{"id":"F2006B07430","name":"AD/TPE 331/21 - Fuel Pump Spline Wear Inspection and/or Replacement","slug":"ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49705,"registerId":"commonwealth-F2006B07430-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/21 - Fuel Pump Spline Wear Inspection and/or 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 331/21 Fuel Pump Spline Wear Inspection\n\nand/or Replacement\n\nApplicability: TPE 331-3U-303G, -3UW-303G, -3U-304G.\n\n \n\nDocument: Garrett Service Bulletin No. TPE 331-73-0033, Rev. 5.;or AD/AIR-T/26 Amdt 2.\n\nCompliance: In accordance with the requirement document.\n\n \n\nBackground: This Directive is raised in issue to include the 331-3U-304G and extend the inspection interval for fuel pump spline inspection to 3000-3200 hours.\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\n3/86\n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1662},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":true,"description":"Expanded from previous versions to include the 331-3U-304G engine model and extended the inspection interval to 3000-3200 hours, whereas previous directives required more frequent inspections."},"complexity_factors":["Very short document with no interpretation section or defined terms","Single external technical reference (Garrett Service Bulletin)","Specific applicability limited to three engine model variants","Straightforward compliance requirement without nested conditions or exceptions"],"plain_english_summary":"This safety directive requires aircraft operators to inspect the fuel pump splines (the interlocking teeth that connect the fuel pump to the engine) on specific AlliedSignal (Garrett) TPE 331 turbine engines for wear damage.\n\n**Who it affects:**\nOwners and operators of aircraft fitted with TPE 331-3U-303G, -3UW-303G, or -3U-304G model engines.\n\n**What you must do:**\nFollow the inspection procedures in **Garrett Service Bulletin TPE 331-73-0033 (Revision 5)** to check for wear on the fuel pump splines. If wear is found, the parts must be replaced.\n\n**What's changed:**\nThis update adds the **331-3U-304G** engine model to the safety requirements and extends the inspection interval to **3,000–3,200 flight hours** (increasing the time allowed between inspections compared to previous requirements).\n\n**Why it matters:**\nWorn fuel pump splines can cause fuel delivery failures, potentially leading to engine shutdown or loss of power during flight. These inspections prevent catastrophic mechanical failures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement","history":"/api/acts/ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement/history","analysis":"/api/acts/ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement/analysis","conflicts":"/api/acts/ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement/conflicts","importantCases":"/api/acts/ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement/important-cases","documents":"/api/acts/ad-tpe-331-21-fuel-pump-spline-wear-inspection-and-or-replacement/documents"}}