AIRWORTHINESS DIRECTIVE On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CL-600/119 and issues the following 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. Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes AD/CL-600/119 Amdt 1 Power Control Unit Rod Centering Mechanism 11/2009 DM Applicability: Bombardier Inc. Models: CL-600-2C10, serial numbers 10003 to 10259. CL-600-2D15 and CL-600-2D24, serial numbers 15001 to 15099. Requirement: Install the new Elevator Power Control Unit (PCU) centering mechanism in accordance with Accomplishment Instructions in Part 2 of Bombardier Aerospace Service Bulletin 670BA-27-042, Revision B, dated 2 June 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada. Incorporation of Bombardier Aerospace Service Bulletin 670BA-27-042, Original Issue, dated 14 October 2008, or Revision A, dated 8 January 2009, meets the intent of this AD only if Bombardier Aerospace Repair Engineering Order (REO) 670-27-31-001, or Service Non-Incorporated Engineering Order (SNIEO) S01 or S02 from kit drawing KBA670-93702 is also incorporated at the same time. Note: Transport Canada AD CF-2009-28R1 dated 14 August 2009 refers. Compliance: Within 6,000 flight hours after the effective date of this AD. This Amendment becomes effective on 24 September 2009. Background: During a PCU Centering Functional Check on two CL-600-2C10 aircraft, sustained oscillations were discovered when a control rod was disconnected. These sustained oscillations could render the elevator surface inoperable and cause subsequent loss of pitch control of the aircraft. This AD mandates incorporation of a new centering mechanism on the elevator torque tube to prevent these sustained oscillations. This amendment corrects date of Revision B of the referenced SB. The original issue of this AD becomes effective 24 September 2009. James Coyne Delegate of the Civil Aviation Safety Authority 2 September 2009