COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters AD/HU 369/17 Tail Rotor Drive System - Inspection 6/75 Applicability: All models equipped with metal tail rotor blades and all models with drive shafts not previously indexed. Document: Hughes SIN No. HN-86. Compliance: For Part 1 - Within 100 hours time in service after 30 June 1975. For Part 2 - At intervals not exceeding 100 hours time in service after 30 June 1975.