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. British Aerospace BAe 146 Series Aeroplanes AD/BAe 146/129 Undercarriage Main Beam 13/2007 Sidestay Bolts at Frame 29 Applicability: All Model BAe 146 and AVRO 146-RJ series aircraft, all serial numbers. Requirement: Action in accordance with the requirements of EASA AD 2007-0277. Note: BAE Systems (Operations) Inspection Service Bulletin ISB 53-194 original issue, or later EASA approved revision, refers. Compliance: As specified in the Requirement document, with a revised effective date of 20 December 2007. This Airworthiness Directive becomes effective on 20 December 2007. Background: During inspection of undercarriage main beam sidestays, bolts attaching the undercarriage main beam sidestay to frame 29 were found with sheared bolt heads. Undetected sheared or loose bolts could result in the possible collapse of a main landing gear. David Villiers Delegate of the Civil Aviation Safety Authority 8 November 2007