective date, this
AD requires using the effective date of this AD.
(2) Where EASA AD 2025-0028 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(3) Where paragraphs (2) and (4) of EASA AD 2025-0028 specify
discrepancy, for the purposes of this AD, a discrepancy can be
defined as the serial number on the MRH [Main Rotor Head] not
matching the serial number on the helicopters existing log card or
equivalent record.
(4) Where the material referenced in EASA AD 2025-0028 specifies
``check'', this AD requires replacing that text with ``inspect''.
(5) Where EASA AD 2025-0028 and the material referenced in EASA
AD 2025-0028 specifies ``MRH log card'', this AD requires replacing
that text with ``existing helicopter log card or equivalent
record''.
(6) Where EASA AD 2025-0028 or the referenced material specifies
to contact AH [Airbus Helicopters] to obtain approved instructions,
or specifies a part is eligible for installation in accordance with
AH instructions, this AD requires those actions done in accordance
with a method approved
[[Page 59081]]
by the Manager, International Validation Branch, FAA; or EASA; or
Airbus Helicopters' EASA Design Organization Approval (DOA). If
approved by the DOA, the approval must include the DOA-authorized
signature.
(7) This AD does not adopt the ``Remarks'' section of EASA AD
2025-0028.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2025-0028 specifies
to submit certain information to the manufacturer, this AD does not
require that action.
(j) Alternative Methods of Compliance (AMOCs)
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#61202c2e22210700004f060e17"><span class="__cf_email__" data-cfemail="fabbb7b5b9ba9c9b9bd49d958c">[email protected]</span></a>. Before using any approved AMOC, notify your
appropriate principal inspector, or lacking a principal inspector,
the manager of the responsible Flight Standards Office.
(k) Additional Information
For more information about this AD, contact Promita Dey,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (913) 563-8269; email:
<a href="/cdn-cgi/l/email-protection#fd8d8f929094899cd3999884bd9b9c9cd39a928b"><span class="__cf_email__" data-cfemail="3f4f4d5052564b5e115b5a467f595e5e11585049">[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 2025-0028,
dated February 7, 2025.
(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#94d5d0e7d4f1f5e7f5baf1e1e6fbe4f5baf1e1"><span class="__cf_email__" data-cfemail="fcbdb88fbc999d8f9dd299898e938c9dd29989">[email protected]</span></a>; website: easa.europa.eu. You may
find this 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 Parkway, 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 <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#8ee8fca0e7e0fdfeebedfae7e1e0cee0effcefa0e9e1f8"><span class="__cf_email__" data-cfemail="7513075b1c1b06051016011c1a1b351b1407145b121a03">[email protected]</span></a>.
Issued on December 15, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-23258 Filed 12-17-25; 8:45 am]
BILLING CODE 4910-13-P
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