{"id":"F2006B02250","name":"AD/AL 250/33 - Fourth Stage Compressor Wheel - Retirement","slug":"ad-al-250-33-fourth-stage-compressor-wheel-retirement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41480,"registerId":"commonwealth-F2006B02250-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/33 - Fourth Stage Compressor Wheel - Retirement","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Allison Turbine Engines - 250 Series\n\n \n\nAD/AL 250/33 Fourth Stage Compressor Wheel - Retirement 5/79\n\nApplicability: All 250-C18 and 250-B15G series fitted with compressor wheels P/N 6856754 or 6871444.\n\n \n\nDocument: 1. Allison 250-C18 CSL-96; or\n\n \n\n2. Allison B15G TP CSL-36.\n\n \n\nCompliance: Within 100 hours’ time in service after 31 May 1979.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":796},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be the original 1979 directive maintaining its narrow, specific scope: mandating retirement of identified defective compressor wheels in specific Allison engine models. No evidence of scope creep or expansion beyond this original safety mandate."},"complexity_factors":["Short single-issue directive with straightforward applicability clause","References two external technical service bulletins (CSL-96 and CSL-36) for detailed procedures","Simple time-based compliance trigger (100 hours after specific date)","Limited to two specific part numbers and two engine models"],"plain_english_summary":"**What this does:** This is a safety order (called an Airworthiness Directive) that requires owners and operators of specific Allison turbine engines to remove certain faulty compressor wheels from service before they fail.\n\n**Who it affects:** Anyone operating aircraft with Allison 250-C18 or 250-B15G engines that have compressor wheels with part numbers 6856754 or 6871444 installed.\n\n**What must be done:** The fourth-stage compressor wheels must be retired (permanently removed from use) within 100 flight hours after 31 May 1979.\n\n**Why it matters:** Compressor wheels spin at extremely high speeds. If these specific wheels fail in flight, they can shatter and destroy the engine, potentially causing catastrophic damage to the aircraft and endangering lives. This directive forces replacement before fatigue causes failure.\n\n**Technical details:** Operators must follow the procedures in either Allison document CSL-96 (for C18 engines) or CSL-36 (for B15G engines) to ensure compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-33-fourth-stage-compressor-wheel-retirement","history":"/api/acts/ad-al-250-33-fourth-stage-compressor-wheel-retirement/history","analysis":"/api/acts/ad-al-250-33-fourth-stage-compressor-wheel-retirement/analysis","conflicts":"/api/acts/ad-al-250-33-fourth-stage-compressor-wheel-retirement/conflicts","importantCases":"/api/acts/ad-al-250-33-fourth-stage-compressor-wheel-retirement/important-cases","documents":"/api/acts/ad-al-250-33-fourth-stage-compressor-wheel-retirement/documents"}}