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:

The FAA proposes to supersede Airworthiness Directive (AD) AD 89-24-06 R1, which applies to all Boeing of Canada, Ltd. and de Havilland (now Viking Air Limited) Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes. This AD requires repetitively inspecting the elevator quadrant for damage and taking corrective action as necessary. Since the FAA issued AD 89-24-06 R1, the aviation authority for Canada revised its mandatory continuing airworthiness information (MCAI) to correct this unsafe condition on these products. The MCAI identifies the unsafe condition as damage to the flight control system. This proposed AD would retain the actions of AD 89-24-06 R1, extend the compliance time intervals for the repetitive inspections, add the Model DHC-6-400 airplane to the applicability, and add a fluorescent penetrant inspection requirement. The FAA is proposing this AD to address the unsafe condition on these products.

DATES:

The FAA must receive comments on this proposed AD by March 28, 2022.

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 https://www.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.

For service information identified in this NPRM, contact Viking Air Ltd., 1959 de Havilland Way, Sidney British Columbia, Canada V8L 5V5; phone: (800) 663-8444; email: continuing.airworthiness@vikingair.com; website: https://www.vikingair.com. You may view this service information 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.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2022-0099; 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 MCAI, any comments received, and other information. The street address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT:

Darren Gassetto, Aviation Safety Engineer, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (516) 228-7323; email: 9-avs-nyaco-cos@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-2022-0099; Project Identifier 2019-CE-019-AD” 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 https://www.regulations.gov,, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this proposed AD.

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 Darren Gassetto, Aviation Safety Engineer, FAA, New York ACO Branch, 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 89-24-06 R1, Amendment 39-6670 (55 FR 29347, July 19, 1990) (AD 89-24-06 R1) for all Boeing of Canada, Ltd. and de Havilland (type certificate currently held by Viking Air Limited) Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes. AD 89-24-06 R1 requires repetitively inspecting the elevator quadrant, P/N C6CFM 1138-27 (Pre Mod 6/1394), P/N C6CFM 1450-27 (Post Mod 6/1394 or production cut-in (PCI) S/N 331, Pre Mod 6/1678), or P/N C6CFM 1450-29 (Post Mod 6/1678 or PCI S/N 602), for distortion (warping, buckling, and score marks on the quadrant topside face caused by rubbing against the side of the cable guard) and replacing if distortion is found. AD 89-24-06 R1 also requires inspecting the elevator quadrant mounting support bracket, P/N C6CFM 1142-1, for cracks if distortion in the elevator quadrant is found and replacing any cracked P/N C6CFM 1142-1.

Actions Since AD 89-24-06 R1 Was Issued

Since the FAA issued AD 89-24-06 R1, the type certificate holder for Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes changed from de Havilland to Viking Air Limited. In 2012, the FAA issued Viking Air Limited a type certificate for the Model DHC-6-400 airplane as part of the DHC-6 series.

Transport Canada, which is the aviation authority for Canada, superseded its prior ADs on this unsafe condition and issued Canadian AD CF-1972-06R5, dated June 22, 2018 (referred to after this as “the MCAI”), to require a fluorescent penetrant inspection and expand the model applicability to include the Viking Air Limited Model DHC-6-400 airplane. The MCAI states:

Damage to the flight control system of DHC-6 aeroplanes was found during inspection. The damage has been attributed to ground gusts. The damage included cracks in the base of the lower control column, cracks and buckles in the elevator/rudder pulley bracket, and distortion of the elevator quadrant. Damage to the elevator quadrant may produce abnormal loads on the quadrant support bracket that damage the bracket.

Damaged flight control components may fail when subjected to service loads, resulting in loss of control of the aeroplane.

This revision of the [Transport Canada] AD clarifies the applicability of the corrective actions and endorses Service Bulletin (SB) 6/511 as a means of accomplishing some of the required inspections. In corrective action Part III, dye penetrant inspection has been replaced by fluorescent penetrant inspection.

You may examine the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2022-0099.

Related Service Information Under 1 CFR Part 51

The FAA reviewed DHC-6 (Twin Otter) Service Bulletin 6-511, Revision A, dated June 22, 1990. This service bulletin specifies procedures for repetitively inspecting the elevator quadrant for distortion (warping, buckling, and score marks), performing a one-time dye penetrant inspection of the elevator quadrant support bracket for cracks, and taking corrective actions. This service information 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

This product has been approved by the aviation authority of another country and is 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 and service information referenced above. The FAA is issuing this NPRM after determining 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 the actions of AD 89-24-06 R1, extend the compliance time intervals for the repetitive inspections, add the Model DHC-6-400 airplane to the applicability, and add a fluorescent penetrant inspection requirement with credit for the visual inspections done before the effective date of this proposed AD.

Differences Between This Proposed AD and the MCAI

The MCAI addresses actions on the the control column lower assembly, the elevator pulley bracket system, and the elevator quadrant. This proposed AD would only require actions on the elevator quadrant and elevator quadrant support bracket. The FAA is not proposing to require the repetitive inspections of the control column lower sub-assembly, lower horizontal torque tube, and top and bottom channels of the pulley bracket assembly, and the modifications that terminate those inspections, because those actions are addressed by AD 69-05-01 R2, Amendment 39-3824 (45 FR 45258, July 3, 1980) and AD 69-08-12 R1, Amendment 39-867 (34 FR 18226, November 14, 1969).

The MCAI applies to Viking Air Limited Model DHC-6 series 110, DHC-6 series 210, DHC-6 series 310, and DHC-6 series 320, and this proposed AD would not because these models do not have an FAA type certificate. Transport Canada Model DHC-6 series 1, DHC-6 series 100, DHC-6 series 200, DHC-6 series 300, and DHC-6 series 400 airplanes correspond to FAA Model DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-400 airplanes, respectively.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 133 airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

The FAA estimates the following costs to do any repairs or replacements that would be required based on the results of the proposed inspections. The FAA has no way of determining the number of airplanes that might need these repairs/replacements:

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 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.

2. The FAA amends § 39.13 by:

a. Removing Airworthiness Directive 89-24-06 R1, Amendment 39-6670 ( 55 FR 29347, July 19, 1990); and

b. Adding the following new airworthiness directive:

Viking Air Limited (Type Certificate previously held by Bombardier Inc., de Havilland, Inc.): Docket No. FAA-2022-0099; Project Identifier 2019-CE-019-AD.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by March 28, 2022.

(b) Affected ADs

This AD replaces Airworthiness Directive (AD) 89-24-06 R1, Amendment 39-6670 (55 FR 29347, July 19, 1990) (AD 89-24-06 R1).

(c) Applicability

This AD applies to Viking Air Limited (type certificate previously held by Bombardier Inc. and de Havilland, Inc.) Model DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-400 airplanes, all serial numbers, certificated in any category.

(d) Subject

Joint Aircraft System Component (JASC) Code 2700, Flight Control System.

(e) Unsafe Condition

This AD was prompted by mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as damage to the flight control system. The FAA is issuing this AD to prevent failure of the flight control system. The unsafe condition, if not addressed, could result in loss of control of the airplane.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Elevator Quadrant and Support Brackets: Inspections, Replacements, and Modifications

(1) Visually inspect the elevator quadrant for indications of distortion (warping, buckling, or score marks) by following paragraphs III.A.2.(a) and III.A.2.(b) of the Accomplishment Instructions in DHC-6 (Twin Otter) Service Bulletin 6-511, Revision A, dated June 22, 1990 (DHC-6 SB 6-511, Revision A) at the following applicable compliance times:

(i) For Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes, before further flight after the effective date of this AD or within 400 hours time-in-service (TIS) after the last inspection required by AD 89-24-06 R1, whichever occurs later, and thereafter at intervals not to exceed 400 hours TIS; or

(ii) For Model DHC-6-400 airplanes, before further flight after the effective date of this AD and thereafter at intervals not to exceed 400 hours TIS.

Note 1 to paragraph (g)(1): The elevator quadrant may be identified as P/N C6CFM1138-27 (Pre Mod 6/1394), P/N C6CFM1450-27 (Post Mod 6/1394 or production cut-in (PCI) S/N 331, Pre Mod 6/1678), or P/N C6CFM1450-29 (Post Mod 6/1678 or PCI S/N 602), and is referred to as assembly P/N C6CF1137-1, -3, -5, or -7.

(2) If any indication of distortion is found on the elevator quadrant during any inspection required by paragraph (g)(1) of this AD, before further flight, replace the elevator quadrant with a serviceable part and inspect the elevator quadrant support bracket assembly for cracks by following paragraphs III.B.1. through III.B.4.(b) of the Accomplishment Instructions in DHC-6 SB 6-511, Revision A. This AD requires that you do a fluorescent penetrant inspection as the type of required dye penetrant inspection. If a crack is found in the elevator quadrant support bracket, before further flight, replace with a serviceable part by following paragraphs III.B.5 through III.B.12 of the Accomplishment Instructions in DHC-6 SB 6-511, Revision A.

(3) For Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes: Within 400 hours TIS after the effective date of this AD, unless already done within the preceding 12 months before the effective date of this AD, inspect the elevator quadrant support bracket assembly for cracks by following paragraphs III.B.1. through III.B.4.(b) of the Accomplishment Instructions in DHC-6 SB 6-511, Revision A. This AD requires that you do a fluorescent penetrant inspection as the type of required dye penetrant inspection. If a crack is found in the elevator quadrant support bracket, before further flight, replace with a serviceable part by following paragraphs III.B.5 through III.B.12 of the Accomplishment Instructions in DHC-6 SB 6-511, Revision A.

(h) Credit for Previous Actions

(1) For Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes: This paragraph provides credit for the inspection required by paragraph (g)(1) of this AD if you performed the inspection before the effective date of this AD using paragraph (a)(1) of AD 89-24-06 R1.

(2) For Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes: This paragraph provides credit for the fluorescent penetrant inspection and subsequent replacement of the elevator quadrant support bracket due to a crack found from the fluorescent penetrant inspection required by paragraph (g)(2) of this AD if performed before the effective date of this AD using paragraphs (a)(3) and (4) of AD 89-24-06 R1.

(i) Alternative Methods of Compliance (AMOCs)

(1) The Manager, New York ACO 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 certification office, send it to the attention of the person identified in paragraph (j)(1) of this AD.

(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) Related Information

(1) For more information about this AD, contact Darren Gassetto, Aviation Safety Engineer, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (516) 228-7323; email: 9-avs-nyaco-cos@faa.gov.

(2) Refer to Transport Canada AD Number CF-1972-06R5, dated June 22, 2018, for more information. You may examine the Transport Canada AD in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2022-0099.

(3) For service information identified in this AD, contact Viking Air Ltd., 1959 de Havilland Way, Sidney British Columbia, Canada V8L 5V5; phone: (800) 663-8444; email: continuing.airworthiness@vikingair.com; website: https://www.vikingair.com. You may view this service information 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.