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 CAR 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. Allison Turbine Engines - 250 Series AD/AL 250/81 Third Stage Turbine Wheels 6/2002 Applicability: Allison 250 - C28 Engines with third stage turbine wheels Part Number (P/N) 6899383 and with Serial Numbers (S/N) listed in Table 1 of this Directive. Requirement: Remove from service all turbine wheels P/N 6899383 listed by S/N in Table 1 of this Directive. Note: FAA AD 2002-06-08 refers. Compliance: Effective 13 June 2002; as per Table 2 of this Directive. This Airworthiness Directive becomes effective on 13 June 2002. Background: Fractures of the third stage turbine blade tips and shrouds could cause uncommanded shutdowns. New lower life limits have been established to address this problem. This Directive requires the removal from service of certain turbine wheels that exceed the new lower life limits. Table 1. S/N's of Affected Third Stage Turbine Wheels HX91428R HX91489R HX91707R HX91456R HX91490R HX91708R HX91457R HX91492R HX91709R HX91428R HX91489R HX91707R HX91456R HX91490R HX91708R HX91457R HX91492R HX91709R HX91458R HX91493R HX91710R HX91459R HX91494R HX91711R HX91461R HX91500R HX91712R HX91462R HX91501R HX91713R HX91464R HX91503R HX91714R HX914659 HX91504R HX91715R HX91465R HX91506R HX91721R HX91466R HX91507R HX91722R HX91467R HX91508R HX91726R HX91468R HX91510R HX91733R HX91469R HX91511R HX91735R HX91471R HX91512R HX91736R HX91472R HX91513R HX91738R HX91473R HX91519R HX91742R HX91474R HX91520R HX91744R HX91475R HX91522R HX91748R HX91477R HX91523R HX91749R HX91478R HX91524R HX91750R HX91480R HX91525R HX91754R HX91482R HX91526R HX91764R HX91483R HX91527R HX91765R HX91485R HX91528R HX91766R HX91486R HX91529R HX91767R HX91487R HX91530R HX91768R HX91488R HX91706R HX91769R Table 2. Removal Schedule As of the effective date of this AD Remove by (1) With fewer than 2,800 cycles-since- new (CSN), and fewer than 1,400 hours' time-since-new (TSN). 3,000 CSN or 1,500 hours TSN, whichever occurs earlier. (2) With between 2,800 and 3,000 CSN (inclusive), and fewer than 1,500 hours TSN. 200 additional cycles or 100 additional hours, after the effective date of this AD, whichever occurs earlier. (3) With fewer than 3,000 CSN, and between 1,500 and 3,000 hours TSN. 100 additional hours, after the effective date of this AD. (4) With between 3,000 and 6,000 CSN (inclusive), and fewer than 1,500 hours TSN. 200 additional cycles, after the effective date of this AD. (5) With between 3,000 and 6,000 CSN and between 1,500 and 3,000 hours TSN. 200 additional cycles or 100 additional hours, after the effective date of this AD, whichever occurs earlier. (6) With more than 6,000 CSN, or more than 3,000 hours TSN Before further flight. James Coyne Delegate of the Civil Aviation Safety Authority 15 April 2002 The above AD is notified in the Commonwealth of Australia Gazette on 22 May 2002.