COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Airbus Industrie A319, A320 and A321 Series Aeroplanes AD/A320/75 Longitudinal Floor Beams at Frame 43 2/97 Applicability: Airbus A320, all models, all serial numbers, without Airbus Industrie Modification 20904 or Airbus Industrie Service Bulletin (SB) A320-53-1008 incorporated. Requirement: Inspect the bottom flanges of the longitudinal floor beams at frame 43 in accordance with Airbus Industrie SB A320-53-1085. Note: French DGAC AD 96-236-089(B) refers. Compliance: Inspect before exceeding 20 000 flights. Re-inspect at intervals not exceeding 6000 flights or, if cracks are detected, re-inspect at the intervals defined in Airbus Industrie SB A320-53-1085. Note: Modification of the aircraft in accordance with Airbus Industrie SB A320-53-1008 is terminating action for this Directive. This Airworthiness Directive becomes effective on 30 January 1997. Background: During the full-scale fatigue test of the airframe, cracks were detected in the bottom flange of the longitudinal floor beams, which attach the pressure diaphragm at frame 43. This directive is issued to detect cracks in this area before the structural integrity of the airframe is affected.