COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Rolls Royce Turbine Engines - Dart Series AD/DART/6 Amdt 1 Reduction Gear 5/98 Applicability: All Dart series engines listed in Part 1A of Rolls Royce Service Bulletin Da72-348 Revision 12 dated November 1997. Requirement: Modify the Reduction Gear Assembly in accordance with Rolls Royce Service Bulletin Da72-348 Revision 12 dated November 1997. Note 1: Rolls Royce Service Bulletin Da72-348 Revision 12 dated November 1997 is re-issued to re-classify the Modification as Mandatory and extend the applicability. Note 2: CAA AD 1935 also refers. Compliance: As specified in Rolls Royce Service Bulletin Da72-348 Revision 12 dated November 1997. This amendment becomes effective on 23 April 1998. Background: The manufacturer has advised that a failed annulus gear resulted in the malfunctioning of an engine in service. Manual feathering was initiated but the propeller failed to feather, decoupling of the propeller occurred, followed by over speeding of the propeller to bursting point causing extensive damage to the adjacent engine and the aircraft fuselage. The original issue of this airworthiness directive became effective on 31 October 1987.