COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron 212 Series Helicopters AD/BELL 212/49 Tail Rotor Driveshaft Hangar Bearings 1/92 DM Applicability: All models fitted with tail rotor driveshaft bearings. P/N 204-040-623-003 with a S/N prefix of either "T" or "N" prior to N4000 and all - 005 bearings with a S/N prefix of either "T" or "N". Requirement: Action in accordance with Bell Alert Service Bulletin 212-91-69 Revision A. Note: FAA Priority Letter AD 91-24-16 refers. Compliance: Daily before first flight of the day after 27 November 1991. Background: A daily inspection of the tail rotor driveshaft bearings has been found necessary following a fatal accident which revealed the possibility of a production batch problem with these bearings.