DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1076; Project Identifier MCAI-2020-01201-A;
Amendment 39-22544; AD 2023-18-03]
RIN 2120-AA64

Airworthiness Directives; Viking Air Limited (Type Certificated
Previously Held by Bombardier Inc. and de Havilland, Inc.) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Viking Air Limited (Viking) (type certificate previously held by
Bombardier Inc. and de Havilland, Inc.) Model DHC-3 airplanes. This 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 describes
the unsafe condition as corrosion, wear, and fatigue-related
degradation in aging aircraft. This AD requires incorporating into the
existing maintenance records for your airplane the actions and
associated thresholds and intervals, including life limits, specified
in a supplemental inspection and corrosion control manual for Model
DHC-3 airplanes. This AD also requires completing all the initial tasks
identified in this manual and reporting corrosion findings to Viking.
The FAA is issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective October 24, 2023.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of October 24,
2023.

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2020-1076; 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.
Material Incorporated by Reference:

For service information identified in this final rule,
contact Viking Air Limited Technical Support, 1959 de Havilland Way,
Sidney, British Columbia, Canada V8L 5V5; phone: (800) 663-8444; fax:
(250) 656-0673; email: technical.support@vikingair.com; website:
vikingair.com/support/service-bulletins.
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
regulations.gov under Docket No. FAA-2020-1076.

FOR FURTHER INFORMATION CONTACT: Deep Gaurav, Aviation Safety Engineer,
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (516)
228-7321; email: 9-avs-nyaco-cos@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 all Viking Model DHC-3
airplanes. The NPRM published in the Federal Register on February 8,
2022 (87 FR 7059). The NPRM was prompted by AD CF-2018-04, dated
January 19, 2018, issued by Transport Canada, which is the aviation
authority for Canada (referred to after this as the MCAI). The MCAI
states that Viking developed a supplementary inspection and corrosion
control program for aging airplanes, which identifies specific
locations of an airplane that must be inspected to ensure corrosion-
related degradation does not result in an unsafe condition.
The MCAI requires doing all inspections specified in Part 2 of
Viking DHC-3 Otter Supplemental Inspection and Corrosion Control
Manual, PSM 1-3-5, Revision IR, dated December 21, 2017 (Viking PSM 1-
3-5, Revision IR), doing applicable corrective actions using Part 3 of
Viking PSM 1-3-5, Revision IR, and reporting to Viking Level 2 and
Level 3 corrosion as specified in Part 3 of Viking PSM 1-3-5, Revision
IR.
Corrosion, wear, and fatigue-related degradation, if not addressed,
could lead to structural failure with consequent loss of control of the
airplane.
In the NPRM, the FAA proposed to require establishing a corrosion
prevention and control program to identify and correct corrosion and
cracking. In the NPRM, the FAA also proposed to require completing all
of the initial tasks identified in the program and reporting corrosion
findings to Viking.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2020-1076.
The FAA issued a supplemental notice of proposed rulemaking (SNPRM)
to amend 14 CFR part 39 by adding an AD that would apply to all Viking
Model DHC-3 airplanes. The SNPRM published in the Federal Register on
June 28, 2023 (88 FR 41863). The SNPRM was prompted by the FAA's
decision to revise the proposed actions specified in the NPRM and to
reopen the comment period to allow the public the chance to comment on
whether the proposed AD would have a significant economic impact on a
substantial number of small entities. In the SNPRM, the FAA proposed to
require incorporating into the existing maintenance records for your
airplane the actions and associated thresholds and intervals, including
life limits, specified in Parts 2 and 3 of Viking PSM 1-3-5, Revision
IR, completing all the initial tasks identified in Viking PSM 1-3-5,
Revision IR, and reporting to Viking any Level 2 or Level 3 corrosion
findings. The FAA is issuing this AD to address the unsafe condition on
these products.

Discussion of Final Airworthiness Directive

Comments

The FAA received no comments on the SNPRM or on the determination
of the costs.

Conclusion

These products have been approved by the aviation authority of
another country and are 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 referenced above. The FAA reviewed the relevant data 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. Except for minor editorial changes, this AD is
adopted as proposed in the SNPRM.

ADs Mandating Airworthiness Limitations (ALS)

The FAA has previously mandated airworthiness limitations by
issuing ADs that require revising the ALS of the existing maintenance
manual or instructions for continued airworthiness to incorporate new
or revised inspections. This AD, however, requires establishing and
incorporating new inspections into the existing maintenance records
required by 14 CFR 91.417(a)(2) or 135.439(a)(2) for your airplane. The
FAA does not intend this as a substantive change. Requiring
incorporation of the new ALS requirements into the existing maintenance
records, rather than requiring individual repetitive inspections and
replacements, allows operators to record AD compliance once after
updating the existing maintenance records, rather than recording
compliance after every inspection and part replacement.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Viking PSM 1-3-5, Revision IR, which specifies
procedures for inspecting areas of the airplane that are particularly
susceptible to corrosion, wear, and fatigue-related degradation. Viking
PSM 1-3-5, Revision IR, also specifies repetitive inspection intervals,
defines the different levels of corrosion, and provides corrective
action if corrosion is found.
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.

Other Related Service Information

The FAA also reviewed Viking DHC-3 Otter Service Bulletin V3/0010,
Revision NC, dated March 19, 2020. The service bulletin provides a list
of new inspection tasks that have been added to the DHC-3 maintenance
program in Viking PSM 1-3-5, Revision IR.

Impact on Intrastate Aviation in Alaska

In light of the heavy reliance on aviation for intrastate
transportation in Alaska, the FAA has fully considered the effects of
this final rule (including costs to be borne by affected operators)
from the earliest possible stages of AD development. As previously
stated, 14 CFR part 39 requires operators to correct an unsafe
condition identified on an airplane to ensure operation of that
airplane in an airworthy condition. The FAA has determined that the
need to correct corrosion-related degradation in aging aircraft, which
could lead to structural failure with consequent loss of control of the
airplane, outweighs any impact on aviation in Alaska.

Costs of Compliance

The FAA estimates that this AD affects 68 airplanes of U.S.
registry. The FAA also estimates that it will take about 1 work-hour
per airplane at a labor rate of $85 per work-hour to revise the existing
maintenance records.
Based on these figures, the FAA estimates the cost of this AD on
U.S. operators to be $5,780 or $85 per airplane.
The FAA estimates it will take about 1 work-hour to report any
Level 2 corrosion found during the initial or subsequent inspections or
any Level 3 corrosion found during the initial or subsequent
inspections, for an estimated cost of $85 per airplane.

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 Flexibility Determination

The Regulatory Flexibility Act of 1980, Public Law 96-354, 94 Stat.
1164 (5 U.S.C. 601-612) (RFA) establishes as a principle of regulatory
issuance that agencies shall endeavor, consistent with the objectives
of the rule and of applicable statutes, to fit regulatory and
informational requirements to the scale of the businesses,
organizations, and governmental jurisdictions subject to regulation.
To achieve this principle, agencies are required to solicit and
consider flexible regulatory proposals and to explain the rationale for
their actions to assure that such proposals are given serious
consideration. The RFA covers a wide-range of small entities, including
small businesses, not-for-profit organizations, and small governmental
jurisdictions.
Agencies must perform a review to determine whether a rule will
have a significant economic impact on a substantial number of small
entities. If the agency determines that it will, the agency must
prepare a regulatory flexibility analysis as described in the RFA.
The FAA published an Initial Regulatory Flexibility Analysis (IRFA)
for this rule to aid the public in commenting on the potential impacts
to small entities. The FAA did not receive any public comments on the
IRFA. The purpose of this Final Regulatory Flexibility Analysis (FRFA)
is to provide the reasoning underlying the FAA's determination. A FRFA
must contain the following:
(1) A statement of the need for, and objectives of, the rule;
(2) A statement of the significant issues raised by the public
comments in response to the IRFA, a statement of the assessment of the
agency of such issues, and a statement of any changes made in the
proposed rule as a result of such comments;
(3) The response of the agency to any comments filed by the Chief
Counsel for Advocacy of the Small Business Administration (SBA) in
response to the proposed rule, and a detailed statement of any change
made to the proposed rule in the final rule as a result of the
comments;
(4) A description of and an estimate of the number of small
entities to which the rule will apply or an explanation of why no such
estimate is available;
(5) A description of the projected reporting, recordkeeping, and
other compliance requirements of the proposed rule, including an
estimate of the classes of small entities which will be subject to the
requirement and the type of professional skills necessary for
preparation of the report or record; and
(6) A description of the steps the agency has taken to minimize the
significant economic impact on small entities consistent with the
stated objectives of applicable statutes, including a statement of the
factual, policy, and legal reasons for selecting the alternative
adopted in the final rule and why each of the other significant
alternatives to the rule considered by the agency which affect the
impact on small entities was rejected.

1. Need for and Objectives of the Rule

The NPRM proposed to adopt a new AD for all Viking Model DHC-3
airplanes. This AD results from MCAI originated by an aviation
authority of another country to identify and correct an unsafe
condition on an aviation product.
The objective of this final rule is to require incorporating into
the existing maintenance records for your airplane the actions and
associated thresholds and intervals, including life limits, specified
in a supplemental inspection and corrosion control manual for Model
DHC-3 airplanes. This final rule also requires completing all the
initial tasks identified in this manual and reporting corrosion
findings to Viking.

2. Significant Issues Raised in Public Comments

The FAA received no public comments on the SNPRM.

3. Response to SBA Comments

The Chief Counsel for Advocacy of the SBA did not file any comments
in response to the proposed rule. Thus, the FAA did not make any
changes to the proposed rule in the final rule.

4. Description and Estimate of the Number of Small Entities

The RFA defines small entities as small businesses, small
governmental jurisdictions, or small organizations. In 5 U.S.C. 601(3),
the RFA defines ``small business'' to have the same meaning as ``small
business concern'' under section 3 of the Small Business Act. The Small
Business Act authorizes the SBA to define ``small business'' by issuing
regulations.
SBA (2022) has established size standards for various types of
economic activities, or industries, under the North American Industry
Classification System (NAICS).¹ These size standards generally define
small businesses based on the number of employees or annual receipts.
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¹Small Business Administration (SBA). 2022. Table of Size
Standards. Effective July 14, 2022. https://www.sba.gov/document/
support-table-size-standards.
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The FAA identified 68 de Havilland Model DHC-3 ``Otter'' airplanes
that would be affected by the final rule AD. These 68 airplanes are
registered to 32 private firms and 5 individuals. The individuals are
excluded from this analysis as they presumably are not small entities
under the RFA.
The 32 private firms own 63 airplanes. Of these firms, the FAA was
able to obtain the data necessary to classify 21 of them.² All but
one firm qualify as small entities under the RFA. Thus, the FAA
estimates that this rule would impact 20 small entities. For these 20
small entities, the results of the cost impact analysis are shown in
Table 1, ``Cost Impact on Small Entities.''
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²Firm revenue and employee count are drawn from online
sources, including: Dun & Bradstreet, Inc. (www.dnb.com); Manta
Media, Inc. (www.manta.com); Buzzfile Media, Inc.
(www.buzzfile.com); Datanyze, Inc. (www.datanyze.com); Moody's
Analytics (start.cortera.com); GeneralLiabilityInsure.com
(generalliabilityinsure.com); Kona Equity (www.konaequity.com); and
ZoomInfo Technologies LLC (www.zoominfo.com).
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5. Projected Reporting, Recordkeeping, and Other Compliance
Requirements

AD costs per airplane are 1 work hour plus $85 reporting costs for
initial inspection, for a total of $170. The AD cost per small entity
is shown in the ``Cost'' column of Table 1 and cost impact is measured
by AD cost as a percentage of revenues. As the table shows, the mean
cost impact is 0.1% of annual revenues, with a maximum impact of 0.46%
of annual revenues, and a minimum impact below 0.01%.

(ILLUSTRATION) Table 1 - Cost Impact on Small Entities

Costs under 1% of revenues for all of the small entities lead the
FAA to conclude that this rule does not have a significant impact on a
substantial number of small entities.

6. Significant Alternatives Considered

As part of the FRFA, the FAA is required to consider regulatory
alternatives that may be less burdensome.
The FAA did not find any significant regulatory alternatives to
this AD that would still accomplish the safety objectives of this AD.

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, and
(2) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the RFA.

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: