COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes AD/AC/95 Bleed Air System Leak Check 1/96 Applicability: All model 681, 690, 690A and 690B series aircraft. Requirement: Action in accordance with Twin Commander Mandatory Service Bulletin No 221. Compliance: At next annual inspection or within 100 hours' time in service after 4 January 1996, whichever occurs first. Thereafter, reinspect at intervals not exceeding 12 months or 500 hours' time in service, whichever occurs first. Background: The manufacturer has advised that revised instructions for pressure leak checks will be incorporated into the maintenance manual at some future date. This AD is issued to give effect to the Service Bulletin prior to formal incorporation of the requirements in the maintenance system.