{"id":"F2010L00089","name":"AD/TFE731/24 Amdt 1 - First and Second Stage Low Pressure Turbine Discs","slug":"ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":122783,"registerId":"commonwealth-F2010L00089-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AlliedSignal (Garrett/AiResearch) Turbin","sectionType":"division","heading":"AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series","content":"### AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series\n\n| AD/TFE731/24Amdt 1 | First and Second Stage LowPressure Turbine Discs | 1/2010 |\n| ------------------ | ------------------------------------------------ | ------ |\n\n| Applicability: | TFE731-2 and -3 series engines fitted with first and/or second stage low pressure turbine discs as listed by serial number in Table 1 of Allied Signal Aerospace Service Bulletin (ASB) TFE731-A72-3544.                                                                                                                                                                                                                                                                                                                                 |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Remove first and second stage low pressure turbine discs in accordance with Allied Signal Aerospace ASB TFE731-A72-3544.Note: FAA AD 95-07-02 refers.                                                                                                                                                                                                                                                                                                                                                                                    |\n| Compliance:    | Unless already accomplished in accordance with the previous issue of this Directive, within 100 hours time-in-service (TIS) after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                  |\n|                | This Amendment becomes effective on 22 January 2010.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| Background:    | This Directive requires the removal from service of certain first and second stage low pressure turbine discs. The requirement follows advice that certain first and second stage discs may have been subjected to incorrect heat treatment during the manufacturing process.This amendment references the applicable State of design Directive which is also applicable to AD/TFE731/26 Amdt 1. For information, AD/TFE731/34 is also applicable to first and second stage low pressure turbine discs, but unrelated to this Directive. |\n\n![](image.001.png)\n\nMike Higgins  \nDelegate of the Civil Aviation Safety Authority\n\n4 January 2010","sortOrder":0},{"sectionNumber":"AD/TFE731/24Amdt 1","sectionType":"part","heading":"AD/TFE731/24Amdt 1","content":"## AD/TFE731/24Amdt 1","sortOrder":1},{"sectionNumber":"First and Second Stage LowPressure Turbi","sectionType":"part","heading":"First and Second Stage LowPressure Turbine Discs","content":"## First and Second Stage Low  \nPressure Turbine Discs","sortOrder":2},{"sectionNumber":"1/2010","sectionType":"part","heading":"1/2010","content":"## 1/2010","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope of AD/TFE731/24. It updates the reference to the manufacturer's service bulletin and clarifies the relationship to other related directives, but does not expand the safety issue or add new requirements beyond the original directive's purpose of removing defective turbine discs."},"complexity_factors":["Short, single-purpose directive with one clear requirement","Only 4 defined elements: applicability, requirement, compliance, and background","Single cross-reference to manufacturer service bulletin (ASB TFE731-A72-3544)","Simple conditional: compliance required 'unless already accomplished' under previous version","No nested exceptions or complex procedural steps","Heavy reliance on external technical document (service bulletin) for serial number identification"],"plain_english_summary":"This CASA Airworthiness Directive mandates removal from service of certain first- and second-stage low-pressure turbine discs in AlliedSignal (Garrett/AiResearch) TFE731-2 and TFE731-3 engines because of possible incorrect heat treatment that could cause catastrophic failure. \n\nIt affects operators and maintenance organizations using those engines, requires compliance within 100 flight hours from 22 January 2010, and amends the prior AD to align references with the FAA service bulletin/AD."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This instrument is an amendment to a prior Directive and restates a mandatory removal requirement while specifying a 100‑hour compliance window and updated cross-references to the State-of-design directive and FAA AD (Compliance; Background). The affected population remains limited to the serial-numbered first- and second-stage discs on TFE731-2 and -3 engines listed in the manufacturer's Service Bulletin; the amendment updates timing and cross-referencing rather than broadening engine applicability."},"complexity_factors":["Serial-numbered applicability requiring cross-check against Table 1 of ASB TFE731-A72-3544 (Applicability).","Mandatory removal action tied to manufacturer's Service Bulletin for procedures (Requirement).","Short compliance window of 100 hours time-in-service imposes operational scheduling pressure (Compliance).","Technical root cause (incorrect heat treatment) requires part replacement or specific engineering action, not just inspection (Background).","Cross-references to FAA AD 95-07-02 and other Commonwealth ADs increase compliance tracking and record-keeping (Requirement; Background).","This instrument is an amendment referring to prior Directive work—implementers must reconcile prior and current directives to confirm completion (Compliance; Background)."],"plain_english_summary":"This airworthiness amendment orders the removal from service of specific first- and second-stage low-pressure turbine discs on AlliedSignal TFE731-2 and -3 engines listed by serial number in the manufacturer's Service Bulletin, because those discs may have received incorrect heat treatment (Applicability; Requirement; Background). Operators and owners must remove affected parts within 100 hours time-in-service after the effective date unless already done, so operators bear the cost and scheduling burden and the regulator (CASA) enforces compliance (Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs","history":"/api/acts/ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs/history","analysis":"/api/acts/ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs/analysis","conflicts":"/api/acts/ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs/conflicts","importantCases":"/api/acts/ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs/important-cases","documents":"/api/acts/ad-tfe731-24-amdt-1-first-and-second-stage-low-pressure-turbine-discs/documents"}}