AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CL-600/32 Amdt 1 and issues the following 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. Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes AD/CL-600/32 Amdt 2 Underfloor Pressure Bulkhead at FS409.00 7/2002 Applicability: Models Serial Numbers CL-600-1A11 (CL-600) 1004 through 1085 CL-600-2A12 (CL-601) 3001 through 3066 CL-600-2B16 (CL-601-3A/-3R) 5001 through 5194 CL-600-2B16 (CL-604) 5301 through 5352 Requirement: Perform a detailed visual inspection of both the fuselage frame FS409 bulkhead web (P/N 600-32014-71/-95/-105/-137, as applicable) from the corner radius at WL 49.00, LBL 6.00 and RBL 6.00, and the angles (P/Ns 600-32014-13 and -15, or -113 and - 115, as applicable) between LBL 9.0 and RBL 9.0. The inspection is to be carried out in accordance with Part 2, Accomplishment Instructions, of Bombardier Service Bulletins 600-0679, 601-0501, or 604-53-007, as applicable. Note: Transport Canada AD CF-1997-16R2 refers. Compliance: 1. Unless the initial inspection is already accomplished: 1. CL-600-1A11 aircraft. (i) For aircraft with 1900 or more flight cycles, initially within 100 flight cycles after 5 November 1997; and, (ii) For aircraft with less than 1900 flight cycles, not later than 2000 flight cycles since new. b. CL-600-2A12 and CL-600-2B16 aircraft. (i) For aircraft with 1100 or more flight cycles, initially within 100 flight cycles after 5 November 1997; and. (ii) For aircraft with less than 1100 flight cycles, not later than 1200 flight cycles since new. Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes AD/CL-600/32 Amdt 2 (Continued) Aircraft that are visually determined to be crack free are to be re-inspected at intervals not to exceed 600 flight cycles; until modified in accordance with Bombardier Service Bulletins 600-0680, 601-0503, or 604-53-006, as applicable. 2. Aircraft that are visually determined to have cracks that do not extend up to the angles as specified in the Requirement, may only be returned to service under the following conditions: 1. No more than one crack exists at each corner; and, b. Angles on the aft side of the web are visually confirmed to be crack free; and, c. No crack extends under the angles; and, d. Aircraft shall be re- inspected at intervals not exceeding 100 flight cycles; and, e. The cracked bulkhead is to be repaired before the aircraft accumulates 600 flight cycles or within 12 months, whichever occurs first, after the date of initial detection of the crack. The compliance times remain unchanged by this issue. This amendment becomes effective on 11 July 2002. Background: A check of 105 Challenger aircraft has revealed 13 aircraft with fatigue cracks in the pressure bulkhead frame at the forward end of the wing box cutout. Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes AD/CL-600/32 Amdt 2 (Continued) Amendment 1 deleted a specific repair date. Amendment 2 is issued in response to a revision of the related Transport Canada AD, which introduces a modification that provides terminating action for the repeat inspection requirements for those aircraft that have never developed cracks. Amendment 1 of this Airworthiness Directive became effective on 3 December 1998. The original issue of this Airworthiness Directive became effective on 5 November 1997. David Alan Villiers Delegate of the Civil Aviation Safety Authority 30 May 2002 The above AD is notified in the Commonwealth of Australia Gazette on 19 June 2002.