Airworthiness Directive · Amendment 39-21839 · Wing structure
Viking Aircraft Limited Airplanes
This AD applies to Viking Air Limited Model DHC-3 airplanes, all serial numbers, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Viking Air Limited 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 identifies the unsafe condition as fatigue damage of the wing strut lug fitting components and the fuselage to wing strut attachment (tie-bar). This AD requires 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 issuing this AD to address the unsafe condition on these products.
Unless already done, do the following actions in paragraphs (f)(1) through (3) of this AD:
(1) For all airplanes: Within 3 months after the effective date of this AD, determine and record the number of equivalent air time hours on each wing and tie-bar by doubling the total hours time-in-service (TIS) accumulated on each part. If the total hours TIS of a tie-bar is unknown or cannot be determined, use the total hours TIS of the wing strut lug fitting on the main spar.
(2) For airplanes with a maximum certificated gross weight that has never exceeded 8,000 pounds: Remove from service each left-hand and right-hand wing strut fitting and tie-bar by following the Accomplishment Instructions in Viking DHC-3 Otter SB V3/0008, Revision NC, dated February 9, 2017, and the Replacement section of the Accomplishment instructions in De Havilland Aircraft of Canada, Limited DHC-3 Otter Service Bulletin Number 3/37, Revision B, dated October 8, 1982, at whichever of the following compliance times that occurs later:
(i) Before the part accumulates 40,000 equivalent air time hours, or
(ii) Within 12 months after the effective date of this AD.
(3) For airplanes with a maximum certificated gross weight that has ever exceeded 8,000 pounds: Remove from service each left-hand and right-hand wing strut fitting and tie-bar by following the Accomplishment Instructions in Viking DHC-3 Otter SB V3/0008, Revision NC, dated February 9, 2017, and the Replacement section of the Accomplishment instructions in De Havilland Aircraft of Canada, Limited DHC-3 Otter Service Bulletin Number 3/37, Revision B, dated October 8, 1982, at whichever of the following compliance times that occurs later:
(i) Before the part accumulates 32,200 equivalent air time hours, or
(ii) Within 12 months after the effective date of this AD.
