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 412/37 Internal Hoist 8/95 Applicability: All Bell Helicopter Textron 412 Series Helicopters with an internal hoist, P/N 214- 070-300-001/-101, installed on the right hand side. Requirement: 1. For each hoist operation, performed within the c.g. penalty region of Fig 1 of Bell Alert Service Bulletin (ASB) 412-95-83, log an additional four hours time in service against the main rotor yoke, mast and lower cone seat. 2. For hoist operations performed before 20 July 1995, log additional hours against the main rotor yoke, mast and lower cone seat in accordance with Bell ASB 412- 95-83. 3. Retire from service each main rotor yoke, mast and lower cone seat where the retirement life has been exceeded as a result of this calculation. Compliance: 1. Before the first flight after 20 July 1995. 2. Before 25 hours time in service or before 20 August 1995, whichever occurs first. 3. Within 150 hours time in service after completion of Requirement 2. Background: Flight testing and fatigue analysis has shown that higher than expected loads are experienced on the main rotor yoke, mast and lower cone seat when operating the hoist with the aircraft c.g. within a certain region. A revised method of calculating the retirement lives for such operations is instituted.