AIRWORTHINESS DIRECTIVE On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/JT8D/42 and issues the following 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. Pratt and Whitney Turbine Engines - JT8D Series AD/JT8D/42 Amdt 1 8th Stage High Pressure Compressor Discs. 13/2006 DM Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R and -17AR turbofan engines, with 8th stage high pressure compressor (HPC) front hubs as listed in Table 1 of FAA AD 2006-17-07R1. Requirement: Action in accordance with FAA AD 2006-17-07R1 with a revised effective date of 26 October 2006. Compliance: As detailed in FAA AD 2006-17-07R1 with a revised effective date of 26 October 2006. Any engine with a HPC front hub that has been inspected in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07) counts as an inspection towards compliance with this AD. This Amendment becomes effective on 26 October 2006. Background: This AD requires either replacing HPC front hubs and HPC disks that have operated at any time with PWA 110-21 coating and that operated in certain engine models, or, visually inspecting and FMPI for cracking of those parts and re-plating them if they pass inspection. This AD results from an investigation by PW, which concluded that any HPC front hub or HPC disk coated with PWA 110-21 that ever operated on JT8D-15, -15A, -17, -17A, -17R, -17AR, -209, -217, -217A, -217C, and -219 turbofan engines, could crack before reaching their published life limit. This AD requires the same actions, but makes necessary corrections to inadvertent reference errors and omissions found in FAA AD 2006-17-07, and relaxes some of the compliance times in Table 5. The original issue of this AD became effective 26 October 2006. James Coyne Delegate of the Civil Aviation Safety Authority 23 October 2006