COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 727 Series Aeroplanes AD/B727/84 Amdt 3 Main Landing Gear Lock System 9/88 Applicability: All models to line number 1125. Requirement: Action in accordance with Boeing S.B. 727-32-0237 Rev 4. Note: FAA AD 79-04-01 R3 is referenced for earlier issues of this Directive. Compliance: Prior to 31 December 1988. Background: Aircraft were initially modified to provide higher strength components in the MLG lock system. Since that time there have been reports of missing nuts and the loss of a bolt.