{"id":"F2006B02318","name":"AD/ALF/4 - Compressor Vanes, Turbine Blades and Turbine Nozzle - Inspection and Replacement","slug":"ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41548,"registerId":"commonwealth-F2006B02318-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AD/ALF/4 Compressor Vanes, Turbine Blade","sectionType":"part","heading":"AD/ALF/4 Compressor Vanes, Turbine Blades and Turbine Nozzle - Inspection and Replacement","content":"# AD/ALF/4 Compressor Vanes, Turbine Blades and Turbine Nozzle \\- Inspection and Replacement\n\nApplicability: Lycoming Turbo Fan Engine Models ALF 502-L/L2 and ALF 502-R3/R4. Document: 1. Avco Lycoming SB ALF 502-72-0012, Rev. 2.\n\n    2. Avco Lycoming SB ALF 502-72-0025, Rev. 1.\n\n    3. Avco Lycoming SBALF 502-72-0027.\n\n    4. Avco Lycoming SBALF 502-72-0021; or\n\n    5. AD/LYC-T/21.\n\nNote: FAA AD 82-25-10 Amendment 39-4511 refers.","sortOrder":0},{"sectionNumber":"1/86","sectionType":"part","heading":"1/86","content":"# AD/ALF/4 Compressor Vanes, Turbine Blades and Turbine Nozzle \\- Inspection and Replacement\n\nApplicability: Lycoming Turbo Fan Engine Models ALF 502-L/L2 and ALF 502-R3/R4. Document: 1. Avco Lycoming SB ALF 502-72-0012, Rev. 2.\n\n    2. Avco Lycoming SB ALF 502-72-0025, Rev. 1.\n\n    3. Avco Lycoming SBALF 502-72-0027.\n\n    4. Avco Lycoming SBALF 502-72-0021; or\n\n    5. AD/LYC-T/21.\n\nNote: FAA AD 82-25-10 Amendment 39-4511 refers.\n\n#   \n1/86","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be a standard, narrow airworthiness directive focused on specific engine components. The scope remains tightly constrained to the original safety issue — preventing failure of compressor vanes, turbine blades and nozzles in specified Lycoming engines. The reference to alternative compliance documents (the 5 options listed) is typical of ADs and does not represent scope creep."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined applicability criteria (specific engine models)","Simple conditional structure: comply with one of 5 listed documents","No nested exceptions or complex cross-referencing beyond the FAA AD note","No interpretation section or defined terms","Straightforward mandate: inspect and replace per specified service bulletins"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's aviation regulator (CASA). It requires owners and operators of specific **Lycoming ALF 502 turbofan aircraft engines** to inspect and replace certain engine parts (compressor vanes, turbine blades, and turbine nozzles) according to manufacturer service bulletins.\n\n**Who it affects:**\n- Operators of aircraft using **Lycoming ALF 502-L/L2 or ALF 502-R3/R4 engines**\n- Maintenance organisations servicing these engines\n\n**What it requires:**\n- Mandatory inspection and replacement of critical rotating engine components\n- Compliance with specific manufacturer service bulletins (SB ALF 502-72-0012 Rev. 2, SB ALF 502-72-0025 Rev. 1, SBALF 502-72-0027, SBALF 502-72-0021) or an alternative Australian directive (AD/LYC-T/21)\n\n**Why it matters:**\nThese components operate under extreme stress. Failure can cause **catastrophic engine damage** and potential loss of aircraft. This AD prevents accidents by ensuring worn or defective parts are identified and replaced before they fail.\n\nThe directive references a corresponding **US Federal Aviation Administration (FAA) AD** (82-25-10), showing Australia harmonises with international safety standards."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The text specifies a narrow, model-specific scope (ALF 502-L/L2 and ALF 502-R3/R4) and lists the service bulletins and AD that govern inspection and replacement. The instrument contains no statement indicating a change from a prior broader or narrower scope; it simply imposes compliance via the referenced documents (Applicability; Document; Note)."},"complexity_factors":["Multiple cross-references to external technical documents (four Avco Lycoming service bulletins and AD/LYC-T/21) and a referenced FAA AD (Document; Note)","Highly technical subject matter (compressor vanes, turbine blades, turbine nozzle) requiring specialist maintenance skills","The instrument itself contains no procedural detail or inspection criteria—those are in the referenced documents, increasing the need to consult multiple sources","Narrow applicability to specific engine models, which reduces breadth but concentrates operational impact and record-keeping for affected operators (Applicability)","Enforcement, intervals and penalties are not specified in this text, leaving implementation and compliance monitoring to other instruments or regulatory practice"],"plain_english_summary":"This instrument requires inspection—and replacement where necessary—of compressor vanes, turbine blades and the turbine nozzle on Lycoming ALF 502 engines (models ALF 502‑L, L2, R3, R4). It does not set technical criteria itself but mandates compliance with specified Avco Lycoming service bulletins and an FAA airworthiness directive.\n\nIt affects aircraft operators, licensed maintenance organisations and parts suppliers, shifting costs and technical decision‑making to operators and the referenced SBs/AD."}},"importantCases":[],"_links":{"self":"/api/acts/ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement","history":"/api/acts/ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement/history","analysis":"/api/acts/ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement/important-cases","documents":"/api/acts/ad-alf-4-compressor-vanes-turbine-blades-and-turbine-nozzle-inspection-and-replacement/documents"}}