[Federal Register Volume 90, Number 68 (Thursday, April 10, 2025)]
[Rules and Regulations]
[Pages 15304-15306]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-06066]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2024-2322; Project Identifier MCAI-2024-00065-Q;
Amendment 39-23002; AD 2025-07-01]
RIN 2120-AA64
Airworthiness Directives; Thommen Aircraft Equipment AG Digital
Air Data Computers
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain THOMMEN AIRCRAFT EQUIPMENT AG (THOMMEN) AC32 Digital Air Data
Computers. This AD results from occurrences of AC32 Digital Air Data
Computers (ADCs) that stop functioning below certain temperatures. This
AD requires replacing an affected AC32 Digital ADC with a serviceable
part. The FAA is issuing this AD to address the unsafe condition on
these products.
DATES: This AD is effective May 15, 2025.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of May 15,
2025.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-2322; 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:
For THOMMEN AIRCRAFT EQUIPMENT material identified in this
AD, contact THOMMEN AIRCRAFT EQUIPMENT AG, Hofackerstrasse 48, 4132
Muttenz, Switzerland; phone: +41 (0) 61 965 22 22; email:
[email protected]; website: thommen.aero.
You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 901 Locust, Kansas City,
MO 64106. 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-2024-2322.
FOR FURTHER INFORMATION CONTACT: William Reisenauer, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (516) 228-7301; email: [email protected].
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 certain THOMMEN AC32
Digital Air Data Computers. The NPRM published in the Federal Register
on September 30, 2024 (89 FR 79480). The NPRM was prompted by AD 2024-
0024, dated January 24, 2024, issued by the European Union Aviation
Safety Agency (EASA), which is the Technical Agent for the Member
States of the European Union (EASA AD 2024-0024) (also referred to as
the MCAI). The MCAI states that there have been occurrences of certain
AC32 Digital ADCs that stopped functioning at temperatures below-20
degrees Celsius. The error is detectable and there is no transmission
of erroneous data. The problem is caused by the power module and the
affected units have been identified. This condition, if not addressed,
could result in insufficient navigational data provided to the flight
crew, resulting in reduced control of the aircraft. The MCAI requires
removing from service each affected part and specifies that only
serviceable parts as defined in the MCAI may be installed.
In the NPRM, the FAA proposed to require replacing an affected AC32
Digital ADC with a serviceable part. The FAA is issuing this AD to
address the unsafe condition on these products.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2024-2322.
Discussion of Final Airworthiness Directive
Comments
The FAA received one comment from an individual commenter and one
comment from Bristow VTOL dba Era Helicopters. The following presents
the comments received on the NPRM and the FAA's response to each
comment.
Request To Revise the Applicability To Include Additional Helicopter
Models
An individual commenter stated that Columbia Helicopters, Inc.
Model 107-II helicopters and Kawasaki Model 107-II helicopters also
have configurations with the subject ADC installed. The FAA infers that
the commenter requested that the applicability of the proposed AD be
revised to include these additional helicopter models.
Bristow VTOL dba Era Helicopters acknowledged that the proposed AD
in paragraph ``(c)(2) Applicability'' mentions that ``Table 1 to
paragraph (c)(2)'' does not limit the models identified in ``Table 1 to
paragraph (c)(2)'' as being the only models that could have an affected
serial number and affected part installed. However, the commenter
stated that, while four Model AW189 helicopters are operating in the
United States, only one helicopter serial number was identified as
having an affected AC32 Digital ADC serial number and part number. The
commenter confirmed that affected AC32 Digital ADC serial numbers and
part numbers are not installed on any Model AW139 helicopter operating
in the United States. Due to this
[[Page 15305]]
information, the commenter requested that the FAA include Model AW189
helicopters in ``Table 1 to paragraph (c)(2).''
Although, as stated in paragraph (c)(2) of the Applicability
section of this AD, the aircraft models specified in Table 1 are not an
exhaustive list of affected models, the FAA agrees with the commenters'
requests. The FAA revised ``Table 1 to paragraph (c)(2)'' of this AD to
include Columbia Helicopters, Inc. Model 107-II helicopters, Kawasaki
Heavy Industries, Limited Model KV107-II helicopters, and Leonardo
S.p.a. Model AW189 helicopters.
Conclusion
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 MCAI referenced above. The FAA reviewed the relevant data,
considered the 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
any changes described previously, this AD is adopted as proposed in the
NPRM. None of the changes increase the economic burden on any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed THOMMEN AIRCRAFT EQUIPMENT Service Bulletin SB
AC32/07, Revision 1.0, dated August 31, 2023 (THOMMEN SB AC32/07,
Revision 1.0). This material specifies procedures for determining if an
aircraft is equipped with an affected AC32 Digital ADC listed in
Appendix A, determining if the actions specified in THOMMEN SB AC32/07,
Revision 1.0, were already accomplished, and replacing any affected
THOMMEN AC32 Digital ADC.
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.
Costs of Compliance
The FAA estimates that this AD affects 401 AC32 Digital ADCs that
are installed on aircraft worldwide. The FAA has no way of determining
how many of these ADCs are installed on aircraft of U.S. registry.
The FAA estimates the following costs to comply with this AD. These
costs assume all 401 AC32 Digital ADCs are installed on aircraft of
U.S. registry. The FAA expects a portion of the affected population to
exist outside of the U.S. and the estimated costs to be lower.
Estimated Costs
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Cost on U.S.
Action Labor cost Parts cost Cost per product operators
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Replace affected AC32 Digital ADC.... 12 work-hours x $85 per $4,477 $5,497 $2,204,297
hour = $1,020.
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The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this 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
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:
2025-07-01 Thommen Aircraft Equipment AG: Amendment 39-23002; Docket
No. FAA-2024-2322; Project Identifier MCAI-2024-00065-Q.
(a) Effective Date
This airworthiness directive (AD) is effective May 15, 2025.
(b) Affected ADs
None.
(c) Applicability
(1) This AD applies to THOMMEN AIRCRAFT EQUIPMENT AG (THOMMEN)
AC32 Digital Air Data Computers (ADCs) having an affected part as
defined in paragraph (f)(1) of this AD.
(2) This appliance is installed on, but not limited to, the
following aircraft models specified in table 1 to paragraph (c)(2)
of this AD, certificated in any category.
[[Page 15306]]
Table 1 to Paragraph (c)(2)--Applicable Aircraft Models
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Type certificate holder Aircraft model
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Airbus Defense and Space S.A. (type CN-235, CN-235-100, CN-235-200,
certificate previously held by and CN-235-300.
Construcciones Aeronauticas, S.A.).
Airbus Helicopters..................... AS332C, AS332C1, AS332L,
AS332L1, AS3323L2.
Airbus Helicopters Deutschland GmbH EC635T2+.
(AHD).
Bell Textron Inc....................... 212, 412, and 412EP.
Bombardier Inc......................... CL-600-1A11 (600).
Columbia Helicopters Inc............... 107-II, 234.
General Atomics Aerotek Systems GmbHl 228-100, 228-101, 228-200, 228-
(type certificate formerly held by 201, 228-202, and 228-212.
DORNIER LUFTFAHRT Inc.).
Gulfstream Aerospace LP................ Westwind Astra 1124 (serial
numbers 004-0410).
International Air Response............. C-130A.
Kawasaki Heavy Industries, Limited..... KV107-II.
Leonardo S.p.a......................... A109, A10A, A109A II, A109C,
A109K2, A109S, 1099SP, AW139,
and AW189.
Textron Aviation Inc................... 200, 300, 500, 501, 550, and
551.
Viking Air Limited..................... CL-215-6B11 (CL-215T Variant).
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(3) This appliance is approved for installation and could be
installed on various aircraft modified by Supplemental Type
Certificate (STC) No. SR09595RC or ST01523WI.
(d) Subject
Joint Aircraft System Component (JASC) Code 3417, Air Data
Computer.
(e) Unsafe Condition
This AD was prompted by occurrences of AC32 Digital ADCs that
stopped functioning due to the power module failing at temperatures
below -20 degrees Celsius. The unsafe condition, if not addressed,
could result in insufficient navigational data provided to the
flight crew, resulting in reduced control of the aircraft.
(f) Definitions
For the purpose of this AD the definitions in paragraphs (f)(1)
through (4) of this AD apply:
(1) Affected part: THOMMEN AC32 Digital ADCs, part numbers (P/N)
AC32.10.21.10.XX, AC32.10.21.11.XX, AC32.11.21.10.XX, and
AC32.11.21.11.XX (where XX represents any alpha/numerical sequence),
and having a serial number (S/N) listed in Appendix A of THOMMEN
AIRCRAFT EQUIPMENT Service Bulletin SB AC32/07, Revision 1.0, dated
August 31, 2023 (THOMMEN SB AC32/07 Revision 1.0).
(2) Serviceable part: Any AC32.(X) Digital ADC that is not an
affected part; or an affected part where the power module has been
replaced by THOMMEN, in accordance with the instructions of THOMMEN
SB AC32/07 Revision 1.0.
(3) Group 1 aircraft: Have an affected part installed.
(4) Group 2 aircraft: Do not have an affected part installed but
are eligible for AC32.(X) Digital ADC installation.
(g) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(h) Required Actions
For Group 1 aircraft: Within 12 months after the effective date
of this AD, remove each affected part from service and replace it
with a serviceable part in accordance with paragraph 3.A. of the
Accomplishment Instructions in THOMMEN SB AC32/07 Revision 1.0,
except where this material specifies to send the removed affected
part to the manufacturer, this AD does not require that action.
(i) Parts Installation Prohibition
For Group 1 and 2 aircraft: As of the effective date of this AD,
do not install an affected part on any aircraft.
(j) Special Flight Permits
A one-time special flight permit may be issued in accordance
with 14 CFR 21.197 and 21.199 in order to fly to a maintenance base
to perform the required action in this AD, provided a flight profile
above -15 degrees Celsius (5 degrees Fahrenheit) is maintained.
(k) 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 International Validation Branch, send it to the
attention of the person identified in paragraph (l) of this AD and
email to: [email protected]. Before using any approved AMOC, notify your
appropriate principal inspector, or lacking a principal inspector,
the manager of the responsible Flight Standards Office.
(l) Additional Information
For more information about this AD, contact William Reisenauer,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (516) 228-7301; email: [email protected].
(m) 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) THOMMEN AIRCRAFT EQUIPMENT Service Bulletin SB AC32/07,
Revision 1.0, dated August 31, 2023.
(ii) [Reserved]
(3) For THOMMEN AIRCRAFT EQUIPMENT material in this AD, contact
THOMMEN AIRCRAFT EQUIPMENT AG, Hofackerstrasse 48, 4132 Muttenz,
Switzerland; phone: +41 (0) 61 965 22 22; email: [email protected];
website: thommen.aero.
(4) You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 901 Locust, Kansas
City, MO 64106. 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 March 27, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-06066 Filed 4-9-25; 8:45 am]
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