COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters AD/BELL 206/135 Main Rotor Trunnion and Mast 10/95 Applicability: All Bell 206L, 206L-1, 206L-3 and 206L-4 helicopters fitted with main rotor trunnion P/N 206-011-120-103 and mast P/N 206-040-535-001/-005/-101 /-105. Note: Main rotor trunnion P/N 206-011-120-001 is no longer permitted to remain in service. Requirement: Retire the main rotor trunnion before it has attained a Retirement Index Number (RIN) of 24 000 as adjusted in Bell ASB 206L-94-99, Revision A, Table 3. Retire the mast before it has attained a RIN of 44 000 as adjusted in Table 4, or before the time in service as adjusted in Table 2 of Bell ASB 206L-94-99, Revision A, whichever occurs first. Compliance: Before 100 hours time in service after 14 September 1995 but no later than 17 December 1995. Background: Bell Helicopter's fatigue testing and analysis have shown that the life of certain critical components can be estimated in a more accurate manner when the calculations are based on changes in power. The fatigue life is no longer to be based on component hours but on the number of power change events. A history card for each component will have to be created to document the Retirement Index Number.