{"id":"F2006B07253","name":"AD/T53/5 - Accessory Drive Gearbox - Rework","slug":"ad-t53-5-accessory-drive-gearbox-rework","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49148,"registerId":"commonwealth-F2006B07253-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/T53/5 - Accessory Drive Gearbox - Rework","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/T53/5 Accessory Drive Gearbox - Rework 1/86\n\nApplicability: All models as listed in OMB No. 0028. Document:  1. Lycoming SB No. 41; or\n\n2.        Lycoming Overhaul Mod. Bulletin No. 0028; or\n\n \n\n3.        Lycoming Field Service Bulletin No. 0010; or\n\n \n\n4.        AD/LYC-T/3A.\n\n \n\nCompliance: Prior to installation in an aircraft following next reconditioning completed after 30 June 1972.\n\n \n\nNote: Engines complying with the previous issue of this Directive require no further rework.\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":2280},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow, technical scope targeting only accessory drive gearbox rework for the T53 engine series. No expansion of regulatory scope beyond the original safety maintenance purpose is evident."},"complexity_factors":["Substantive technical requirements are entirely outsourced to external manufacturer documents (Lycoming Service Bulletins)","Minimal conditional logic—only a single date-based compliance trigger (post-30 June 1972) and one exemption clause","No defined terms or interpretation section; extremely concise drafting typical of 1986 vintage airworthiness directives"],"plain_english_summary":"This AD requires reworking the accessory drive gearbox on AlliedSignal (Lycoming) T53-series turbine engines before the engine is returned to service after any reconditioning completed on or after 30 June 1972. It affects owners/operators of aircraft using these engines and must be done per Lycoming service/overhaul/field bulletins (or prior AD) — engines already compliant with the earlier directive are exempt. The change prevents failure of a critical power-transmission component that runs essential systems."}},"importantCases":[],"_links":{"self":"/api/acts/ad-t53-5-accessory-drive-gearbox-rework","history":"/api/acts/ad-t53-5-accessory-drive-gearbox-rework/history","analysis":"/api/acts/ad-t53-5-accessory-drive-gearbox-rework/analysis","conflicts":"/api/acts/ad-t53-5-accessory-drive-gearbox-rework/conflicts","importantCases":"/api/acts/ad-t53-5-accessory-drive-gearbox-rework/important-cases","documents":"/api/acts/ad-t53-5-accessory-drive-gearbox-rework/documents"}}