{"id":"F2006B02281","name":"AD/AL 250/70 - No. 8 Bearing Scavenge Line Air/Oil Separator","slug":"ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41511,"registerId":"commonwealth-F2006B02281-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/70 - No. 8 Bearing Scavenge Line Air/Oil Separator","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 250/70 No. 8 Bearing Scavenge Line Air/Oil Separator 8/86\n\nApplicability: 250-C28B and C28C series engines with engine and turbine serial numbers listed in the Requirement Document.\n\n \n\nRequirement: Modify the engine oil system in accordance with Allison Alert CEB-A-72-2138 dated 15 May 1986.\n\n \n\nCompliance: Within 100 hours of engine operation after 31 August 1986 but no later than 31 January 1987.\n\n \n\nBackground:  This Directive is issued to install an air/oil separator in the No. 8 bearing scavenge line to improve venting of the No. 8 bearing oil sump. Excess pressure in the No. 8 bearing sump may result in internal oil fire and cause a No. 1 turbine wheel failure.\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":1939},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow technical scope regarding a specific mandatory modification to prevent oil sump pressurization in designated Allison engines. It has not expanded beyond the original safety-critical maintenance requirement."},"complexity_factors":["Single, unambiguous technical requirement with no alternative compliance methods","Clear applicability limited to specific engine models and serial number ranges","Fixed compliance deadline with no conditional exceptions or extensions","No defined terms, cross-references to other legislation, or nested conditional logic","Incorporates only one external technical document by reference"],"plain_english_summary":"**What this does:** This is a mandatory safety order requiring owners to modify the oil system in specific Allison turbine engines by installing an air/oil separator in the No. 8 bearing scavenge line (the pipe that drains oil away from the bearing). The modification must be done exactly as specified in the referenced technical document (Allison Alert CEB-A-72-2138).\n\n**Who it affects:** Owners and operators of Allison 250-C28B and 250-C28C series turbine engines with specific serial numbers listed in the technical requirement document.\n\n**Why it matters:** This prevents dangerous pressure buildup in the No. 8 bearing oil sump. Without this fix, excess pressure can cause an internal oil fire and lead to catastrophic failure of the No. 1 turbine wheel, which could destroy the engine and endanger the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator","history":"/api/acts/ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator/history","analysis":"/api/acts/ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator/analysis","conflicts":"/api/acts/ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator/conflicts","importantCases":"/api/acts/ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator/important-cases","documents":"/api/acts/ad-al-250-70-no-8-bearing-scavenge-line-air-oil-separator/documents"}}