COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Rolls Royce Turbine Engines - Spey Series AD/RRT-S/11 Steel Turbine Discs 13/92 Applicability: Spey series engines as detailed in Rolls Royce Service Bulletin Sp72-1044. Requirement: Action in accordance with the requirements of Rolls Royce Service Bulletin Sp 72-1044. Compliance: Effective 10 December 1992: At next engine shop visit during which, either a low pressure turbine or a high pressure turbine overhaul is scheduled. Background: This Directive requires steel turbine discs which have completed at least 40% of their published service life, to be inspected in accordance with the overhaul manual. The requirement addresses concern with evidence of low cycle fatigue cracks originating from corrosion pits in a number of Spey steel turbine discs.