COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Lycoming Piston Engines AD/LYC/104 Crankshaft Drive Gear Bolts 12/99 Applicability: Textron Lycoming Model O-540-F1B5 engines as detailed by serial number in FAA Airworthiness Directive 99-03-05 and installed in, but not limited to, Robinson R44 helicopters. Note: Copies of FAA AD 99-03-05 are available from CASA. CASA contact position is the Airworthiness Directive Publishing Controller. Contact number is 131 757. Requirement: Replace crankshaft drive gear bolt part number (P/N) STD-2209. Compliance: Within 10 hours time in service from the effective date of this directive. This Airworthiness Directive becomes effective on 2 December 1999. Background: This directive has been issued to prevent failure of the crankshaft bolt resulting in an engine failure. The requirement follows advice of a manufacturing error in bolts supplied to the Robinson Helicopter Company.