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/BAe 146/73 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. British Aerospace BAe 146 Series Aeroplanes AD/BAe 146/73 Amdt 1 MLG Door Lock and MLG Uplock 11/2005 Applicability: All BAe 146 Series and Avro 146-RJ Series aircraft. Requirement: Action in accordance with British Aerospace Regional Aircraft Service Bulletin 32-150-70656A Revision 1. Note: UK CAA AD 005-12-98 refers. Compliance: As specified in the Requirement document. This Amendment becomes effective on 27 October 2005. Background: The manufacturer received a report of the roller assembly fitted to the main landing gear door lock breaking into segments. A roller assembly of the same type is fitted in the main landing gear uplock and cracks have been reported. Dowty Hydraulics have established that the cracks were initiated during manufacture. The modified rollers use a different manufacturing assembly process. Amendment 1 is issued to introduce the current issue of the Requirement document, and reference the related UK CAA AD. David Villiers Delegate of the Civil Aviation Safety Authority 15 September 2005