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 269/61 Fuel Tank Sump Cap Attachment - Inspection 12/77 Applicability: All models. Document: Hughes SIN No. N-148. Compliance: Within 100 hours time in service after 31 December 1977 and thereafter at intervals not exceeding 300 hours time in service.