AD/DHC-8/115 - Main Landing Gear Proximity Sensors (Cth)

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.

Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes AD/DHC-8/115 Main Landing Gear Proximity Sensors 4/2006

Applicability: DHC-8 aircraft, Models 400, 401 and 402, serial numbers 4001 to 4055. Requirement: If not previously accomplished replace the L/H and R/H main landing gear downlock proximity sensors with improved version by incorporating retrofit ModSum 4-113331. Bombardier Service Bulletin 84-32-09 dated 18 May 2001, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating ModSum 4-113331. Note 1: Aircraft that were fitted with improved sensors during production via Modsum 4-113330 are not affected by this Directive. Note 2: Transport Canada AD CF-2001-16R1 refers. Compliance: Within 30 days after the effective date of this Directive. This Airworthiness Directive becomes effective on 13 April 2006. Background: Transport Canada has advised that due to manufacturing process problems combined with higher than qualified acceleration levels experienced by the main landing gear downlock proximity sensors, these sensors may fail concurrently on the same gear in the NEAR position. This failure could potentially inhibit the affected gear from extending. The indication to the flight crew from these failures is misleading.