COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron 412 Series Helicopters AD/BELL 412/36 Main Rotor Mast 5/95 Applicability: All model 412 series helicopters fitted with main rotor mast P/N 412-040-101-105, -109, -117, -121, -125, -127, -129 and spline plate P/N 412-010-167-101, -105 or 412-010-177-101, -105, -109, -113 or -117. Requirement: Action in accordance with Bell Alert Service Bulletin 412-94-81 Revision A. Compliance: Within 100 hours time in service from 27 April 1995 or by 27 August 1995, whichever occurs first. Background: The manufacturer has revised the procedures for determining the retirement life of the main rotor mast and spline plate for the 412 and 412SP, which now has a retirement life of 10,000 hours or 80,000 maximum Retirement Index Numbers (RIN), whichever occurs first. For the 412HP and 412EP the retirement life is 10,000 hours or 60,000 RIN, whichever occurs first.