Rule2025-16190
Airworthiness Directives; Viking Air Limited (Type Certificate Previously Held by Bombardier Inc. and de Havilland, Inc.) Airplanes
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
August 25, 2025
Effective
September 29, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is superseding Airworthiness Directive (AD) 2022-23- 08, which applied to all Viking Air Limited (Viking) Model DHC-3 airplanes. AD 2022-23-08 required a visual inspection of the stabilizer actuator to confirm that the stabilizer actuator lock ring is present, correctly seated in the groove in the upper housing, and engaged in the clamp nut, applicable corrective actions, application of a torque seal, and sending the inspection results to the FAA. Since the FAA issued AD 2022-23-08, Transport Canada, which is the aviation authority for Canada, issued mandatory continuing airworthiness information (MCAI) to address the unsafe condition identified as a missing stabilizer actuator lock ring. This AD requires repetitively inspecting the stabilizer actuator to confirm that the stabilizer actuator lock ring is present, correctly seated in the groove in the upper housing, and engaged in the clamp nut; taking applicable corrective actions; applying a witness mark (torque seal); and installing a secondary retention feature as terminating action for the repetitive inspections. This AD also prohibits installing any stabilizer actuator unless it is a serviceable part. 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 162 (Monday, August 25, 2025)</title>
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[Federal Register Volume 90, Number 162 (Monday, August 25, 2025)]
[Rules and Regulations]
[Pages 41290-41293]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-16190]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-1107; Project Identifier MCAI-2024-00784-A;
Amendment 39-23118; AD 2025-17-08]
RIN 2120-AA64
Airworthiness Directives; Viking Air Limited (Type Certificate
Previously Held by Bombardier Inc. and de Havilland, Inc.) Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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[[Page 41291]]
SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2022-23-
08, which applied to all Viking Air Limited (Viking) Model DHC-3
airplanes. AD 2022-23-08 required a visual inspection of the stabilizer
actuator to confirm that the stabilizer actuator lock ring is present,
correctly seated in the groove in the upper housing, and engaged in the
clamp nut, applicable corrective actions, application of a torque seal,
and sending the inspection results to the FAA. Since the FAA issued AD
2022-23-08, Transport Canada, which is the aviation authority for
Canada, issued mandatory continuing airworthiness information (MCAI) to
address the unsafe condition identified as a missing stabilizer
actuator lock ring. This AD requires repetitively inspecting the
stabilizer actuator to confirm that the stabilizer actuator lock ring
is present, correctly seated in the groove in the upper housing, and
engaged in the clamp nut; taking applicable corrective actions;
applying a witness mark (torque seal); and installing a secondary
retention feature as terminating action for the repetitive inspections.
This AD also prohibits installing any stabilizer actuator unless it is
a serviceable part. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective September 29, 2025.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of September
29, 2025.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-1107; 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 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 Transport Canada material identified in this AD,
contact Transport Canada, Transport Canada National Aircraft
Certification, 159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, Canada;
phone: (888) 663-3639; email: <a href="/cdn-cgi/l/email-protection#c59186eb84acb7b2aab7b1adacaba0b6b681acb7a0a6b1acb3a0b6e886aaabb6aca2aba0b6a1a0aba4b3aca2a4a7aca9acb1a0eb918685b1a6eba2a6eba6a4"><span class="__cf_email__" data-cfemail="4014036e012932372f323428292e253333042932252334293625336d032f2e3329272e253324252e213629272122292c2934256e14030034236e27236e2321">[email protected]</span></a>; website: tc.canada.ca/en/aviation.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-1107.
FOR FURTHER INFORMATION CONTACT: Brenda Buitrago, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (516) 228-7368; email: <a href="/cdn-cgi/l/email-protection#492b3b2c272d286725672b3c203d3b282e2667392c3b2c33092f2828672e263f"><span class="__cf_email__" data-cfemail="aac8d8cfc4cecb84c684c8dfc3ded8cbcdc584dacfd8cfd0eacccbcb84cdc5dc">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2022-23-08, Amendment 39-22235 (87 FR
66084, November 2, 2022) (AD 2022-23-08). AD 2022-23-08 applied to
Viking Model DHC-3 airplanes, all serial numbers.
AD 2022-23-08 required a visual inspection of the stabilizer
actuator to confirm that the stabilizer actuator lock ring is present,
correctly seated in the groove in the upper housing, and engaged in the
clamp nut, applicable corrective actions, application of a torque seal,
and sending the inspection results to the FAA. The FAA issued AD 2022-
23-08 to correct an unsafe condition identified as a missing stabilizer
actuator lock ring.
The NPRM was published in the Federal Register on June 20, 2025 (90
FR 26228). The NPRM was prompted by Transport Canada AD CF-2024-46,
dated December 23, 2024 (Transport Canada AD CF-2024-46) (also referred
to as the MCAI).
The MCAI states that a fatal DHC-3 airplane accident occurred on
September 4, 2022, at Mutiny Bay, near Freeland, WA. Witnesses reported
that the airplane was in level flight before it entered a slight climb,
then pitched down in a near-vertical descent until it impacted water
resulting in fatal injuries to the pilot and the nine passengers.
The MCAI also states that the National Transportation Safety Board
(NTSB) carried out the accident investigation and released a final
investigation report on September 29, 2023. The NTSB noted in the
report that the stabilizer actuator clamp nut on the accident airplane
separated from the stabilizer barrel by unthreading and the lock ring
securing the clamp nut to the barrel was missing. The NTSB also found
an unapproved moisture seal had been installed on the stabilizer
actuator, which is not part of the airplane's type design, leading to
increased rotational friction between the clamp nut and eye bolt, which
has the potential to increase the rate of separation between the clamp
nut and barrel in the absence of the lock ring.
To address the unsafe condition, Transport Canada AD CF-2024-46
requires initial and repetitive inspections of the stabilizer actuator
to confirm that the stabilizer actuator lock ring is present, correctly
seated in the groove in the upper housing, and fully engaged in the
clamp nut. Transport Canada AD CF-2024-46 also requires application of
a witness mark (torque seal) and prohibits the installation of a
stabilizer actuator that has not been inspected in accordance with
Transport Canada AD CF-2024-46 or has not been marked. If the lock ring
is missing or incorrectly installed, Transport Canada AD CF-2024-46
requires the rectification of the actuator in accordance with Viking
Service Letter DHC3-SL-27-001, dated October 25, 2022, or replacement
with a serviceable actuator, and prohibits the installation of affected
parts.
In the NPRM, the FAA proposed to retain none of the requirements of
AD 2022-23-08. Instead, the FAA proposed to require accomplishing the
actions specified in Transport Canada AD CF-2024-46 except for any
differences identified as exceptions in the regulatory text of this AD.
See ``Differences Between this AD and the MCAI'' for a general
discussion of these differences.
The FAA is issuing this AD to ensure that the stabilizer actuator
clamp nut does not separate from the stabilizer barrel by unthreading
and to ensure that the lock ring securing the clamp nut to the
stabilizer barrel does not separate. This condition, if not detected
and corrected, could result in a reduction or loss of pitch control
during flight with consequent loss of control of the airplane.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-1107.
Discussion of Final Airworthiness Directive
Comments
The FAA received no comments on the NPRM or on the determination of
the costs.
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
[[Page 41292]]
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. This AD is adopted as proposed
in the NPRM.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Transport Canada AD CF-2024-46, which specifies
procedures for initial and repetitive inspections of the stabilizer
actuator, applicable corrective actions, and torque seal (witness mark)
application. Transport Canada AD CF-2024-46 also prohibits the
installation of any stabilizer actuator unless it is a serviceable
part.
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
Where Part V of Transport Canada AD CF-2024-46 specifies installing
a new clamp nut and safety wire on the horizontal stabilizer as an
optional terminating action, this AD requires installing a secondary
retention feature using a method approved by the FAA within 330 hours
time-in-service after the effective date of this AD.
Where Transport Canada AD CF-2024-46 requires reporting any
movement of the lock ring or witness mark to the Transport Canada Web
Service Difficulty Reporting System (WSDRS), this AD does not require
that action.
Costs of Compliance
The FAA estimates that this AD affects 64 airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this AD.
Estimated Costs
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Cost on U.S.
Action Labor cost Parts cost Cost per product operators
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Inspect lock ring................ 1 work-hour x $85 $0 $85 per inspection $5,440 per
per hour = $85 per cycle. inspection cycle.
inspection cycle.
Apply witness mark (torque seal). 1 work-hour x $85 0 $85................. $5,440.
per hour = $85.
Install secondary retention 17 work-hours x $85 795 $2,240.............. $143,360.
feature. per hour = $1,445.
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The FAA estimates the following costs to do any necessary actions
that are required based on the results of the inspection. The agency
has no way of determining the number of airplanes that might need these
actions:
On-Condition Costs
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Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Install lock ring if missing or incorrectly 15 work-hours x $85 per hour = $50 $1,325
installed. $1,275.
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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 has determined that 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:
0
a. Removing Airworthiness Directive 2022-23-08, Amendment 39-22235 (87
FR 66084, November 2, 2022); and
0
b. Adding the following new airworthiness directive:
2025-17-08 Viking Air Limited (type certificate previously held by
Bombardier Inc. and de Havilland, Inc.): Amendment 39-23118; Docket
No. FAA-2025-1107; Project Identifier MCAI-2024-00784-A.
(a) Effective Date
This airworthiness directive (AD) is effective September 29,
2025.
(b) Affected ADs
This AD replaces AD 2022-23-08, Amendment 39-22235 (87 FR 66084,
November 2, 2022).
[[Page 41293]]
(c) Applicability
This AD applies to Viking Air Limited (Viking) (type certificate
previously held by Bombardier Inc. and de Havilland, Inc.) Model
DHC-3 airplanes, certificated in any category, as identified in
Transport Canada AD CF-2024-46, dated December 23, 2024 (Transport
Canada AD CF-2024-46).
(d) Subject
Joint Aircraft System Component (JASC) Code 5520, Elevator
Structure.
(e) Unsafe Condition
This AD was prompted by an investigation of a Viking Model DHC-3
airplane where the lock ring of the stabilizer actuator was found to
be missing. The FAA is issuing this AD to ensure that the stabilizer
actuator clamp nut does not separate from the stabilizer barrel by
unthreading and to ensure that the lock ring securing the clamp nut
to the stabilizer barrel does not separate. This condition, if not
detected and corrected, could result in a reduction or loss of pitch
control during flight with consequent loss of control of the
airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
Except as specified in paragraph (h) of this AD: Comply with all
required actions and compliance times specified in, and in
accordance with, Transport Canada AD CF-2024-46.
(h) Exceptions to Transport Canada AD CF-2024-46
(1) Where Transport Canada AD CF-2024-46 refers to its effective
date, this AD requires using the effective date of this AD.
(2) Where Transport Canada AD CF-2024-46 requires compliance in
terms of hours air time, this AD requires using hours time-in-
service (TIS).
(3) Where Part V of Transport Canada AD CF-2024-46 specifies
installing a new clamp nut and safety wire on the horizontal
stabilizer as an optional terminating action using FAA Supplemental
Type Certificate SA02761SE, this AD requires installing a secondary
retention feature using a method approved by the FAA within 330
hours time-in-service after the effective date of this AD.
(4) Where Transport Canada AD CF-2024-46 requires reporting any
movement of the lock ring or witness mark to the Transport Canada
Web Service Difficulty Reporting System (WSDRS), this AD does not
require that action.
(i) 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, mail
it to the address identified in paragraph (j) of this AD and email
to: <a href="/cdn-cgi/l/email-protection#cf8e82808c8fa9aeaee1a8a0b9"><span class="__cf_email__" data-cfemail="1e5f53515d5e787f7f30797168">[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.
(j) Additional Information
For more information about this AD, contact Brenda Buitrago,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (516) 228-7368; email:
<a href="/cdn-cgi/l/email-protection#7f1d0d1a111b1e5113511d0a160b0d1e1810510f1a0d1a053f191e1e51181009"><span class="__cf_email__" data-cfemail="640616010a00054a084a06110d101605030b4a140116011e240205054a030b12">[email protected]</span></a>.
(k) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference (IBR) 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) Transport Canada AD CF-2024-46, dated December 23, 2024.
(ii) [Reserved]
(3) For Transport Canada material identified in this AD, contact
Transport Canada, Transport Canada National Aircraft Certification,
159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, Canada; phone: (888)
663-3639; email: <a href="/cdn-cgi/l/email-protection#beeafd90ffd7ccc9d1cccad6d7d0dbcdcdfad7ccdbddcad7c8dbcd93fdd1d0cdd7d9d0dbcddadbd0dfc8d7d9dfdcd7d2d7cadb90eafdfecadd90d9dd90dddf"><span class="__cf_email__" data-cfemail="b7e3f499f6dec5c0d8c5c3dfded9d2c4c4f3dec5d2d4c3dec1d2c49af4d8d9c4ded0d9d2c4d3d2d9d6c1ded0d6d5dedbdec3d299e3f4f7c3d499d0d499d4d6">[email protected]</span></a>; website: tc.canada.ca/en/
aviation.
(4) You may view this material at 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 <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#e68094c88f8895968385928f8988a688879487c8818990"><span class="__cf_email__" data-cfemail="7b1d09551215080b1e180f1214153b151a091a551c140d">[email protected]</span></a>.
Issued on August 20, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-16190 Filed 8-22-25; 8:45 am]
BILLING CODE 4910-13-P
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