Rule2025-20135
Airworthiness Directives; Airbus Helicopters Deutschland GmbH Helicopters
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
November 18, 2025
Effective
December 23, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for all Airbus Helicopters Deutschland GmbH Model MBB-BK 117 D-2 and MBB-BK 117 D-3 helicopters. This AD was prompted by reports of airspeed and altitude indication errors. This AD requires revising the existing rotorcraft flight manual supplement (RFMS) for the helicopter, replacing the air conditioning system (ACS) condenser outlet grids with ACS condenser outlet covers, and prohibiting the installation of ACS condenser outlet grids. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 90 Issue 220 (Tuesday, November 18, 2025)</title>
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[Federal Register Volume 90, Number 220 (Tuesday, November 18, 2025)]
[Rules and Regulations]
[Pages 51504-51506]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-20135]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-1106; Project Identifier MCAI-2023-01052-R;
Amendment 39-23159; AD 2025-20-06]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters Deutschland GmbH
Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Airbus Helicopters Deutschland GmbH Model MBB-BK 117 D-2 and MBB-BK 117
D-3 helicopters. This AD was prompted by reports of airspeed and
altitude indication errors. This AD requires revising the existing
rotorcraft flight manual supplement (RFMS) for the helicopter,
replacing the air conditioning system (ACS) condenser outlet grids with
ACS condenser outlet covers, and prohibiting the installation of ACS
condenser outlet grids. The FAA is issuing this AD to address the
unsafe condition on these products.
DATES: This AD is effective December 23, 2025.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of December 23,
2025.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-1106; 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 final rule, the mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
address for Docket Operations is U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
<bullet> For European Union Aviation Safety Agency (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#95d4d1e6d5f0f4e6f4bbf0e0e7fae5f4bbf0e0"><span class="__cf_email__" data-cfemail="7f3e3b0c3f1a1e0c1e511a0a0d100f1e511a0a">[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
[[Page 51505]]
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-2025-1106.
FOR FURTHER INFORMATION CONTACT: Aryanna Sanchez, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (817) 222-4058; email: <a href="/cdn-cgi/l/email-protection#7f1e0d061e11111e510b510c1e111c171a053f191e1e51181009"><span class="__cf_email__" data-cfemail="1677646f77787877386238657778757e736c5670777738717960">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all Airbus Helicopters
Deutschland GmbH Model MBB-BK 117 D-2 and MBB-BK 117 D-3 helicopters.
The NPRM was published in the Federal Register on June 18, 2025 (90 FR
25911). The NPRM was prompted by AD 2023-0175, dated October 5, 2023,
issued by EASA, which is the Technical Agent for the Member States of
the European Union (EASA AD 2023-0175) (also referred to as the MCAI).
The MCAI states that there have been reports of airspeed and altitude
indication errors. Subsequent investigation revealed that the ACS
condenser outlets are in close proximity to the static ports, and air
from the outlets affects the static ports during flight. The static
ports and pitot tubes measure different pressures, which are then used
to calculate airspeed, altitude, and vertical speed. Incorrect readings
can then occur. This condition, if not corrected, could lead to reduced
situational awareness, possibly resulting in a significant increase in
crew workload.
In the NPRM, the FAA proposed to require revising the existing RFMS
for the helicopter, replacing the ACS condenser outlet grids with ACS
condenser outlet covers, and prohibiting the installation of ACS
condenser outlet grids.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-1106.
Discussion of Final Airworthiness Directive
Comments
The FAA received no comments on the NPRM or on the determination of
the costs.
Additional Changes Made to This AD
In the NPRM, the FAA proposed an exception that would not require a
note from the referenced service material after replacing the left-hand
or right-hand exhaust cowling assembly. However, the FAA has revised
this AD to remove that exception because the note is merely a
recommendation and does not mandate any action. Therefore, after
replacing the left-hand or right-hand exhaust cowling assembly,
operators are still required to perform all actions as specified in the
required material.
Conclusion
These products have been approved by the civil 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, that authority has notified the FAA of the unsafe condition
described in the MCAI referenced above. The FAA reviewed the relevant
data, considered any comments received, and determined that air safety
requires adopting this AD as proposed. Accordingly, the FAA is issuing
this AD to address the unsafe condition on these products. Except for
minor editorial changes, and any other changes described previously,
this AD is adopted as proposed in the NPRM. None of the changes will
increase the economic burden on any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed EASA AD 2023-0175, which specifies procedures for
amending the applicable RFMS by incorporating new altitude corrections
if the helicopter has ACS condenser outlet grids, and not covers,
installed. EASA AD 2023-0175 also specifies procedures for replacing
the ACS condenser outlet grid part number (P/N) D211M1821302 or P/N
D211M1822302 with ACS condenser outlet cover P/N D211M1821402 or P/N
D211M1822402 and prohibits installing ACS condenser outlet grids 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.
Differences Between This AD and the MCAI
The MCAI applies to Model MBB-BK117 D-2m and MBB-BK117 D-3m
helicopters, whereas this AD does not because those models do not have
an FAA type certificate.
The MCAI requires operators to ``inform all flight crews'' of the
revisions to the RFMS, and thereafter to ``operate the helicopter
accordingly.'' However, this AD does not require those actions as those
actions are already required by FAA regulations. FAA regulations
require operators furnish to pilots any changes to the rotorcraft
flight manual (RFM) (for example, 14 CFR 135.21) and that pilots are
familiar with the RFM (for example, 14 CFR 91.505). As with any other
flight crew training requirement, training on the updated RFM content
is tracked by the operators and recorded in each pilot's training
record, which is available for the FAA to review. FAA regulations also
require pilots to follow the procedures in the existing RFM including
all updates. Section 91.9 requires that any person operating a civil
aircraft must comply with the operating limitations specified in the
RFM. Therefore, including a requirement in this AD to operate the
helicopter according to the revised RFM would be redundant and
unnecessary.
The MCAI does not have any flight restrictions, whereas this AD
requires a revision to the RFMS restricting helicopters to operation
under visual flight rules (VFR) until the helicopter is modified with
ACS condenser outlet covers.
The MCAI specifies amending the applicable RFMS, whereas this AD
specifically requires amending the Limitations Section of the
applicable RFMS.
Interim Action
The FAA considers that this AD is an interim action. The
manufacturer is currently developing a modification that will address
the unsafe condition identified in this AD. Once this modification is
developed, approved, and available, the FAA might consider further
rulemaking.
Costs of Compliance
The FAA estimates that this AD affects 71 helicopters of U.S.
registry. Labor costs are estimated at $85 per hour. Based on these
numbers, the FAA estimates the following costs to comply with this AD.
Replacing the ACS condenser outlet grids takes 20 work-hours and
parts cost $970, for an estimated cost of $2,670 per helicopter and
$189,570 for the U.S. fleet. Revising the existing RFM for the
helicopter takes 1 work-hour for an estimated cost of $85 per
helicopter and $6,035 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
[[Page 51506]]
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
This AD will not have federalism implications under Executive Order
13132. This AD will 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will 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 Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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:
2025-20-06 Airbus Helicopters Deutschland GmbH: Amendment 39-23159;
Docket No. FAA-2025-1106; Project Identifier MCAI-2023-01052-R.
(a) Effective Date
This airworthiness directive (AD) is effective December 23,
2025.
(b) Affected ADs
None.
(c) Applicability
This AD applies to Airbus Helicopters Deutschland GmbH Model
MBB-BK 117 D-2 and MBB-BK 117 D-3 helicopters, certificated in any
category.
(d) Subject
Joint Aircraft System Component (JASC) Code 2100, Air
Conditioning System.
(e) Unsafe Condition
This AD was prompted by reports of airspeed and altitude
indication errors. The FAA is issuing this AD to address airspeed
and altitude indication errors. The unsafe condition, if not
addressed, could lead to reduced situational awareness, possibly
resulting in a significant increase in crew workload.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Requirements
(1) 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
2023-0175, dated October 5, 2023 (EASA AD 2023-0175).
(2) The owner/operator (pilot) holding at least a private pilot
certificate may revise the existing Rotorcraft Flight Manual for the
helicopter and must enter compliance with this requirement into the
helicopter maintenance records in accordance with 14 CFR 43.9(a) and
14 CFR 91.417(a)(2)(v). The record must be maintained as required by
14 CFR 91.417, 121.380, or 135.439.
(h) Exceptions to EASA AD 2023-0175
(1) Where EASA AD 2023-0175 refers to its effective date, this
AD requires using the effective date of this AD.
(2) Where EASA AD 2023-0175 requires compliance in terms of
flight hours, this AD requires using hours time-in-service.
(3) Where paragraph (1) of EASA AD 2023-0175 states ``by
incorporating the air conditioning system (ACS) rotorcraft flight
manual supplement (RFMS) altitude correction procedure, as defined
in appendix 1 of this AD'', this AD requires replacing that text
with ``by incorporating the ACS RFMS altitude correction procedure,
as defined in appendix 1 of this AD, into the Limitations section
and by adding a visual flight rules (VFR) only restriction to the
procedure''.
(4) Where paragraph (1) of EASA AD 2023-0175 specifies to inform
all flight crews, and operate the helicopter accordingly, this AD
does not require those actions as those actions are already required
by existing FAA operating regulations (see 14 CFR 91.505 and 14 CFR
135.21).
(5) Where paragraph (2) of EASA AD 2023-0175 states ``which
includes the same content as the ACS RFMS altitude correction
procedure'', this AD requires replacing that text with ``which
includes information identical to the information in the ACS RFMS
altitude correction procedure, as defined in appendix 1 of this
AD''.
(6) This AD does not adopt the ``Remarks'' section of EASA AD
2023-0175.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2023-0175 specifies
to submit certain information to the manufacturer, this AD does not
include that requirement.
(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: <a href="/cdn-cgi/l/email-protection#3b7a7674787b5d5a5a155c544d"><span class="__cf_email__" data-cfemail="2465696b67644245450a434b52">[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 Aryanna Sanchez,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone (817) 222-4058; email:
<a href="/cdn-cgi/l/email-protection#30514249515e5e511e441e43515e5358554a705651511e575f46"><span class="__cf_email__" data-cfemail="7514070c141b1b145b015b06141b161d100f351314145b121a03">[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 2023-0175,
dated October 5, 2023.
(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#b0f1f4c3f0d5d1c3d19ed5c5c2dfc0d19ed5c5"><span class="__cf_email__" data-cfemail="d59491a695b0b4a6b4fbb0a0a7baa5b4fbb0a0">[email protected]</span></a>; website: easa.europa.eu. You may
find this 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 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#93f5e1bdfafde0e3f6f0e7fafcfdd3fdf2e1f2bdf4fce5"><span class="__cf_email__" data-cfemail="7e180c5017100d0e1b1d0a1711103e101f0c1f50191108">[email protected]</span></a>.
Issued on November 14, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division,Aircraft
Certification Service.
[FR Doc. 2025-20135 Filed 11-17-25; 8:45 am]
BILLING CODE 4910-13-P
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