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 EMB-135 and EMB-145 Series Aeroplanes AD/EMB-145/12 APU Firewall - 2 8/2008 Applicability: Models EMB-145 and EMB-135 aircraft, serial numbers 145462, 145484, 145495, 145505, 145528, 145540, 145549, 145555, 145590, 145625, 145637, 145642 through 145646, 145649, 145650, 145654, 145655, 145657 through 145660, 145662, 145664, 145666, 145672, 145674, 145675, 145677, 145681, 145683, 145684, 145688 through 145690, 145683, and 145697. Requirement: Accomplish a detailed visual inspection of the APU firewall for cracks and structural integrity. If cracking is detected during any inspection, before further flight, repair in accordance with the limits and instructions of the applicable Structural Repair Manual (SRM); or, Replace the part number 145-47494-401 firewall with a part number 145-47494-607 firewall in accordance with Part II of EMBRAER Service Bulletin (SB) No. 145-53-0037 or SB No. 145LEG-53-0010, as applicable; or later CTA/ANAC approved revision. Note: Brazil CTA AD 2003-07-02 Amdt 39-999 refers. Compliance: Inspect within 200 flight hours after 31 July 2008, and thereafter at intervals not to exceed 200 flight hours or 90 days, whichever occurs first; until replacement of the part number 145-47494-401 firewall with a part number 145-47494-607 firewall. This Airworthiness Directive becomes effective on 31 July 2008. Background: Reports were received of cracking of the APU firewall. Undetected cracking could affect the structural integrity and sealing function of the firewall. David Villiers Delegate of the Civil Aviation Safety Authority 18 June 2008