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 250/43 Amdt 3 Second Stage Turbine Nozzle 2/90 Applicability: Allison Model 250-C28B, C28C engines fitted with P/N 6898952 second stage turbine nozzles. Requirement: Modify P/N 6898952 second stage turbine nozzles in accordance with Allison CEB- A-72-2044 Rev 4. Note: FAA AD 89-23-12 refers. Compliance: Prior to 31 March 1990. Background: This Directive has been amended to; 1. Delete reference to CSL 2030 which has been cancelled by the manufacturer, and 2. Require compliance with the requirements of CEB-A-72-2044 Rev 4, and 3. Make reference to FAA AD 89-23-12. The Amendment follows advice of another P/N 6898952 nozzle failure in service. Failure of the nozzle has resulted in uncontained second stage turbine wheel failure.