COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 727 Series Aeroplanes AD/B727/89 Amdt 4 Cockpit Side Window - "F-N" Window Post 8/95 Applicability: B727 line numbers 1 to 1164 inclusive. Requirement: Inspect visually, by eddy current and by X-ray as applicable, the "F-N" window post in accordance with Boeing Service Bulletin (SB) 727-53-0086, Revision 11. Note: FAA AD 93-05-17 refers. Compliance: Inspect at the thresholds and intervals specified in Tables I and II of Boeing SB 727-53-0086, Revision 11. Background: One hundred and sixty two cracks have been experienced on 707, 727 and 737 aircraft in the subject region, including aircraft that have been modified and repaired to earlier issues of the SB. This SB has been identified by the B727 Ageing Aircraft Structures Working Group as a safety of flight item and requires the area to be modified, Directive AD/B727/118 refers. Amendment 3 extended the inspection area to the structure above the cockpit window. Amendment 4 corrects the applicability.