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. General Electric Turbine Engines - CT7 Series AD/CT7/11 2nd Stage Turbine Aft Cooling Plates 11/2004 Applicability: General Electric Company (GE) CT7-2D1 turboshaft engines with 2nd stage turbine aft cooling plates, part number (P/N) 6064T07P02, and serial numbers (SN) starting with GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N installed. Asterisks represent any subsequent number or letter that follow the root SN. Note 1: These engines are installed on, but not limited to, Sikorsky S-70 helicopters. Requirement: 1. Replace any turbine stage 2 aft cooling plate, P/N 6064T07P02, with SNs starting with GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N, with a cooling plate that does not have a SN specified in this Directive. 2. Do not install stage 2 aft cooling plate, P/N 6064T07P02, SNs GFFN****, GFFP****, GFFR0*** through GFFR7***, GFFR81** through GFFR89**, GFFR8A** through GFFR8G**, GFFR8H92 through GFFR8H99, and GFFR8H9A through GFFR8H9N into any engine. Note 2: FAA AD 2004-16-07 Amdt 39-13763 refers. Note 3: GE CT7-TS Alert Service Bulletin 72-A0032, dated 11 June 2003, provides additional information regarding the disassembly of the gas generator turbine rotor assembly. Compliance: For Requirement 1: At the next disassembly of the gas generator turbine rotor assembly but not later than 5,000 cycles-since-new. For Requirement 2: After the effective date of this Directive. This Airworthiness Directive becomes effective on 28 October 2004. General Electric Turbine Engines - CT7 Series AD/CT7/11 (continued) Background: This Directive is in response to an uncontained failure of a turbine stage 2 aft cooling plate in a GE CT7 turboprop engine. The requirements of this Directive are to prevent a similar uncontained failure of 2nd stage turbine aft cooling plates in GE CT7-2D1 turboshaft engines. James Coyne Delegate of the Civil Aviation Safety Authority 14 September 2004 The above AD is notified in the Commonwealth of Australia Gazette on 6 October 2004.