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 737 Series Aeroplanes AD/B737/319 Body Buttock Line 0.07 Floor Beam 6/2008 Applicability: Model 737-300, -400, and -500 series aircraft, as identified in Boeing Service Bulletin 737-57-1210 Revision 2, or later FAA approved revision. Requirement: Action in accordance with the technical requirements of FAA AD 2008-04-21 Amdt 39-15393. Compliance: As specified in the Requirement document, with a revised effective date of 5 June 2008. This Airworthiness Directive becomes effective on 5 June 2008. Background: The FAA received reports of cracking in the BBL 0.07 floor beam. Undetected cracking could result in failure of the main deck floor beams at certain body stations due to fatigue cracking, with possible rapid decompression of the aircraft. David Punshon Delegate of the Civil Aviation Safety Authority 7 April 2008