DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-1038; Product Identifier 2017-CE-024-AD; Amendment
39-19197; AD 2018-04-02]
RIN 2120-AA64

Airworthiness Directives; Viking Air Limited Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for Viking
Air Limited Models DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-
400 airplanes. This AD results from mandatory continuing airworthiness
information (MCAI) issued by an aviation authority of another country
to identify and address an unsafe condition on an aviation product. The
MCAI describes the unsafe condition as aileron cable wear; fouling at
the wing root rib, fuselage skin, and wing root rib fairlead; and/or
fraying of the cable from the root rib fairlead. We are issuing this AD
to require actions to address the unsafe condition on these products.

DATES: This AD is effective March 27, 2018.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in the AD as of March 27,
2018.

ADDRESSES: You may examine the AD docket on the internet at http://www.
regulations.gov by searching for and locating Docket No. FAA-2017-
1038; or in person at Docket Operations, U.S. Department of
Transportation, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
For service information identified in this AD, contact Viking Air
Limited Technical Support, 1959 De Havilland Way, Sidney, British
Columbia, Canada, V8L 5V5; telephone: (North America) (866) 492-8527;
fax: (250) 656-0673; email: technical.support@vikingair.com; internet:
http://www.vikingair.com/support/service-bulletins. You may view this
referenced service information at the FAA, Policy and Innovation
Division, 901 Locust, Kansas City, Missouri 64106. For information on
the availability of this material at the FAA, call (816) 329-4148. It
is also available on the internet at http://www.regulations.gov by
searching for Docket No. FAA-2017-1038.

FOR FURTHER INFORMATION CONTACT: James Delisio, Program Manager,
Continued Operational Safety, FAA, New York ACO Branch, 1600 Stewart
Avenue, Westbury, New York 11590; telephone: (516) 228-7300; fax: (516)
794-5531; email: 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to Viking Air Limited Models
DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300, and DHC-6-400 airplanes. The
NPRM was published in the Federal Register on November 6, 2017 (82 FR
51367). The NPRM proposed to correct an unsafe condition for the
specified products and was based on mandatory continuing airworthiness
information (MCAI) originated by an aviation authority of another
country.
The MCAI states:

There have been reports of accelerated aileron cable wear
because of contact with the fuselage skin cut-out or the wing root
rib. Wear that is not detected can lead to failure of the aileron
cable and loss of control of the aeroplane.
The root cause of this problem has not yet been identified. This
[Transport Canada] AD requires inspection of the aeroplane and
reporting of the inspection results to Viking Air Ltd. This
[Transport Canada] AD is considered an interim action and further AD
action may follow.
Aileron cables are typically replaced at intervals of 60 months
in accordance with the DHC-6 maintenance schedule.

The MCAI can be found in the AD docket on the internet at: https://www.regulations.gov/document?D=FAA-2017-1038-0002.

Comments

We gave the public the opportunity to participate in developing
this AD. The following presents the comment received on the proposal
and the FAA's response to the comment.

Request a Change to the Corrective Actions

Mathew Carlson stated the proposed actions are not necessary.
Although the root cause has not yet been determined, the cause appears
obvious and the appropriate actions to take are obvious as well. The
commenter stated they believe the corrective actions proposed are
unnecessary, and the root cause is an alignment issue between pulleys
and the fuselage cutout. The commenter believes the corrective action
should be to trim the fuselage cutout for better clearance and to not
require the repetitive inspections.
We do not agree with the commenter. While it is possible the
commenter's root cause/solution is correct, we disagree that the cable
inspection and/or replacement has no benefit. Until enough information
is gathered and analyzed to accurately determine the root cause of the
issue, the repetitive inspection (and replacement if necessary) is the
action necessary to address the unsafe condition and provide a safe
method to continue airplane operation.
We have not changed this AD based on this comment.

Conclusion

We reviewed the relevant data, considered the comment received, and
determined that air safety and the public interest require adopting the
AD as proposed except for minor editorial changes. We have determined
that these minor changes:
Are consistent with the intent that was proposed in the
NPRM for correcting the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.

Related Service Information Under 1 CFR Part 51

Viking Air Limited issued DHC-6 Twin Otter Service Bulletin Number:
V6/0022, Revision B, dated June 13, 2014. The service information
describes procedures for initial and repetitive inspections of the aileron cable
for aileron cable wear; fouling at the wing root rib, fuselage skin,
and wing root rib fairlead; and/or fraying of the cable from the root
rib fairlead; and replacement of the aileron cables as necessary. 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 of the AD.

Costs of Compliance

We estimate that this AD will affect 141 products of U.S. registry.
We also estimate that it would take about 20 work-hours per product to
comply with the basic requirements of this AD. The average labor rate
is $85 per work-hour.
Based on these figures, we estimate the cost of this AD on U.S.
operators to be $239,700, or $1,700 per product.
In addition, the following is an estimate of possible necessary
follow-on replacement actions. We have no way of determining the number
of products that may need these actions.

* Work-hours includes access, testing, and close-up.

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 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 current valid OMB control number. The control
number for the collection of information required by this proposed AD
is 2120-0056. The paperwork cost associated with this proposed AD has
been detailed in the Costs of Compliance section of this document and
includes time for reviewing instructions, as well as completing and
reviewing the collection of information. Therefore, all reporting
associated with this proposed AD is mandatory. Comments concerning the
accuracy of this burden and suggestions for reducing the burden should
be directed to the FAA at 800 Independence Ave. SW, Washington, DC
20591. ATTN: Information Collection Clearance Officer, AES-200.

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.
We are 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.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to small airplanes, gliders,
balloons, airships, domestic business jet transport airplanes, and
associated appliances to the Director of the Policy and Innovation
Division.

Regulatory Findings

We 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2017-
1038; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
the NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations (telephone (800)
647-5527) is in the ADDRESSES section. Comments will be available in
the AD docket shortly after receipt.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of 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 AD: