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 206/77 Tail Rotor Drive Shaft - Replacement of Bearing Hangars 12/78 Applicability: Models 206A, 206B, AB206 & AB206B with S/Nos. as per Requirement Doc's. Document: 1. Bell SB No. 206-77-9; or 2. FAA AD 78-16-01 Amendment 39-3271; or 3. Agusta SB No. BT206-123. Compliance: No later than the next scheduled 1200 hourly inspection completed after 31 January 1979. Background: AD/Agusta 206/61 equivalent.