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/DHC-19 Amdt 1 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. De Havilland DHC-1 (Chipmunk) Series Aeroplanes AD/DHC-1/19 Amdt 2 Flap Layshaft Operating Cam 12/2011 Applicability: English production (C1), all models, and Portuguese (T Mk 20) production models. Requirement: Inspect in accordance with British Aerospace Technical News Sheet (TNS) No.170 Issue 2, dated 1st December 1995. Note: TNS 170 superseded TNS 155. Compliance: At the next Check 4 inspection after the effective date of this AD; and thereafter at each subsequent Check 4 inspection. This Amendment becomes effective on 21 June 2011. Background: Reports were received of cracking or fracture of the brazing joint of the arm and associated tube, which together form the flap operating rod. Cracking of the operating cam has also been reported. Australia has had no Portuguese manufactured Chipmunks on the register, hence the CASA AD has only been effective for English production Chipmunks. This amendment is to include the Portuguese manufactured Chipmunk in the applicability for this AD, as a recent review indicates that this inspection is also applicable to the Portuguese model (T Mk 20). There is no change to the requirements or compliance. Amendment 1 was issued in August 1997 to include the current issue of the applicable Technical News Sheet. The original issue of this airworthiness directive became effective on 17 March 1969. Glen Steemson Delegate of the Civil Aviation Safety Authority 15 June 2011