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. Boeing 767 Series Aeroplanes AD/B767/235 ECS Duct Assembly Insulation 3/2008 Applicability: Model 767-200 and 767-300 series aircraft, as identified in Boeing Service Bulletin 767-21A0167 Revision 1, or later FAA approved revision; excluding variable number VK031. Requirement: Action in accordance with the technical requirements of FAA AD 2008-02-16 Amdt 39-15346. Compliance: As specified in the Requirement document, with a revised effective date of 13 March 2008. This Airworthiness Directive becomes effective on 13 March 2008. Background: The FAA received reports of duct assemblies in the environmental control system (ECS) with burned BMS 8-39 polyurethane foam insulation. Also a report received from the manufacturer that aircraft were assembled with duct assemblies in the ECS wrapped with BMS 8-39 polyurethane foam insulation, a material of which the fire retardant properties deteriorate with age. The actions of this Directive are intended to prevent a potential electrical arc from igniting the BMS 8-39 polyurethane foam insulation on the duct assemblies of the ECS. David Villiers Delegate of the Civil Aviation Safety Authority 1 February 2008