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/10 Third Stage Turbine Rotor Assembly 6/89 Applicability: ALF 502L and R series with third stage 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 Appendix 1 of Lycoming Service Bulletin No. ALF 502L-72-210 and ALF 502R-72-210. Compliance: Unless already accomplished, in accordance with the schedules laid down in Section D of the relevant Requirement Document. Background: This Directive is issued to remove from service those third stage turbine rotor assemblies which have been identified as having received suspect heat treatment procedure during manufacture. Suspect rotors may suffer disc tenon deformation with subsequent blade release resulting in engine damage.