Airworthiness Directive · Amendment 39-19460 · Wings
Viking Air Limited Airplanes
This AD applies to Viking Air Limited (Viking) Model DHC-3 airplanes with wing strut bolts part numbers (P/N) C3W114-3, C3W129-3, and C3W128-3 (Pre MOD 3/1010), all serial numbers, certificated in any category.
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.
Unless already done, do the following actions:
(1) Within 12 months after November 28, 2018 (the effective date of this AD), inspect the wing strut attach bolts installed on the airplane for pitting on the shank by following paragraph A of the Accomplishment Instructions in Viking DHC-3 Otter Service Bulletin Number: V3/0006, Revision C, dated May 16, 2018 (Viking SB V3/0006, Revision C).
(2) If pitting is found during the inspection required in paragraph (f)(1) of this AD, before further flight, replace the defective bolt with either a post MOD 3/1010 wing strut bolt (P/Ns C3W114-5, C3W128-5, and C3W129-5; or C3W114-9, C3W128-9, and C3W129-9) or a new or serviceable pre MOD 3/1010 wing strut bolt that has been inspected by following paragraph A of the Accomplishment Instructions in Viking SB V3/0006, Revision C.
(3) After November 28, 2018 (the effective date of this AD), you may continue to use pre MOD 3/1010 bolts provided these bolts are inspected for pitting immediately before installation by following paragraph A of the Accomplishment Instructions in Viking SB V3/0006, Revision C, and you document the inspection in the airplane maintenance records.
This AD allows credit for the actions required in paragraph (f)(1) or (2) of this AD if done before November 28, 2018 (the effective date of this AD) by following Viking Service Bulletin DHC-3 Otter V3/0006 Revision NC, A, or B.
