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/B737/261 Main Deck Floor Beams 13/2005 Applicability: Model 737-100 and -200 series aircraft as listed in Boeing Service Bulletin 737-57-1210, or later FAA approved revision. Requirement: Action in accordance with the technical requirements of FAA AD 2001-14-20 Amdt 39-12331. Compliance: As specified in the Requirement document. This Airworthiness Directive becomes effective on 22 December 2005. Background: This Directive is prompted by reports of incidents involving fatigue cracking and corrosion in transport category aircraft that are approaching or have exceeded their design life goal. The Directive implements recommendations of the Airworthiness Assurance Task Force assigned to review the Model 737 series aircraft, which determined that, to assure long term continued operational safety, various structural inspections should be accomplished. The actions specified by this Directive are intended to prevent failure of the main deck floor beams at certain body stations due to fatigue cracking, which could result in rapid decompression and consequent reduced controllability of the aircraft. David Villiers Delegate of the Civil Aviation Safety Authority 10 November 2005