COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AlliedSignal (Lycoming) Turbine Engines - ALF502 and LF507 Series AD/ALF/9 Amdt 1 Third Stage Turbine Rotor Assembly 11/88 Applicability: ALF 502 L and R series with third stage turbine rotor assemblies whose serial numbers are listed in the Requirement Documents. Requirement: Remove from service those third stage turbine rotor assemblies P/N 2-143-040-16 with serial numbers listed in Lycoming Service Bulletins No. A-ALF 502L-72-0189 Rev 1 and A-ALF 502R-72-0189 Rev 1. Compliance: In accordance with the schedules laid down in Section D of the relevant Requirement Document. Background: This Directive is amended to reflect Rev 1 to each of the Requirement documents which updates Appendix 1 lists of affected rotor assemblies. The Directive was issued to remove from service those third stage turbine rotor assemblies which have been identified with suspect heat treatment during manufacture. Suspect rotors may suffer disc tenon deformation with subsequent blade release resulting in engine damage.