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 250/11 Amdt 3 Engine Improvement - Introduction of "Blue Ribbon" Modifications 4/71 Applicability: All 250-C18 series. Document: 1. Allison Commercial Engine Bulletins numbered 250 CEB 57, 58, 59 Rev. 1, 61, 62, 63, 65, 66, 67, 68, 69 (or 98) 70, 72, 73, 74, (or 105), 75 (or 104), 76, 77, 103, 79, 80, 81, 85 and 89; or 2. FAA AD 69-26-3. Compliance: 1. At next overhaul after 29 May 1970 but not later than 750 hours' time in service since last overhaul or since new if never overhauled, modify the engine in accordance with the applicable Allison CEBs listed in this AD. 2. At next overhaul after 29 May 1970 but not later than 1125 hours' time in service since last overhaul or since new if never overhauled, modify the power and accessories gearbox in accordance with the applicable Allison CEBs listed in this AD.