{"id":"F2006B07404","name":"AD/TFE 731/24 - First and Second Stage Low Pressure Turbine Discs","slug":"ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49621,"registerId":"commonwealth-F2006B07404-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TFE 731/24 - First and Second Stage Low Pressure Turbine Discs","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAlliedSignal (Garrett/AiResearch) Turbine Engines \\- TFE731 Series\n\nAD/TFE731/24 First and Second Stage Low Pressure Turbine Discs\n\n  \n1/94\n\nApplicability: 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 TFE731-A72-3544.\n\nRequirement: Remove first and second stage low pressure turbine discs in accordance with Allied Signal Aerospace Service Bulletin TFE731-A72-3544.\n\nCompliance: Effective 6 January 1994; Within 100 hours time in service or at next access to affected parts, whichever occurs first.\n\nBackground: This Directive requires the removal from service of certain first and second stage low pressure turbine discs. The requirement follows advice, certain first and second stage discs may have been subjected to incorrect heat treatment during the manufacturing process.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1763},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is the original issuance of the directive, maintaining its narrow, targeted scope addressing only the specific manufacturing defect (incorrect heat treatment) in identified turbine discs. It does not expand beyond the initial safety concern."},"complexity_factors":["Relies on external technical service bulletin (TFE731-A72-3544) for critical details including serial numbers and removal procedures","Requires specialized aviation knowledge to identify 'first stage' and 'second stage' low pressure turbine components","Dual-threshold compliance condition ('whichever occurs first' between flight hours and maintenance access)","Dependency on manufacturer-specific serial number tables not reproduced in the directive text"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of AlliedSignal TFE731-2 and TFE731-3 engines with certain serial-numbered first or second stage low-pressure turbine discs (as listed in Service Bulletin TFE731-A72-3544) to remove those discs from service.  \n\nEffective 6 Jan 1994, compliance was required within 100 flight hours or at the next maintenance access; the action prevents failures from discs potentially weakened by incorrect heat treatment that could lead to engine accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs","history":"/api/acts/ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs/history","analysis":"/api/acts/ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs/analysis","conflicts":"/api/acts/ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs/conflicts","importantCases":"/api/acts/ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs/important-cases","documents":"/api/acts/ad-tfe-731-24-first-and-second-stage-low-pressure-turbine-discs/documents"}}