COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 727 Series Aeroplanes AD/B727/165 Upper and Lower Sills of Number 1 Cargo Door 1/2000 Applicability: All Model 727-200 series aircraft. Requirement: Action in accordance with the technical requirements of FAA AD 99-23-13 Amdt 39- 11409. Note: Boeing Service Bulletin 727-53A0219 Revision 1 refers. Compliance: As specified in the Requirement document for the initial and repetitive inspections, with a revised effective date of 31 December 1999. This Airworthiness Directive becomes effective on 31 December 1999. Background: The FAA received reports of fatigue cracks in certain structures adjacent to the number 1 cargo door cutout at the forward and aft doorway frames. Such cracking could result in rapid decompression of the fuselage and consequent reduced structural integrity of the aircraft.