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 39.1 (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 Canada Turbine Engines - JT15D Series AD/JT15D/9 Borescope Inspection of Impeller Rear Face 10/2003 Applicability: Pratt and Whitney Canada (PWC) JT15D-1, JT15D-1A, and JT15D-1B engines which incorporate impeller Part Number (P/N) 3020365; and 1. Which were not previously inspected per Overhaul Manual Revision 14; or later revisions; or 2. Which have Serial Numbers (S/N) not listed in Table 1 of PWC Service Bulletin (S/B) 7590. Requirement: 1. Perform an inspection of the impeller in accordance with PWC S/B 7590 dated 23 May 2003. 2. Repair or replace impellers that do not meet the inspection requirements of PWC S/B7590 dated 23 May 2003, or later revisions. Note: Canadian AD CF-2003-17 refers. Compliance: For Requirement 1: At the next engine shop visit; or Within 250 flight cycles for engines that have impellers with a Total Cycles Since New (TCSN) equal to, or greater than, 5000 flight cycles, whichever occurs first. For Requirement 2: Prior to further flight following completion of Requirement 1 of this Directive. This Airworthiness Directive becomes effective on 2 October 2003. Pratt and Whitney Canada Turbine Engines - JT15D Series AD/JT15D/9 (continued) Background: Incidents of impeller fracture and uncontained liberation of high energy fragments have occurred. Machining marks on the rear face of the impeller were identified as the cause of these failures. This Directive requires a borescope inspection of the impeller. Jim Coyne Delegate of the Civil Aviation Safety Authority 19 August 2003 The above AD is notified in the Commonwealth of Australia Gazette on 10 September 2003.