{"id":"F2006B02271","name":"AD/AL 250/6 Amdt 1 - Power Turbine Governor - Modification","slug":"ad-al-250-6-amdt-1-power-turbine-governor-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41501,"registerId":"commonwealth-F2006B02271-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/6 Amdt 1 - Power Turbine Governor - Modification","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 250/6\n\nAmdt 1\n\n\nPower Turbine Governor - Modification 5/70\n\n \n\nApplicability: All models 250-C18 and 250-C18A engines fitted with power turbine governor Allison P/Ns 6856291, 6858482 or 6870546.\n\n \n\nDocument: 1. Allison CEB No. 250 CEB-22; or\n\n \n\n2. Allison CEB No. 250 CEB-77.\n\n \n\nCompliance: Before 1 July 1970.\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":1992},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"As Amendment 1 to the original directive, this maintains the original focused scope of governing airworthiness for specific power turbine governors. It does not expand beyond the original safety intent of ensuring modifications are made to the identified Allison engine models."},"complexity_factors":["Extremely short text (less than one page)","Narrow applicability limited to 2 engine models and 3 specific part numbers","Single, clear compliance deadline","Technical details delegated to external manufacturer documents (CEBs) rather than included in the legislative text"],"plain_english_summary":"**What it does:** This directive requires owners and operators of specific Allison turbine engines to modify the **power turbine governor** (the component that controls and stabilises engine speed to prevent overspeeding or power loss) before 1 July 1970.\n\n**Who it affects:** Anyone operating aircraft with **Allison 250-C18 or 250-C18A engines** fitted with power turbine governors bearing part numbers **6856291, 6858482, or 6870546**.\n\n**What must be done:** The modification must be performed in accordance with one of two manufacturer bulletins:\n- Allison Commercial Engine Bulletin (CEB) No. 250 CEB-22, **or**\n- Allison CEB No. 250 CEB-77\n\nThese bulletins contain the specific technical instructions for the modification.\n\n**Why it matters:** Faulty power turbine governors can cause catastrophic engine failure or loss of power control. This rule mandated a safety-critical update to ensure these specific engine components met airworthiness standards by the 1970 deadline."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-6-amdt-1-power-turbine-governor-modification","history":"/api/acts/ad-al-250-6-amdt-1-power-turbine-governor-modification/history","analysis":"/api/acts/ad-al-250-6-amdt-1-power-turbine-governor-modification/analysis","conflicts":"/api/acts/ad-al-250-6-amdt-1-power-turbine-governor-modification/conflicts","importantCases":"/api/acts/ad-al-250-6-amdt-1-power-turbine-governor-modification/important-cases","documents":"/api/acts/ad-al-250-6-amdt-1-power-turbine-governor-modification/documents"}}