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-8/109 Fuel Access Panel Attachment Anchor Nut 3/2006 Applicability: Model DHC-8-400, DHC-8-401, and DHC-8-402 aircraft, serial numbers 4001, and 4003 through 4115. Requirement: Action in accordance with the requirements of Transport Canada AF CF-2005-08R1. Note: Bombardier Service Bulletins 84-57-10 Revision C, 84-57-11 Revision B, and 84-57-12 Revision B, or later Transport Canada approved revisions, refer. Compliance: As specified in the Requirement document, with a revised effective date of 16 March 2006. This Airworthiness Directive becomes effective on 16 March 2006. Background: There have been a number of reported cases of corrosion of dome anchor nuts at the centre wing upper surface fuel access panel attachment locations during "C" checks. In some cases, anchor nut domes were severely corroded and perforated. This condition, not corrected, could result in arcing and ignition of fuel vapour in the centre wing fuel tank during a lightning strike; and consequent fuel tank explosion. David Villiers Delegate of the Civil Aviation Safety Authority 3 February 2006