{"id":"F2006B07255","name":"AD/T53/7 - Improved Gas Producer Turbine Rotor Blades - Introduction","slug":"ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49154,"registerId":"commonwealth-F2006B07255-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/T53/7 - Improved Gas Producer Turbine Rotor Blades - Introduction","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)  AlliedSignal (Lycoming) Turbine Engines - T53 Series\n\n \n\nAD/T53/7 Improved Gas Producer Turbine Rotor Blades - Introduction\n\nApplicability: All models T5309B, T5309C, T5311A and T5311B. Document:  1. Lycoming Field Service Bulletin No. 0021; or\n\n2. AD/LYC-T/7 Compliance: Before 30 April 1971.\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\n \n\n \n\n \n\n\n1/86\n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1107},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow technical scope regarding the introduction of improved rotor blades for specific engine models."},"complexity_factors":["Extremely short single-purpose directive","No legislative cross-references or conditional clauses","Limited to four specific engine models","Clear, unambiguous compliance requirement"],"plain_english_summary":"This directive mandates safety upgrades for specific helicopter turbine engines. If you operate an aircraft with a Lycoming T53 series engine (models T5309B, T5309C, T5311A, or T5311B), you must replace or modify the **gas producer turbine rotor blades** (the fan-like components that compress air in the engine) with improved versions.\n\n**Key requirements:**\n*   **Who it affects:** Operators of aircraft fitted with the specified AlliedSignal (Lycoming) T53 turbine engines\n*   **What you must do:** Install improved rotor blades according to Lycoming Field Service Bulletin No. 0021 (or equivalent directive AD/LYC-T/7)\n*   **Why it matters:** The original blades were susceptible to fatigue or failure, which could cause engine malfunction or catastrophic damage during flight\n*   **Compliance deadline:** Before 30 April 1971 (historical directive)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction","history":"/api/acts/ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction/history","analysis":"/api/acts/ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction/analysis","conflicts":"/api/acts/ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction/conflicts","importantCases":"/api/acts/ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction/important-cases","documents":"/api/acts/ad-t53-7-improved-gas-producer-turbine-rotor-blades-introduction/documents"}}