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. Embraer ERJ-170 Series Aeroplanes AD/ERJ-170/24 Wing Stub Rear Box Vapour Barrier Assembly 10/2009 Applicability: Model ERJ 170-100 STD, -100 LR, -100 SU, -100 SE, -200 STD, -200 SU and -200 LR aircraft, serial numbers 17000002, 17000004 through 17000013 and 17000015 through 17000235. Requirement: Action in accordance with the requirements of ANAC AD 2009-07-01 Amdt 39-1274. Note: Embraer Service Bulletin No.170-57-0036 original issue, or later ANAC approved revision, refers. Compliance: As specified in the Requirement document, with a revised effective date of 24 September 2009. This Airworthiness Directive becomes effective on 24 September 2009. Background: The manufacturer has determined that there could be missing sealant on the vapour barrier assembly in the wing stub (centre section) rear box. In the event of fuel tank leakage in the area of the wing stub rear box, and an associated inadequately sealed vapour barrier assembly, the migration of flammable vapours and fluids to the middle electronic bay could occur. In the presence of an ignition source this situation could lead to an uncontained fire. David Villiers Delegate of the Civil Aviation Safety Authority 12 August 2009