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/CF6/25 Fan Disks - Removal From Service 10/92 Applicability: CF6-50 and 80A series. Requirement: Action in accordance with the technical requirements of FAA AD 91-23-13. Compliance: As specified in the Requirement Document with an effective date of 17 September 1992. Background: This AD requires removal of certain Stage 1 Fan Disks from service. It results from the possibility of a metallurgical defect which could adversely affect the service life of the disc.