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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2020-1003; Project Identifier MCAI-2020-00962-A]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Notice of proposed rulemaking (NPRM).

# SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Viking Air Limited (Viking) (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. This proposed AD results from 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 identifies the unsafe condition as cracks and corrosion damage to the aileron internal structure. This proposed AD would require visually inspecting the entire aileron internal structure, correcting any damage found, and reporting the inspection results to Viking. 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 7, 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-2020-1003; 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:

                        Deep Gaurav, Aviation Safety Engineer, New York ACO Branch, FAA, 1515 Stewart Avenue, Westbury, NY 11590; phone: (516) 228-7300; fax: (516) 794-5331; email:                         *deep.gaurav@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-2020-1003; Project Identifier MCAI-2020-00962-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 this 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 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 Deep Gaurav, Aviation Safety Engineer, New York ACO Branch, FAA, 1515 Stewart Avenue, 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

Transport Canada, which is the aviation authority for Canada, has issued Transport Canada AD CF-2020-05, dated March 13, 2020 (referred to after this as “the MCAI”), to address the unsafe condition on Viking Model DHC-6 series 1, DHC-6 series 100, DHC-6 series 110, DHC-6 series 200, DHC-6 series 210, DHC-6 series 300, DHC-6 series 310, DHC-6 series 320, and DHC-6 series 400 airplanes. The MCAI states:

                        Viking Air Ltd. (Viking) received reports of cracks and corrosion damage to the aileron internal structure. During a repair of an in-service aeroplane, an aileron hinge support rib was found cracked at the lower flange along the bend radius near the hinge fitting attachment at wing station 247.29. Preliminary investigation by Viking                               ( print page 3237)                            determined that the observed crack was the result of fatigue. During an inspection of another in-service aeroplane, the aileron inboard rib and the vertical flange of the inboard aileron forward spar near a fastener hole were also found cracked.                    

The current inspection requirements of the affected aeroplanes do not include a direct inspection of the aileron internal structure. Cracks or other damage to the aileron ribs or to the aileron spar flanges are not detectable from the aileron exterior surfaces. Undetected cracks or other damage to the aileron internal structure could lead to progressive looseness of the aileron at the hinge support rib push-pull rod attachment and subsequent flutter condition and degraded or loss of aileron control.

To detect and correct any cracking or other damage to the aileron internal structure, this [Transport Canada] AD mandates a one-time Special Detailed Inspection (SDI) of all aileron internal structure, including front and rear spars, all aileron ribs and upper and lower skins for cracks, corrosion or other damage, and rectification, as required, of the damaged parts.

This [Transport Canada] AD also mandates reporting of all inspection results to Viking. The reporting of the inspection results is necessary to assess the overall aileron internal structural condition on in-service aeroplanes and to determine additional corrective action based on the results of the inspections.

Viking has published Service Bulletin (SB) V6/0066 Revision A, dated 9 December 2019, (referred to as “the SB” in this AD) providing accomplishment instructions for the inspection, rectification of the damaged parts, and reporting requirements.

                    You may examine the MCAI in the AD docket at                     *https://www.regulations.gov*                     by searching for and locating Docket No. FAA-2020-1003.                

## Related Service Information Under 1 CFR Part 51

                    The FAA reviewed Viking DHC-6 Twin Otter Service Bulletin V6/0066, Revision A, dated December 9, 2019. The service information specifies procedures for visually inspecting the entire aileron internal structure, including front and rear spars, all aileron ribs, and upper and lower skins; repairing or replacing any damaged part; and reporting inspection results to Viking Air Limited technical support. 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 the                     **ADDRESSES**                     section.                

## Other Related Service Information

The FAA reviewed Viking DHC-6 Twin Otter Service Bulletin V6/0066, Revision NC, dated August 29, 2019. The service information specifies procedures for visually inspecting the aileron ribs, including ribs and both sides of the hinge arm; repairing or replacing any damaged part; and reporting inspection results to Viking Air Limited technical support.

## 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 in other products of the same type design.

## Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified in the service information described previously.

## Interim Action

The FAA considers that this proposed AD would be an interim action. The inspection reports will provide the FAA and Viking Air Limited additional data for determining the damage present in the fleet. After analyzing the data, the FAA may take further rulemaking action.

## Differences Between This Proposed AD and the MCAI

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 33 airplanes of U.S. registry. The FAA also estimates that it would take about 3 work-hours per airplane to comply with the inspection and 1 hour to comply with the reporting requirement of this proposed AD. The average labor rate is $85 per work-hour.

Based on these figures, the FAA estimates the cost of the proposed AD on U.S. operators would be $11,220 or $340 per airplane.

In addition, the FAA estimates that any necessary follow-on actions to replace an aileron would take 6 work-hours and require parts costing $52,243, for a cost of $52,753 per airplane. The FAA has no way of determining the number of airplanes that may need these actions.

## Paperwork Reduction Act

A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a currently valid OMB Control Number. The OMB Control Number for this information collection is 2120-0056. Public reporting for this collection of information is estimated to take approximately 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. All responses to this collection of information are mandatory. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to: Information Collection Clearance Officer, Federal Aviation Administration, 10101 Hillwood Parkway, Fort Worth, TX 76177-1524.

## 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                           ( print page 3238)                        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 this proposed regulation:

(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 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 

2. The FAA amends § 39.13 by adding the following new airworthiness directive: 

**Viking Air Limited (Type Certificate Previously Held by Bombardier Inc. and de Havilland, Inc.):**                         Docket No. FAA-2020-1003; Project Identifier MCAI-2020-00962-A.                    

## (a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by March 7, 2022.

## (b) Affected ADs

None.

## (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 5700, Wing Structure.

## (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 identifies the unsafe condition as cracks and corrosion damage to the aileron internal structure. The FAA is issuing this AD to detect and correct cracks and other damage to the aileron internal structure. The unsafe condition, if not addressed, could result in progressive looseness of the aileron at the hinge support rib push-pull rod attachment, flutter condition, and degraded or loss of aileron control, which could lead to loss of control of the airplane.

## (f) Compliance

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

## (g) Inspection and Replacement of the Aileron

At the compliance time specified in paragraph (g)(1) or (2) of this AD, inspect the left-hand (LH) and right-hand (RH) aileron internal structures for cracks, corrosion, and other damage and take any necessary corrective actions in accordance with the Accomplishment Instructions, steps II.A. through II.A.3. of Viking DHC-6 Twin Otter Service Bulletin V6/0066, Revision A, dated December 9, 2019 (Viking SB V6/0066, Revision A).

(1) For each LH or RH aileron that has accumulated 16,000 or more hours time-in-service (TIS), 32,000 or more flight cycles (FC), or 10 or more years since first installation on an airplane, whichever occurs first: Within 6 months after the effective date of this AD.

(2) For each LH or RH aileron that has accumulated less than 16,000 hours TIS, less than 32,000 FC, and less than 10 years since first installation on an airplane: Within 6 months after accumulating 16,000 hours TIS, 32,000 FC, or 10 years, whichever occurs first.

## (h) Reporting Requirement

Within 30 days after the inspection required by paragraph (g)(1) or (2) of this AD or within 30 days after the effective date of this AD, whichever occurs later, report to Viking the information requested on the Inspection Reply Form, page 7, of Viking SB V6/0066, Revision A.

## (i) Credit for Previous Actions

You may take credit for the actions required by paragraphs (g)(1) and (2) of this AD if you performed those actions before the effective date of this AD using Viking DHC-6 Twin Otter Service Bulletin V6/0066, Revision NC, dated August 29, 2019.

## (j) 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 (k)(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.

## (k) Related Information

                        (1) For more information about this AD, contact Deep Gaurav, Aviation Safety Engineer, New York ACO Branch, FAA, 1515 Stewart Avenue, Westbury, NY 11590; phone: (516) 228-7300; fax: (516) 794-5331; email:                         *deep.gaurav@faa.gov.*

                        (2) Refer to Transport Canada AD CF-2020-05, dated March 13, 2020, 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-2020-1003.                    

                        (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 review this referenced 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.                    

Issued on January 13, 2022.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2022-00994 Filed 1-20-22; 8:45 am]

BILLING CODE 4910-13-P