DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0214; Project Identifier 2018-CE-064-AD]
Airworthiness Directives; Viking Aircraft Limited Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for all Viking Air Limited Model DHC-3 airplanes. This proposed 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 fatigue damage of the wing strut lug fitting
components and the fuselage to wing strut attachment (tie-bar). This
proposed AD would require determining service life limits for the wing
strut fitting on the main spar and for the tie-bar and following
instructions for removal and replacement of affected parts. 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 August
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow
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
Limited Technical Support, 1959 De Havilland Way, Sidney, British
Columbia, Canada, V8L 5V5; phone: (North America) (800) 663-8444; fax:
(250) 656-0673; email: firstname.lastname@example.org; website:
https://www.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 (816)
Examining the AD Docket
You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0214; 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, any comments
received, and other information. The street address for Docket
Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Aziz Ahmed, Aviation Safety Engineer,
New York ACO Branch, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; phone: (516) 287-7329; fax: (516) 794-5531; email:
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-2021-0214; Project Identifier
2018-CE-064-AD" 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 Aziz
Ahmed, Aviation Safety Engineer, New York ACO Branch, FAA, 1600 Stewart
Avenue, Suite 410, 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.
Transport Canada, which is the aviation authority for Canada, has
issued AD Number CF-2017-29, dated August 24, 2017 (referred to after
this as "the MCAI"), to correct an unsafe condition for Viking Air
Limited Model DHC-3 airplanes. The MCAI states:
It has been determined that the current maintenance program does
not adequately address potential fatigue damage of the wing strut
lug fitting components or the fuselage to wing strut attachment (Tie
Bar). Affected parts must be replaced before specified air time
limits are reached to avoid fatigue cracking of the affected parts.
Cracking which is not detected may compromise the structural
integrity of the wing or the Tie-Bar.
Fatigue damage occurs more rapidly on aeroplanes that are
operated at higher gross weights. For that reason, the corrective
actions of this [Transport Canada] AD must be accomplished sooner
for aeroplanes that have been certified for operation at higher
Fatigue damage also occurs more rapidly on aeroplanes that are
operated below 2000 feet above ground level (AGL) over land due to
higher and more frequent gust and maneuvering loads. Low level
flights over water are not known to produce increased fatigue damage
on the DHC-3. For that reason, the corrective actions of this
[Transport Canada] AD must be accomplished sooner for aeroplanes
that have been operated at low altitudes over land.
This condition, if not addressed, could result in cracking and
failure of the structural integrity of the wing or the tie-bar.
You may examine the MCAI in the AD docket at https://www.regulations.gov
by searching for and locating Docket No. FAA-2020-0214.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Viking Air Limited DHC-3 Otter Service Bulletin
Number V3/0008, Revision NC, dated February 9, 2017. The service
information specifies determining service life limits for the wing
strut fitting on the main spar and for the tie-bar, and contains
instructions for removal and replacement. De Havilland Aircraft of
Canada has issued DHC-3 Otter Service Bulletin Number 3/37, Revision B,
dated October 8, 1982. The service information specifies instructions
for removal and replacement of the Fuselage to Wing Strut Attachment
Tie-Bar. 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.
This product has been approved by the aviation authority of another
country and is approved for operation in the United States. Pursuant to
our 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 on other products of the same type design.
Proposed AD Requirements in This NPRM
This AD requires accomplishing the actions specified in the service
information already described.
Differences Between This Proposed AD and the MCAI
The MCAI requires calculating the compliance time by using a
formula and estimating the altitudes at which an airplane has operated.
The MCAI also instructs operators to assume operations below 2,000 feet
AGL when the operating altitude of the airplane is unknown. Because the
FAA has no regulatory requirement for owners or operators to record or
maintain the operating altitude history of an aircraft, this proposed
AD would require calculating the compliance time by assuming all
operations occurred below 2,000 feel AGL.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 41 airplanes of U.S. registry.
The FAA also estimates that it would take about 300 work-hours per
airplane to replace both the wing strut fitting and the tie-bar. The
average labor rate is $85 per work-hour. Required parts would cost
about $5,599 per airplane.
Based on these figures, the FAA estimates the cost of the proposed
AD on U.S. operators to be $1,275,059 or $31,099 per airplane.
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.
The FAA determined that this proposed AD would not have federalism
implications under Executive Order 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
(1) Is not a "significant regulatory action" under Executive
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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
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.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness