{"id":"F2006B07419","name":"AD/TPE 331/11 - High Speed Pinion Bearing Assembly - Replacement","slug":"ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49669,"registerId":"commonwealth-F2006B07419-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/11 - High Speed Pinion Bearing Assembly - Replacement","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 (Garrett/AiResearch) Turbine Engines - TPE 331 Series\n\n \n\nAD/TPE 331/11 High Speed Pinion Bearing Assembly - Replacement\n\n\n3/86\n\n \n\nApplicability: TPE-331-25AA, 25DA, 25FA, 43A, 47A, 55A, 57A, 61A, 43BL, 25AB, 47B, 25DB, 25FB, 55B, 71, 57B, 61B and 49.\n\n \n\nDocument: AiResearch TPE-331 SB No. 659, Rev. 3, or AD/AIR-T/12.\n\nCompliance: Before installation in an aircraft following next major reconditioning completed after 31 May 1972.\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","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2117},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow technical scope targeting a specific mechanical component replacement on designated engine models. No evidence of scope expansion beyond the original bearing assembly safety requirement."},"complexity_factors":["Compliance triggered by specific maintenance event (major reconditioning) occurring after a historical date (31 May 1972)","References external technical service bulletin (SB No. 659) for detailed implementation instructions","Applicability spans 17 specific engine model variants requiring precise identification"],"plain_english_summary":"**What this does:** This Airworthiness Directive (AD) is a mandatory safety order requiring the replacement of the **high-speed pinion bearing assembly** in specific AlliedSignal (Garrett/AiResearch) TPE 331 aircraft turbine engines.\n\n**Who it affects:** Aircraft operators using TPE-331 engines, specifically models: -25AA, -25DA, -25FA, -43A, -47A, -55A, -57A, -61A, -43BL, -25AB, -47B, -25DB, -25FB, -55B, -71, -57B, -61B, and -49.\n\n**What you must do:** Before installing one of these engines in an aircraft following its next **major reconditioning** (significant overhaul) completed after 31 May 1972, you must replace the high-speed pinion bearing assembly.\n\n**Why it matters:** This prevents catastrophic engine failures caused by bearing defects. The directive references technical guidelines in **AiResearch Service Bulletin No. 659** to ensure proper replacement procedures are followed."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement","history":"/api/acts/ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement/history","analysis":"/api/acts/ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement/analysis","conflicts":"/api/acts/ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement/conflicts","importantCases":"/api/acts/ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement/important-cases","documents":"/api/acts/ad-tpe-331-11-high-speed-pinion-bearing-assembly-replacement/documents"}}