90 FR 117 pgs. 26228-26231 - Airworthiness Directives; Viking Air Limited (Type Certificate Previously Held by Bombardier Inc. and de Havilland, Inc.) Airplanes
Type: PRORULEVolume: 90Number: 117Pages: 26228 - 26231
Pages: 26228, 26229, 26230, 26231Docket number: [Docket No. FAA-2025-1107; Project Identifier MCAI-2024-00784-A]
FR document: [FR Doc. 2025-11327 Filed 6-18-25; 8:45 am]
Agency: Transportation Department
Sub Agency: Federal Aviation Administration
Official PDF Version: PDF Version
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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]
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:
Notice of proposed rulemaking (NPRM).
SUMMARY:
[top] The FAA proposes to supersede Airworthiness Directive (AD) 2022-23-08, which applies to all Viking Air Limited (Viking) Model DHC-3 airplanes. AD 2022-23-08 requires a visual inspection of the stabilizer actuator to confirm that the stabilizer
DATES:
The FAA must receive comments on this NPRM by August 4, 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.
• 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-2025-1107; 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 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 Transport Canada material identified in this proposed AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, Canada; phone: (888) 663-3639; email: TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca; website: tc.canada.ca/en/aviation.
• 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.
FOR FURTHER INFORMATION CONTACT:
Brenda Buitrago, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (516) 228-7368; email: brenda.l.buitrago.perez@faa.gov.
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 ADDRESSES . Include "Docket No. FAA-2025-1107; Project Identifier MCAI-2024-00784-A" 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 Brenda Buitrago, 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
The FAA issued AD 2022-23-08, Amendment 39-22235 (87 FR 66084, November 2, 2022) (AD 2022-23-08), for Viking Model DHC-3 airplanes, all serial numbers, certificated in any category. The FAA issued AD 2022-23-08 to correct an unsafe condition identified as a missing stabilizer actuator lock ring.
AD 2022-23-08 requires 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 address the unsafe condition on these products.
Actions Since AD 2022-23-08 Was Issued
Since the FAA issued AD 2022-23-08, Transport Canada, which is the aviation authority for Canada, issued 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 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.
[top] 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
The FAA is proposing 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 regulations.gov under Docket No. FAA-2025-1107.
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 ADDRESSES .
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 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 retain none of the requirements of AD 2022-23-08. This proposed AD would require accomplishing the actions specified in Canadian AD CF-2024-46 described previously. See "Differences Between this Proposed AD and the MCAI" for a discussion of the general differences included in this proposed AD.
Differences Between This Proposed 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 proposed AD would require 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 proposed AD would not require that action.
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 Transport Canada 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 Transport Canada. As a result, the FAA proposes to incorporate Transport Canada AD CF-2024-46 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2024-46 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Material required by Transport Canada AD CF-2024-46 for compliance will be available at regulations.gov under Docket No. FAA-2025-1107 after the FAA final rule is published.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would affect 64 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
| Action | Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
|---|---|---|---|---|
| Inspect lock ring | 1 work-hour × $85 per hour = $85 per inspection cycle | $0 | $85 per inspection cycle | $5,440 per inspection cycle. |
| Apply witness mark (torque seal) | 1 work-hour × $85 per hour = $85 | 0 | $85 | $5,440. |
| Install secondary retention feature | 17 work-hours × $85 per hour = $1445 | 795 | $2,240 | $143,360. |
The FAA estimates the following costs to do any necessary actions that would be required based on the results of the proposed inspection. The agency has no way of determining the number of airplanes that might need these actions:
| Action | Labor cost | Parts cost | Cost per product |
|---|---|---|---|
| Install lock ring if missing or incorrectly installed | 15 work-hours × $85 per hour = $1,275 | $50 | $1,325 |
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.
[top] 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
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
1. The authority citation for part 39 continues to read as follows:
Authority:
49 U.S.C. 106(g), 40113, 44701.
§?39.13 [Amended]
2. The FAA amends §?39.13 by:
a. Removing Airworthiness Directive 2022-23-08, Amendment 39-22235 (87 FR 66084, November 2, 2022); and
b. Adding the following new airworthiness directive:
Viking Air Limited (type certificate previously held by Bombardier Inc. and de Havilland, Inc.): Docket No. FAA-2025-1107; Project Identifier MCAI-2024-00784-A.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive (AD) by August 4, 2025.
(b) Affected ADs
This AD replaces AD 2022-23-08, Amendment 39-22235 (87 FR 66084, November 2, 2022) (AD 2022-23-08).
(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-2022-68 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)
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: AMOC@faa.gov. 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: brenda.l.buitrago.perez@faa.gov.
(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: TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca; 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 www.archives.gov/federal-register/cfr/ibr-locations or email fr.inspection@nara.gov .
Issued on June 16, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.
[FR Doc. 2025-11327 Filed 6-18-25; 8:45 am]
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