COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Allison Turbine Engines - 250 Series AD/AL 250/25 Amdt 1 Power Turbine Outer Coupling Nut - Inspection 10/77 Applicability: All model 250-C18, -C20, -C20B, B15G, B17 and B17B series engines fitted with power turbine outer coupling Nut P/N 6846278. Document: Allison 250-C18, CSL-88, Rev. 3; OR 250-C20/C20B CSL-1060, Rev. 3; or 250- B15G TP CSL-25, Rev. 3; OR 250-B17/B17B TP CSL-1030, Rev. 3; OR FAA AD 77-15-12, Amendment No. 39-2977. Compliance: As detailed in the requirement documents.