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 39.001(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. Auxiliary Power Units AD/APU/21 RE220 Fuel Nozzles 8/2007 Applicability: Honeywell International Inc. model RE220 (RJ) Auxiliary Power Units (APUs) Part Number (P/N) WE3800770-2. Note 1: These APUs are installed in but not limited to Bombardier model CL-600-2C10 aeroplanes. Requirement: 1. Replace APU fuel nozzles, P/N WE3830486-2, with new design fuel nozzles, P/N WE3830513-l. Information on fuel nozzle replacement can be found in Honeywell International Inc. alert service bulletin (ASB) RE220-49-A7714, dated 4 November 2002. 2. Re-identify the APU as follows: a. Change the P/N from WE3800770-2 to WE3800770-3 on the identification plate, by removing the -2 and vibropeening or hand stamping a -3 in its place. b. Vibropeen or hand stamp the letter "C" after the serial number to show conversion. c. Vibropeen or hand stamp "Change Number 3" on the identification plate adjacent to the MOD RECORD. 3. Start the APU and perform a visual fuel leak check after one minute of operation. 4. Do not install fuel nozzles P/N WE3830486-2 into any APU P/N WE3800770-3. Note 2: FAA AD 2003-15-07 Amdt 39-13250 dated 24 July 2004 refers. Compliance: 1, 2 and 3. Within 30 days after the effective date of this AD, unless previously accomplished. 4. From the effective date of this AD. This Airworthiness Directive becomes effective on 2 August 2007. Background: This AD requires replacing the existing fuel nozzles with new design fuel nozzles, making re-identification updates to the APU identification plate, and operating the APU to perform a visual inspection for fuel leaks. This amendment is prompted by reports of cracks occurring in the existing APU fuel nozzles leading to fuel leaks. The actions specified by the AD are intended to prevent APU compartment fires and fuel vapour explosion. David Punshon Delegate of the Civil Aviation Safety Authority 19 June 2007