COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Schweizer (Hughes) 269 Series Helicopters AD/HU 269/73 Main Gearbox Ring Gear - Inspection and Increase of Bolt Torque 9/82 Applicability: All models 269A, 269A-1, 269B, 269C fitted with main gear box assembly P/N 269A5175-7, -9, -11, -13, -15 or -17, except those gearboxes identified with a letter "W" adjacent to the serial number on the identification plate. Document: Hughes SIN N-181. FAA AD 82-15-01 refers. Compliance: Within 100 hours time in service after 30 September 1982. Background: We are advised that there have been several reports of looseness to the main gearbox ring gear attach bolts. The possible resulting fatigue failure to bolts or ring gear carrier could cause loss of rotor drive, or jamming of the main gearbox.