COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes AD/DHC-8/6 MLG Uplock Actuator 8/89 Applicability: Model DHC 8 serial number 3 and subsequent with MLG uplock actuator part numbers 10800-103, -105, -107, -109 and -111 installed, and which do not have modification 8/1098 incorporated. Requirement: 1. Unless previously accomplished, inspect/rectify the MLG uplock installation in accordance with De Havilland SB No. 8-32-79 Revision A. 2. Rework and re-identify all uplock actuators in accordance with De Havilland SB No. 8-32-79 Revision A. Note 1: Compliance with Requirement 2 constitutes terminating action for Requirement 1. Note 2: Canadian AD CF-89-03 refers. Compliance: 1. Within 50 hours time in service after 10 August 1989; repeat, prior to further flight, whenever the proximity sensor and/or proximity sensor mounting bracket on an uplock actuator has been reset or replaced. 2. Prior to 28 February 1990. Background: A trapped MLG uplock actuator target lever may occur under adverse tolerance conditions combined with a failed target lever return spring. This occurrence will prevent the rotation of the main gear uplock latch and the release of the main landing gear.