{"id":"F2006B02323","name":"AD/ALF/9 Amdt 1 - Third Stage Turbine Rotor Assembly","slug":"ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41553,"registerId":"commonwealth-F2006B02323-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ALF/9 Amdt 1 - 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/9\n\nAmdt 1\n\n  \nThird Stage Turbine Rotor Assembly 11/88\n\nApplicability: ALF 502 L and R series with third stage turbine 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 Lycoming Service Bulletins No. A-ALF 502L-72-0189 Rev 1 and A-ALF 502R-72-0189 Rev 1.\n\nCompliance: In accordance with the schedules laid down in Section D of the relevant Requirement Document.\n\nBackground: 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.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment remains tightly scoped to its original purpose. It updates the lists of affected serial numbers in the referenced service bulletins but does not expand the directive to new engine models, new part numbers, or new types of defects. The core scope — addressing heat treatment defects in ALF 502 third stage turbine rotors — remains unchanged."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (\"Compliance\" refers to external documents)","No nested conditional logic — simple binary applicability test (part number + serial number match)","Single requirement with clear action (remove from service)","Cross-references limited to 2 specific external service bulletins and their Section D schedules","No exceptions or exemptions stated","Straightforward amendment purpose (updating appendix lists in referenced documents)"],"plain_english_summary":"This CASA Airworthiness Directive legally orders removal from service of specific third-stage turbine rotor assemblies (P/N 2-143-040-16) in AlliedSignal/Lycoming ALF 502 L/R engines because some rotors were improperly heat‑treated, risking disc‑tenon deformation and blade release that could destroy an engine and endanger the aircraft. It affects operators and maintenance organisations with rotors listed by serial number in the two referenced Lycoming service bulletins; Amdt 1 revises that serial‑number list."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The amendment (Rev 1 to the Requirement Documents) updates the Appendix 1 lists of affected rotor serial numbers but does not alter the underlying mandatory requirement to remove from service the listed third-stage turbine rotor assemblies. The core scope and action remain the same (Background/Requirement)."},"complexity_factors":["Narrow, technical scope limited to a specific part number and listed serial numbers (Applicability/Requirement).","Dependence on external Requirement Documents/service bulletins for the definitive list of affected rotors (Requirement/Background).","Mandatory safety action with prescribed compliance timing but no complex regulatory tests or conditional exemptions (Compliance).","Operational scheduling and logistical burden on operators to remove/replace parts within the stated schedules (Compliance).","Amendment alters the appendix lists only, not the substantive removal obligation, reducing interpretive complexity (Background)."],"plain_english_summary":"**What this does:** This Airworthiness Directive requires certain third-stage turbine rotor assemblies (P/N 2-143-040-16) in AlliedSignal (Lycoming) ALF502 L and R engines to be removed from service if their serial numbers are listed in the cited service bulletins. The action targets rotors with suspected faulty heat treatment that can deform disc tenons and cause blade release (Background).\n\n**Who pays and how it works:** Aircraft operators must remove and replace affected rotors according to the Compliance schedule in the Requirement Document; maintenance organisations must follow the service-bulletin lists (Applicability/Requirement/Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly","history":"/api/acts/ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly/history","analysis":"/api/acts/ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly/analysis","conflicts":"/api/acts/ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly/conflicts","importantCases":"/api/acts/ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly/important-cases","documents":"/api/acts/ad-alf-9-amdt-1-third-stage-turbine-rotor-assembly/documents"}}