DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0189; Product Identifier 2017-CE-022-AD; Amendment
39-19460; AD 2018-21-02]
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 Model DHC-3 airplanes. This AD results from mandatory
continuing airworthiness information (MCAI) issued 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 pitting corrosion on the shank of the wing strut attach
bolts. We are issuing this AD to require actions to address the unsafe
condition on these products.

DATES: This AD is effective November 28, 2018.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in the AD as of November 28,
2018.

ADDRESSES: You may examine the AD docket on the internet at http://
www.regulations.gov by searching for and locating Docket No. FAA-2018-
0189; or in person at Docket Operations, 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 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) (800) 663-8444;
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-2018-0189.

FOR FURTHER INFORMATION CONTACT: Aziz Ahmed, Aerospace Engineer, FAA,
New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, New York
11590; telephone: (516) 287-7329; fax: (516) 794-5531; email:
aziz.ahmed@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 Model
DHC-3 airplanes. The NPRM was published in the Federal Register on
March 13, 2018 (83 FR 10809). The NPRM proposed to correct an unsafe
condition for the specified products and was based on MCAI originated
by an aviation authority of another country. The MCAI states:

Pitting corrosion has been found on the shank of the following
part number wing strut attach bolts: C3W114-3, C3W129-3 and C3W128-
3. These bolts are manufactured using a standard AN12 bolt.
Metallurgical evaluation concluded that pitting corrosion was
present on the affected AN12 bolts prior to forming of the bolt head
and threads. The pitting and un-plated voids could cause a surface
condition that may have a detrimental effect on fatigue and
corrosion resistance, leading to bolt failure and consequent failure
of the wing.
Viking has not been able to confirm the affected batch numbers
or specific manufacture date range. New wing strut bolts
manufactured after 21 March 2016 are inspected for pitting during
manufacturing and issued new P/Ns C3W114-5, C3W129-5 and C3W128-5
under MOD 3/1010.

The MCAI can be found in the AD docket on the internet at: https://www.regulations.gov/document?D=FAA-2018-0189-0002.

Comments

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

Request To Issue SAIB Instead of an AD

Christopher Campbell requested that we withdraw the AD and issue a
special airworthiness information bulletin (SAIB) instead. The
commenter stated this AD is unnecessary and redundant since the
manufacturer has already addressed this issue with a mandatory service
bulletin and all affected bolts should now be removed. The commenter
stated the affected bolts are 3/4-inch diameter bolts and only the
surface cadmium plating is compromised, not the strength of the bolt.
The commenter also disagreed with the manufacturer that the compromised
cadmium plating would cause accelerated corrosion because the bolts are
treated with anti-corrosion grease on installation. The commenter
further stated an AD is unnecessary because the defect would be obvious
to any installing mechanic. Lastly, the commenter stated that the
proposed AD does little to further enhance safety but adds unwelcome
recordkeeping and cost for owners.
We do not agree. We concur with Transport Canada's finding of an
unsafe condition, as explained in Transport Canada AD No. CF-2017-11,
dated March 23, 2017. An SAIB would not be an appropriate solution. An
SAIB contains information and recommended actions that are voluntary
and not regulatory. Moreover, an SAIB is issued only for airworthiness
concerns that do not rise to the level of an unsafe condition.
Similarly, while an operator may incorporate the procedures described
in a manufacturer's service bulletin into its maintenance program, not
all operators are required to do so. For the corrective actions in a
service bulletin to become mandatory and to correct the unsafe
condition, the FAA must issue an AD. Based on the manufacturer's
metallurgical evaluation, the pitting corrosion was present on the
affected AN 12 bolts prior to forming of the bolt head and thread.
Corrosion pitting was found on airplanes when doing the inspections per
Transport Canada's AD CF-2017-11. Specifically, the pitting was
discovered on the bolt shanks of both wing strut fitting to wing spar
lug bolts. Relying on an assumption that the corrosion will be obvious
at the time of bolts installation, as suggested by the commenter, is
not a reliable method to correct an unsafe condition. We have not
changed this AD based on this comment.

Changes Made to This AD

We updated the service information in paragraphs (f)(1),
(2), and (3) of this AD to Viking Air Limited DHC-3 Otter Service
Bulletin Number V3/0006, Revision C, dated May 16, 2018, which adds
alternate part numbers for Post Mod 3/1010 wing strut bolts.
We changed paragraph (f)(2) of this AD to add alternate
wing strut bolt part numbers C3W114-9, C3W128-9, and C3W129-9 as
replacement bolts.
We updated paragraph (g) Credit for Actions Accomplished
in Accordance with Previous Service Information of this AD to add
Viking DHC-3 Otter SB Number: V3/0006, Revision B, dated March 9, 2017.

Conclusion

We reviewed the relevant data, considered the comment received, and
determined that air safety and the public interest require adopting the
AD with the changes described previously and minor editorial changes.
We have determined that these 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

We reviewed Viking Air Limited DHC-3 Otter Service Bulletin Number
V3/0006, Revision C, dated May 16, 2018. The service information
describes procedures for inspection and any necessary corrective action
for pitting of the wing strut shank bolts. 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.

Costs of Compliance

We estimate that this AD will affect 37 products of U.S. registry.
We also estimate that it would take about 4 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 $12,580, or $340 per product.
In addition, table 1 is an estimate of possible necessary follow-on
actions as a result of the required inspections. We have no way of
determining the number of products that may need these actions.
Replacing each affected bolt is on condition and is estimated to take
about 1 work-hour at $85 for a cost of $85 per bolt. We estimate that
any necessary follow-on replacement parts would cost as follows:

Table 1-Parts Replacement and Total Bolt Cost

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-2018-
0189; 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
airworthiness directive (AD):