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-76/19 Main Rotor Blade - Tip Plate Assembly Retention Bolts - Inspection and Replacement 6/81 Applicability: All models. Document: Sikorsky Alert SB 76-65-23. Compliance: As per requirement document. Background: The manufacturer has advised the loss of a main rotor blade tip cap in flight.