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 250/19 Fuel System - Power Turbine Governor to Control Fuel Tube Clamp - Installation 9/73 Applicability: All 250-C20 CECO-Controlled Engine Assemblies prior to S/No. CAE 820908. Document: Allison 250 CEB No. 1040, Rev. 1. Compliance: Within 50 hours' time in service after 28 September 1973.