{"id":"F2006B02248","name":"AD/AL 250/31 - Fuel System - Check Valve Assembly - Installation","slug":"ad-al-250-31-fuel-system-check-valve-assembly-installation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41478,"registerId":"commonwealth-F2006B02248-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/31 - Fuel System - Check Valve Assembly - Installation","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 250/31 Fuel System - Check Valve Assembly - Installation\n\nApplicability: 250-C20 Engine Assemblies prior to S/N CAE 823424. 250-C20B Engine\n\n# 5/78\n\nAssemblies prior to S/N CAE 830490. 250-B17 Engine Assemblies prior to S/N CAE 870060. 250-B17B Engine Assemblies prior to S/N CAE 880190.\n\n \n\nDocument: 1. Allison 250-C20B CEB 1101R1; or\n\n \n\n2. Allison 250-B17/B17B TP CEB 1078R1.\n\n \n\nCompliance: Before 30 November 1978.\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":1926},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow scope: mandating a specific safety modification (fuel system check valve installation) to specific Allison engine models. There is no expansion beyond the original fuel system safety issue."},"complexity_factors":["Single, unambiguous maintenance task","No conditional exceptions or nested logic","Clear applicability limited to four specific engine models by serial number","Simple calendar deadline with no alternative compliance methods"],"plain_english_summary":"This Airworthiness Directive mandates that owners/operators of specified Allison 250-series turbine engines (certain 250‑C20, 250‑C20B, 250‑B17 and 250‑B17B serial ranges) install a fuel system check‑valve per the Allison service bulletins to prevent leaks, engine stoppage or fire. It is legally binding and affected aircraft may not fly until the modification was completed (deadline: 30 Nov 1978)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-31-fuel-system-check-valve-assembly-installation","history":"/api/acts/ad-al-250-31-fuel-system-check-valve-assembly-installation/history","analysis":"/api/acts/ad-al-250-31-fuel-system-check-valve-assembly-installation/analysis","conflicts":"/api/acts/ad-al-250-31-fuel-system-check-valve-assembly-installation/conflicts","importantCases":"/api/acts/ad-al-250-31-fuel-system-check-valve-assembly-installation/important-cases","documents":"/api/acts/ad-al-250-31-fuel-system-check-valve-assembly-installation/documents"}}