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 250/5 Amdt 1 Engine Compressor - Modifications 10/68 Applicability: All 250-C18 engines. Document: Allison CEBs No. 250 CEB-51 and -52. Compliance: Before 25 October 1968.