1AD/DHC-6/50 - Main Landing Gear Legs - Inspection

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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DHC-6 (Twin Otter) Series Aeroplanes

AD/DHC-6/50 Main Landing Gear Legs - Inspection 5/80

Applicability: All model DHC-6 which do not have De Havilland Aircraft of Canada Ltd.

Modification 6/1660 incorporated.

Requirement: 1. Inspect as necessary the main landing gear legs in accordance with either Schedule No. 1 or Schedule No. 2 of the De Havilland Aircraft of Canada Ltd. SB No.

6/380. In lieu of the visual external inspections required by paragraph (a) of Schedule No. 1 or Schedule No. 2, refer to the Accomplishment Instructions and Figure 1 of the referenced Service Bulletin, remove the external finish from the Inspection Area and inspect using a dye penetrant method. If no cracks are observed, reprotect the stripped area, and proceed in accordance with paragraph (b) of the appropriate Schedule. If cracks are found, proceed in accordance with Schedule No. 1 paragraph (e), (f) and (g) as appropriate.

2. Perform a Check D inspection in accordance with the Accomplishment Instructions of the De Havilland Aircraft of Canada Ltd. SB No. 6/380.

Note: Transport Canada Airworthiness Directive CF-80-06 De Havilland refers.

Compliance: Para. 1 - Within 50 hours time in service after 15 May 1980, unless already accomplished.

Para. 2 - Within 2400 hours flight time or before 21 December 1980 whichever comes first, unless already accomplished within the last 9600 hours flight time or 4 years, and thereafter at intervals not to exceed 12000 hours flight time or 5 years whichever comes first.

Background: Advice from overseas indicated failures of the Main Landing Gear Legs originated from corrosion pockets in the Y-joint weld.