{"id":"F2006B02306","name":"AD/ALF/10 - Third Stage Turbine Rotor Assembly","slug":"ad-alf-10-third-stage-turbine-rotor-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41536,"registerId":"commonwealth-F2006B02306-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ALF/10 - Third Stage Turbine Rotor Assembly","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAlliedSignal (Lycoming) Turbine Engines \\- ALF502 and LF507 Series\n\nAD/ALF/10 Third Stage Turbine Rotor Assembly 6/89\n\nApplicability: ALF 502L and R series with third stage rotor assemblies whose serial numbers are listed in the Requirement documents.\n\nRequirement: 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.\n\nCompliance: Unless already accomplished, in accordance with the schedules laid down in Section D of the relevant Requirement Document.\n\nBackground: 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.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The provided AD text sets a specific, narrow requirement (remove listed third-stage rotor assemblies from ALF 502L/R engines) and delegates timing and procedural detail to the referenced Requirement Documents. The text contains no statement that the scope has been altered from an earlier or original intent; based on the AD alone, the scope remains the targeted removal of the identified parts as described (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow technical scope: applies only to ALF 502L and R series engines with specific rotor part numbers and listed serial numbers (Applicability; Requirement).","Dependence on external documents: requires consulting Appendix 1 of two Lycoming service bulletins and Section D of the relevant Requirement Document to identify affected serial numbers and compliance timing (Requirement; Compliance).","Operational implementation: removal from service creates scheduling, inspection and maintenance tasks for owners/operators (Requirement; Compliance).","Safety-critical technical issue: defect (suspect heat treatment) can lead to mechanical failure (disc tenon deformation and blade release), so actions are time-sensitive and require accurate identification of parts (Background)."],"plain_english_summary":"This AD requires removal from service of certain third‑stage turbine rotor assemblies (P/N 2‑143‑040‑16) installed in AlliedSignal (Lycoming) ALF 502L/R engines when their serial numbers match the lists in the referenced service bulletin appendices, because suspect heat treatment may cause tenon deformation and blade release. Owners/operators must remove listed rotors per the Requirement Document’s schedule; the AD sets the mandate but not funding or replacement arrangements."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific manufacturing defect in specific engine models. It has not expanded beyond its original purpose of removing suspect rotor assemblies from service."},"complexity_factors":["Very short document (under 200 words)","Only 4 structural sections: Applicability, Requirement, Compliance, and Background","Single clear action required (removal of specific parts)","Minimal defined terms (only standard aviation references like P/N for Part Number)","No nested conditions or exceptions — straightforward applicability test based on serial numbers","Cross-references limited to two specific service bulletins with clear section references"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it as a recall notice, but for aircraft parts rather than cars.\n\n**What it does:** It orders airlines and aircraft operators to immediately remove specific turbine rotor assemblies from certain AlliedSignal (Lycoming) jet engines. These parts are the \"third stage turbine rotor assemblies\" — critical components in the engine's power section.\n\n**Who it affects:** Anyone operating aircraft with ALF 502L or ALF 502R series engines that have rotor assemblies with specific serial numbers listed in a referenced service bulletin.\n\n**Why it matters:** The affected rotors were manufactured using a faulty heat treatment process. This defect can cause the metal to deform at the points where turbine blades attach (called \"disc tenons\"). If these tenons fail, the blades can break loose, destroying the engine and potentially causing a crash. The directive prevents this by grounding the suspect parts before they fail.\n\n**What operators must do:** Check if their engines have the affected serial numbers. If they do, remove those rotor assemblies from service according to the timeline in the referenced Lycoming service bulletins."}},"importantCases":[],"_links":{"self":"/api/acts/ad-alf-10-third-stage-turbine-rotor-assembly","history":"/api/acts/ad-alf-10-third-stage-turbine-rotor-assembly/history","analysis":"/api/acts/ad-alf-10-third-stage-turbine-rotor-assembly/analysis","conflicts":"/api/acts/ad-alf-10-third-stage-turbine-rotor-assembly/conflicts","importantCases":"/api/acts/ad-alf-10-third-stage-turbine-rotor-assembly/important-cases","documents":"/api/acts/ad-alf-10-third-stage-turbine-rotor-assembly/documents"}}