AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CT7/10 Amdt 1 and issues the following 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. General Electric Turbine Engines - CT7 Series AD/CT7/10 Amdt 2 Propeller Gearbox(PGB) 7/2004 Applicability: General Electric Aircraft Engines (GEAE) CT7 series turboprop engines with propeller gearboxes (PGBs) identified by serial number (SN) in Table 1 of GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated 27 July 2001, and Table 1 of GEAE CT7 Turboprop Alert Service Bulletin (ASB) CT7-TP S/B 72-A0466 dated 17 April 2003. These engines are installed on, but not limited to, SAAB 340 series aeroplanes. Requirement: 1. Inspect the propeller gearbox (PGB) oil filter impending bypass button (IBB) for extension. If PGB oil filter IBB is extended, replace the oil filter and carry out inspections in accordance with 3.A of the Accomplishment Instructions contained in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0453,dated 27 July 2001. 2. Replace left and right-hand idler gears in accordance with the Accomplishment Instructions GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated 27 July 2001. 3. If the PGB is mated to a Hamilton Standard propeller and the left and right-hand idler gears have not been replaced in accordance with the Accomplishment Instructions contained in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452,dated 27 July 2001, replace the PGB. Note: FAA AD 2004-07-09 Amdt 39-13553 refers. Compliance: For Requirement 1: Unless previously accomplished, initial inspection within 50 hours time-in-service (TIS) after the effective date of this AD and thereafter on each day of aircraft operation until compliance with Requirment 2 or 3 of this Directive is achieved. For Requirement 2: At next workshop visit of the PGB after the effective date of this AD. For Requirement 3: Before accumulating an additional 2,000 engine flight hours after the 6 August 2003, the effective date of amendment 1 of this Directive. This Amendment becomes effective on 8 July 2004. General Electric Turbine Engines - CT7 Series AD/CT7/10 Amdt 2 (continued) Background: This AD is prompted by an on-going investigation that concluded that low-time PGB removals are due to accelerated wear of the PGB idler gears, rather than improperly hardened PGB input pinions. The actions specified in this AD are intended to prevent separation of the PGB left and right-hand idler gears, which could result in uncontained PGB failure and internal bulkhead damage, possibly prohibiting the auxiliary feathering system from fully feathering the propeller on certain PGB's. Amendment 1 clarified the applicability and, for administrative reasons, brought forward the effective date by one day. This amendment includes additional PGB and PGB gears as detailed in the reference documents. There are no changes to the inspection requirements. James Coyne Delegate of the Civil Aviation Safety Authority 28 May 2004 The above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.