AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. Rolls Royce Turbine Engines - RB211 Series AD/RB211/38 Engine - High Pressure Turbine Disc 12/2008 Applicability: Rolls-Royce plc RB211-524, RB211-535C and RB211-535E4 series engines that have High Pressure (HP) Turbine Discs installed, identified by part and serial number in Rolls-Royce Alert Non-Modification Service Bulletin (NMSB) 72-AF996 Revision 1 dated 17 July 2008. Note 1: These engines are known to be installed on, but not limited to, Lockheed Martin L-1011 aircraft, Boeing 747, 757 and 767 series aircraft, and Tupolev Tu204 aircraft. Requirement: 1. Remove from aircraft HP turbine discs identified in Rolls-Royce Alert NMSB 72-AF996 Revision 1 and replace with a serviceable disc. Prior to reinstallation on an engine, inspect each HP turbine disc in accordance with the instructions of the SB. 2. HP turbine discs that do not pass the inspection as detailed in Requirement 1 of this AD shall not be reinstalled on an engine and must be returned to Rolls-Royce for further investigation. 3. Do not install any HP turbine disc identified in Rolls-Royce Alert NMSB 72-AF996 Revision 1 on any engine; unless it has been inspected in accordance with the instructions of Rolls-Royce Alert NMSB 72-AF996 Revision 1 and has passed that inspection. Note 2: EASA AD 2008-0176 dated 18 September 2008 refers. Compliance: For Requirement 1 - After the effective date of this AD, within the applicable time period indicated in Section 1.C "Compliance" of Rolls-Royce Alert Non-Modification Service Bulletin 72-AF996 Revision 1. For Requirements 2 and 3 - From the effective date of this AD. This Airworthiness Directive becomes effective on 20 November 2008. Background: Rolls-Royce has recently discovered that there may be cracks present in certain HP turbine discs, due to a possible error in an eddy current inspection technique carried out during maintenance. The affected part and serial numbers are identified in Rolls-Royce Alert Non-Modification Service Bulletin 72-AF996 Revision 1 (the SB). This condition, if not corrected, may lead to disc failure and subsequent high-energy debris release. This AD requires the removal from service of the affected HP turbine discs and inspection thereof, prior to reinstallation. Charles Lenarcic Delegate of the Civil Aviation Safety Authority 3 October 2008