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-8/111 Fuselage Bottom Skin and VHF 3/2006 Antenna Support Structure Applicability: Models DHC-8-401 and DHC-8-402 aircraft, serial numbers 4003 through 4076, and 4078 through 4081. Requirement: Action in accordance with Transport Canada AD CF-2003-28. 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: The manufacturer received a report of an aircraft with an 8-inch crack on the fuselage skin in the vicinity of the forward No. 2 VHF antenna. Investigation revealed that four of eight cleats, part number 85307891, attaching the internal antenna support plate, had cracked as well. Since the original report, other aircraft were found to have cracked cleats. If undetected, cracking in the fuselage skin could result in rapid decompression of the aircraft. David Villiers Delegate of the Civil Aviation Safety Authority 3 February 2006