{"id":"F2006B02258","name":"AD/AL 250/47 - First Stage Turbine Wheel P/N 6853306 - Replacement","slug":"ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41488,"registerId":"commonwealth-F2006B02258-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/47 - First Stage Turbine Wheel P/N 6853306 - Replacement","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\n# AD/AL 250/47  First Stage Turbine Wheel P/N 6853306 - Replacement\n\nApplicability: All 250-C20 and 250-B17 models. Document:  1. Allison 250-C20 CEB-1048; or\n\n2. Allison B17 TP CEB-1031.\n\n \n\nCompliance: As per reference document.\n\n# 7/81\n\n \n\nBackground:  This Directive is issued to prevent first stage turbine wheel failures. Several failures of P/N 6853306 wheels have occurred overseas.\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\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1358},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains a narrow, targeted scope focused solely on the replacement of the identified defective turbine wheel. It has not expanded beyond its original safety purpose to address unrelated maintenance or operational issues."},"complexity_factors":["Single, discrete maintenance requirement with no exceptions or conditional provisions","Brief text with only three operative sections (Applicability, Document, Compliance)","Relies on external technical service bulletins for detailed compliance instructions rather than embedding complex procedures"],"plain_english_summary":"**What this does:** This is a mandatory safety order requiring owners and operators of specific Allison turbine engines to replace a dangerous component—the first stage turbine wheel with part number 6853306.\n\n**Who it affects:** Anyone responsible for aircraft or equipment powered by Allison 250-C20 or 250-B17 engine models.\n\n**Why it matters:** These particular turbine wheels have failed multiple times overseas, creating a serious risk of engine failure and potential crashes. The directive forces replacement of these parts according to specific manufacturer service bulletins (technical documents called CEB-1048 for the C20 model and CEB-1031 for the B17 model) to prevent accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement","history":"/api/acts/ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement/history","analysis":"/api/acts/ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement/analysis","conflicts":"/api/acts/ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement/conflicts","importantCases":"/api/acts/ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement/important-cases","documents":"/api/acts/ad-al-250-47-first-stage-turbine-wheel-p-n-6853306-replacement/documents"}}