COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DHC-6 (Twin Otter) Series Aeroplanes AD/DHC-6/49 Amdt 3 Applicability: Model DHC-6 series. Flight Control Rods 2/93 Requirement: Action in accordance with the technical requirements of Transport Canada AD CF-80-03R3. Note: De Havilland SB 6/390 Revision A and SB 6/502 refer. Compliance: As specified in the Requirement Document with a revised effective date of 3 February 1992 for Australian registered aircraft. The compliance of the previous issue of this Directive remains unchanged. This Amendment is effective from 4 February 1993. Background: The flight control rods have been the subject of a series of special inspections, modifications, and replacements to prevent longitudinal stress corrosion cracking. Amendment 2 mandated the replacement of 2024-T3 alloy flight control rods and provided an increase in the inspection interval of 6061-T6 control rods pursuant to Canada's Aging Aircraft program. Amendment 3 is issued in response to a revision of the relevant Country of Origin AD, which extends the deadline for removal of the 2024-T3 rods because of lack of replacements, subject to the alternative of inspecting the rods during this extension.