{"id":"F2006B07459","name":"AD/TPE 331/48 - Fuel Control Unit Drive Shaft Spline Wear","slug":"ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49815,"registerId":"commonwealth-F2006B07459-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/48 - Fuel Control Unit Drive Shaft Spline Wear","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 331/48 Fuel Control Unit Drive Shaft Spline Wear 5/99\n\nRequirement: CANCELLED.\n\n \n\nNote: Operators can elect to remove or retain, reference in the Emergency Procedures Section of the approved flight manual (AFM) to a procedure to be carried out in the event of an uncommanded engine torque and turbine temperature increase. FAA Airworthiness Directive 94-26-07 refers.\n\n \n\nBackground:  This directive has been cancelled in response to advice that the drive shafts of concern have been removed from service and the inspection requirements of this directive are now reflected in the applicable engine maintenance manual inspection schedule.\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":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a cancellation instrument that narrows rather than expands scope. The original directive imposed mandatory inspection requirements; this instrument removes those requirements because the safety issue has been resolved through other means (component removal from service and incorporation into standard maintenance manuals). The scope has contracted to zero mandatory obligations."},"complexity_factors":["Extremely short document (under 200 words)","Single operative provision (cancellation of previous requirement)","No defined terms section","No cross-references to other legislation (only references to maintenance manuals and a foreign FAA directive for context)","Simple conditional logic (operators 'can elect' — optional action, not mandatory)","Background explanation provided in plain language"],"plain_english_summary":"This is a **cancelled airworthiness directive** for certain aircraft engines.\n\n**What it was:** Previously, owners of aircraft with AlliedSignal (Garrett/AiResearch) TPE 331 series turbine engines had to follow specific maintenance rules about inspecting the fuel control unit drive shaft for wear. This was to prevent dangerous situations where an engine might suddenly increase power and temperature without the pilot commanding it.\n\n**What changed:** The directive has been **cancelled** because the problematic drive shafts have been removed from all aircraft, and the inspection requirements are now covered in the standard engine maintenance manuals instead.\n\n**What operators can do:** Aircraft operators now have a choice — they can either remove or keep a reference in their flight manual's Emergency Procedures section about what to do if an engine suddenly surges (increases power and temperature unexpectedly). This refers to an older American safety rule (FAA Airworthiness Directive 94-26-07).\n\n**Who it affects:** Operators and maintainers of aircraft using TPE 331 series engines, particularly those who had previously been following this specific maintenance directive."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The instrument removes the original AD's mandatory inspection regime (Requirement: CANCELLED.) and transfers inspection responsibility into the engine maintenance manual schedule (Background). Operators retain discretion to manage AFM Emergency Procedures references (Note), so regulatory scope shifts from a stand‑alone AD to maintenance-manual governance."},"complexity_factors":["Very short instrument with few operative provisions (Requirement: CANCELLED.).","Primary action is cancellation rather than detailed regulatory requirements.","Compliance direction moved to existing engine maintenance manual (Background), creating reliance on separate document.","Operator discretion over AFM emergency-procedure reference (Note) reduces prescriptive obligations.","Cross-reference to external FAA AD increases dependence on another regulator's material but does not add domestic complexity."],"plain_english_summary":"AD/TPE 331/48 cancels a previous airworthiness directive about spline wear on the Fuel Control Unit drive shaft for AlliedSignal (Garrett/AiResearch) TPE331 engines. (Requirement: CANCELLED.) Operators may elect to add or retain an Emergency Procedures reference in the approved flight manual; the AD cross-references FAA AD 94-26-07. (Note.)\n\nThe cancellation is based on advice that affected drive shafts have been removed from service and that the inspection requirements are now captured in the engine maintenance manual schedule, so maintainers follow the engine MM rather than this AD. (Background.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear","history":"/api/acts/ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear/history","analysis":"/api/acts/ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear/analysis","conflicts":"/api/acts/ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear/conflicts","importantCases":"/api/acts/ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear/important-cases","documents":"/api/acts/ad-tpe-331-48-fuel-control-unit-drive-shaft-spline-wear/documents"}}