COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Sikorsky S-76 Series Helicopters AD/S-76/27 Main Rotor Blade Spar Tip End - Inspection 5/83 Applicability: All models with main rotor blade assemblies P/N 76150-09000 and P/N 76150- 09100-041 thru -050, unless the blade assemblies are marked as RS-004E-II or RS- 004F-II. Document: Sikorsky Alert Service Bulletin No. 76-65-34. Compliance: Within 100 hours time in service after 31 May 1983 and thereafter at each scheduled tip cap removal. Background: Cracks were detected at the spar tip end in one blade undergoing repair at Sikorsky Aircraft.