COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES General Electric Turbine Engines - CF6 Series AD/CF6/12 Amdt 2 Turbine Mid Frame Aft Circumferential Weld 3/91 Applicability: CF6-50/-45 series. Requirement: Action in accordance with the technical requirements of FAA AD 90-23-15 (Amdt 39-6754). Note: GE SB 72-957 Rev. 2 refers. Compliance: As specified in the Requirement Document. Background: The AD was initially raised to mandate the requirements of GE 72-957 which introduced inspections to insure against conditions which could release hot air into the core cowl cavity. Two such events resulted in take-off aborts due to fire warning indications. This amendment is raised to update the requirement in accordance with the FAA AD incorporating the latest revision of the manufacturer's SB covering the problem. It extends inspection intervals for certain engines on the basis of service experience.