DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0217; Project Identifier MCAI-2020-01486-A;
Amendment 39-22041; AD 2022-10-03]
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.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain 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. 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 loose quadrants on the rudder pedal torque tube and signs
of loose rivets or rivet joint wear due to inadequate manufacturing
tolerances. This AD requires inspecting the rudder pedal torque tube
quadrant for looseness and taking corrective action as necessary. The
FAA is issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective June 23, 2022.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of June 23,
2022.

ADDRESSES: For service information identified in this final rule,
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. It is also available at
https://www.regulations.gov by searching for and locating Docket No.
FAA-2021-0217.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0217; 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.

FOR FURTHER INFORMATION CONTACT: Deep Gaurav, Aviation Safety Engineer,
New York ACO Branch, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; phone: (516) 228-7300; email: deep.gaurav@faa.gov.

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 serial-numbered
Viking Air Limited Model DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and
DHC-6-400 airplanes. The NPRM published in the Federal Register on
February 7, 2022 (87 FR 6802). The NPRM was prompted by MCAI originated
by Transport Canada, which is the aviation authority for Canada.
Transport Canada has issued AD CF-2020-45R1, dated April 16, 2021
(referred to after this as ``the MCAI''), to correct an unsafe
condition on Viking Air Limited 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,
serial numbers 001 through 987. The MCAI states:

There have been in-service reports of loose quadrants on the
rudder pedal torque tube and signs of loose rivets or rivet joint
wear, such as dark areas or streaks around the rivet heads and
quadrant to torque tube interface. Viking Air Ltd. has determined
that inadequate manufacturing tolerances may result in this
condition. This defect, if not detected and corrected, could result
in the affected parts deteriorating until the rivets fail, leading
to loss of control of the rudder and possible loss of control of the
aeroplane.
To detect and correct this condition, [Transport Canada] AD CF-
2020-45 mandated a one-time detailed inspection of the rudder pedal
torque tube quadrant assembly, and rectification, as required, of
the affected parts.
Viking Air Ltd. had published Service Bulletin (SB) V6/0067,
Revision NC, dated 16 July 2020, providing Accomplishment
Instructions for the one-time detailed inspection for looseness of
the affected parts. Since [Transport Canada] AD CF-2020-45 was
issued, Viking Air Ltd. has introduced a new rudder pedal torque
tube assembly in production that is not subject to the unsafe
condition of this [Transport Canada] AD. As a result, Viking Air
Ltd. has revised the SB V6/0067 at Revision A, dated 26 January 2021
(referred to as ``the SB'' in this [Transport Canada] AD) to update
the aeroplane serial number applicability.
This [Transport Canada] AD revision, CF-2020-45R1, is issued to
modify the aeroplane serial number applicability in accordance with
the SB.

You may examine the MCAI in the AD docket at https://www.regulations.gov
by searching for and locating Docket No. FAA-2021-0217.
In the NPRM, the FAA proposed to require inspecting the rudder
pedal torque tube quadrant for looseness and taking corrective action
as necessary. The FAA is issuing this AD to address the unsafe
condition on these products.

Discussion of Final Airworthiness Directive

Comments

The FAA received one comment from the Airline Pilots Association,
International (ALPA). ALPA supported the NPRM without change.

Conclusion

The FAA reviewed the relevant data, considered the comment
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.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Viking DHC-6 Twin Otter Service Bulletin V6/0067,
Revision A, dated January 26, 2021. This service information specifies
procedures for inspecting the rudder pedal torque tube quadrant for
looseness and performing a detailed visual inspection of the rudder
torque tube assembly for signs of loose rivets or rivet joint wear.
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 also reviewed Viking DHC-6 Twin Otter Service Bulletin V6/
0067, Revision NC, dated July 16, 2020. This service information
specifies procedures for inspecting the rudder pedal torque tube
quadrant for looseness and visually inspecting for signs of loose or
smoking rivets.

Differences Between This 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 airplanes, and
this AD would not because these models do not have an FAA type
certificate. Transport Canada Models 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 affects 33 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

The FAA estimates the following costs to replace the rudder pedal
torque tube quadrant assembly based on the results of the inspection.
The agency has no way of determining the number of airplanes that might
need this replacement:

On-Condition Costs

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

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]

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