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/B747/397 Fuselage Section 41 Frames 12/2009 Applicability: Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, 747SR and 747SP series aircraft, as identified in Boeing Alert Service Bulletin 747-53A2732 original issue, or later FAA approved revision. Model 747-400, -400D and -400F series aircraft, as identified in Boeing Alert Service Bulletin 747-53A2753 original issue, or later FAA approved revision. Requirement: Action in accordance with the technical requirements of FAA AD 2009-19-05 Amdt 39-16022. Compliance: As specified in the Requirement document, with a revised effective date of 19 November 2009. This Airworthiness Directive becomes effective on 19 November 2009. Background: The FAA received reports of cracking in fuselage frames made of 2024 aluminium alloy that were installed during previous modification of the frames in Section 41 and during production. Such cracking, unless detected and corrected, could result in cracking of the adjacent fuselage skin and consequent rapid decompression of the aircraft. David Villiers Delegate of the Civil Aviation Safety Authority 30 September 2009