{"id":"F2006B02286","name":"AD/AL 250/77 - Third Stage Turbine Wheel P/N 23001977","slug":"ad-al-250-77-third-stage-turbine-wheel-p-n-23001977","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41516,"registerId":"commonwealth-F2006B02286-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/77 - Third Stage Turbine Wheel P/N 23001977","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 250/77 Third Stage Turbine Wheel P/N 23001977 4/96 TX\n\nApplicability: All 250-C28 series engines fitted with a P/N 23001977 third stage turbine wheel. Requirement:               Remove applicable third stage turbine wheels from service in accordance with Allison\n\nAlert Commercial Engine Bulletin CEB A72-2176.\n\n \n\nCompliance: Effective 2 February 1996; as detailed in the requirement document.\n\n \n\nBackground:  This Directive has been issued to require certain third stage turbine wheels to be removed from service. The requirement reflects advice from the manufacturer of three P/N 23001977 third stage blade shroud failures.\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\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2268},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific mechanical defect in a specific aircraft engine component. The scope remains limited to the removal of the identified faulty turbine wheels as originally intended."},"complexity_factors":["Single, specific mechanical part identified by part number","One clear action required (removal from service)","No nested exceptions or conditional logic beyond simple applicability test","Refers to only one external document (manufacturer bulletin)","Document length is less than one page"],"plain_english_summary":"This is a **safety order** (called an Airworthiness Directive) issued by the aviation safety regulator. It requires owners or operators of specific aircraft engines to **remove a faulty turbine component** from service.\n\n**What is affected:**\n- Allison 250-C28 series aircraft engines fitted with a specific part: third stage turbine wheel part number 23001977\n\n**What must be done:**\n- Remove the identified turbine wheels from the engine\n- Follow the manufacturer's instructions in bulletin CEB A72-2176\n\n**Why this matters:**\nThe manufacturer reported **three failures** of blade shrouds on this specific part. If the shroud fails during flight, it could cause serious engine damage or failure, potentially leading to an accident.\n\n**When:**\nThe requirement took effect on 2 February 1996.\n\nThis type of directive is mandatory—aircraft cannot legally fly until the defective part is replaced or removed according to the specified instructions."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-77-third-stage-turbine-wheel-p-n-23001977","history":"/api/acts/ad-al-250-77-third-stage-turbine-wheel-p-n-23001977/history","analysis":"/api/acts/ad-al-250-77-third-stage-turbine-wheel-p-n-23001977/analysis","conflicts":"/api/acts/ad-al-250-77-third-stage-turbine-wheel-p-n-23001977/conflicts","importantCases":"/api/acts/ad-al-250-77-third-stage-turbine-wheel-p-n-23001977/important-cases","documents":"/api/acts/ad-al-250-77-third-stage-turbine-wheel-p-n-23001977/documents"}}