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 747 Series Aeroplanes AD/B747/339 Fuselage Lower Lobe Skin 3/2006 STA 741 to STA 1741 Applicability: Model 747-400, -400D, and -400F series aircraft; as identified in Boeing Alert Service Bulletin 747-53A2505 original issue, or later FAA approved revision. Requirement: Action in accordance with the technical requirements of FAA AD 2005-25-26 Amdt 39-14419. 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 FAA received reports of skin corrosion in the cargo compartments of four Model 747 series aircraft that were delivered between 1995 and 1999. Such corrosion, unless detected and corrected, could penetrate the thickness of the skin and cause cracking, which could result in rapid decompression of the aircraft. David Punshon Delegate of the Civil Aviation Safety Authority 17 January 2006