{"id":"F2006B04452","name":"AD/BELL 206/138 - Turbine Outlet Temperature Indicator","slug":"ad-bell-206-138-turbine-outlet-temperature-indicator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44289,"registerId":"commonwealth-F2006B04452-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 206/138 - Turbine Outlet Temperature Indicator","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters\n\nAD/BELL 206/138 Turbine Outlet Temperature Indicator 12/96\n\nApplicability: This Directive is applicable to all Bell Model 206L-1 helicopters equipped with Kratos turbine outlet temperature (TOT) indicators part number (P/N) 124.444-6 and 124.444-20.\n\nRequirement: Remove Kratos TOT indicator P/N 124.444-6 or 124.444-20 and replace it with any other TOT indicator approved for use on the Bell Model 206L-1 helicopter. (Bell Helicopter Textron Alert Service Bulletin 206L-94-94 Revision A dated 11 July 1994 refers.)\n\nNote: Transport Canada AD CF-96-13 also refers.\n\nCompliance: Within 100 hours time in service after 7 November 1996, but not later than 28 February 1997.\n\nBackground: Transport Canada has advised that during engine starts with a depleted battery, the Kratos TOT indicators listed above, can display an erroneous low temperature. The erroneous low temperature indications can result in an overtemperature condition of the engine turbine and subsequent thermal damage to engine components.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific defective component. It has not expanded beyond its original purpose of mandating replacement of faulty Kratos TOT indicators in Bell 206L-1 helicopters."},"complexity_factors":["Single, unambiguous requirement with no conditional logic or exceptions","Only 2 specific part numbers affected, clearly identified","Single aircraft model variant specified (Bell 206L-1)","Straightforward compliance deadline (100 hours or fixed date)","No defined terms section, no cross-references to other legislation beyond a single referenced service bulletin","Total length: approximately 150 words of operative text"],"plain_english_summary":"This CASA Airworthiness Directive mandates replacement of faulty Kratos Turbine Outlet Temperature (TOT) gauges (P/N 124.444‑6 and 124.444‑20) installed on Bell Model 206L‑1 helicopters. The gauges can display falsely low temperatures after a weak/flat battery start, risking engine thermal damage or failure.\n\nOwners, operators and maintenance personnel must remove and replace the affected gauges with an approved alternative within the specified compliance window (100 flight hours after 7 Nov 1996 or by 28 Feb 1997)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with its stated corrective aim: replace the specified Kratos TOT indicators on Bell 206L-1 helicopters to mitigate erroneous low readings that could mask turbine overtemperature. It does not broaden affected models, additional parts, or further actions beyond the specified replacement and compliance timeframe; it relies on the Bell service bulletin and Transport Canada AD for context."},"complexity_factors":["Narrow applicability to a single helicopter model (Bell 206L-1)","Specific parts identified by part numbers (P/N 124.444-6 and 124.444-20)","Single, straightforward corrective action (remove and replace with an approved unit)","Defined compliance window (100 hours from 7 Nov 1996; must be done by 28 Feb 1997)","Requirement to use any TOT indicator \"approved for use\" introduces administrative approval/parts-compatibility checks","Cross-reference to manufacturer service bulletin and Transport Canada AD (coordination and traceability considerations)","Safety-critical operational consequence (risk of engine overtemperature) but no complex inspection or diagnostic regime"],"plain_english_summary":"This airworthiness directive requires removal of Kratos turbine outlet temperature (TOT) indicators P/N 124.444-6 and 124.444-20 from Bell Model 206L-1 helicopters and replacement with any other TOT indicator approved for that helicopter. Compliance is within 100 hours time in service after 7 November 1996 but not later than 28 February 1997.\n\nThe directive responds to reports that, when engines are started with a depleted battery, the listed indicators can show erroneously low temperatures, which may conceal real overtemperature and lead to thermal engine damage."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-138-turbine-outlet-temperature-indicator","history":"/api/acts/ad-bell-206-138-turbine-outlet-temperature-indicator/history","analysis":"/api/acts/ad-bell-206-138-turbine-outlet-temperature-indicator/analysis","conflicts":"/api/acts/ad-bell-206-138-turbine-outlet-temperature-indicator/conflicts","importantCases":"/api/acts/ad-bell-206-138-turbine-outlet-temperature-indicator/important-cases","documents":"/api/acts/ad-bell-206-138-turbine-outlet-temperature-indicator/documents"}}