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 369/2 Amdt 1 Tail Rotor Gearbox - Inspection and/or Replacement 6/70 Applicability: All models fitted with tail rotor gearbox P/N 369A5400 with gearbox S/Nos. listed in Hughes SIN No. HN-1.1 and Addendum. Document: Hughes SIN No. HN-1.1 and addendum XI. Compliance: Before achieving 90 hours component total time in service, after 1 September 1971.