{"id":"F2006B07403","name":"AD/TFE 731/22 - Low Pressure Turbine Third Stage Disc Material Anomalies","slug":"ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49618,"registerId":"commonwealth-F2006B07403-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TFE 731/22 - Low Pressure Turbine Third Stage Disc Material Anomalies","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/TFE731/22 Low Pressure Turbine Third Stage\n\nDisc Material Anomalies\n\n  \n3/93 DM\n\nApplicability: Garrett Engine Models TFE731-2, \\-3,-3A,-3AR and \\-3R equipped with Part Number 3072068-X, 3072544-X, 3073015-X, or 3073115-X low pressure turbine rotor discs identified by the serial numbers listed in the Allied-Signal Aerospace Company Garrett Engine Division Alert Service Bulletin TFE731-A72-3474 dated 3 April 1992.\n\nRequirement: Action in accordance with the requirements of the Allied-Signal Aerospace Company Garrett Engine Division Alert Service Bulletin TFE731-A72-3474 dated 3 April 1992.\n\nNote: FAA AD 92-21-06 refers.\n\nCompliance: At the next access to the turbine rotor assembly or before accumulating 50 hours time in service after 25 January 1993.\n\nBackground: Investigation into a turbine hub and disc failure in an Auxiliary Power Unit revealed random oxide inclusions in a heat lot from which a number of Low Pressure Turbine discs for TFE731-2 and -3 series engines was manufactured. An examination of some rotor discs manufactured from this heat lot material revealed that these anomalies had caused cracking in a significant number of them which could could lead to uncontained engine failure. The requirement document service bulletin identifies items made from the heat lot by serial number, and it gives procedures for their removal and replacement.","sortOrder":0}],"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 is a discrete, targeted safety directive addressing a specific manufacturing defect in specific engine models. It has not expanded beyond its original purpose of addressing the heat lot material anomaly identified in 1992."},"complexity_factors":["Single, specific mechanical issue with clearly identified part numbers and serial numbers","Only 4 part number ranges to check against","Straightforward compliance deadline (next maintenance access OR 50 hours after fixed date)","Single reference document (AlliedSignal Service Bulletin TFE731-A72-3474)","No nested exceptions, conditional logic, or alternative compliance methods","Short document (approximately 250 words)","Only one defined term implicitly used ('time in service' — standard aviation term meaning flight hours)"],"plain_english_summary":"This CASA Airworthiness Directive legally requires owners/operators of Garrett TFE731-2, -3, -3A, -3AR and -3R engines to check for and replace certain low-pressure turbine discs made from a 1992 batch with oxide inclusions that have caused cracking and risk uncontained engine failure. Affected part numbers and specific serial numbers are listed in the manufacturer’s April 1992 service bulletin.\n\nDiscs must be removed and replaced per Service Bulletin TFE731-A72-3474 at the next turbine access or before accruing 50 flight hours after 25 January 1993, whichever comes first."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive targets a defined set of turbine discs from a specific heat lot and mandates their removal/replacement per the manufacturer service bulletin to address material anomalies. It does not expand regulatory scope beyond addressing those identified discs."},"complexity_factors":["Narrow applicability to specific engine models and to discs identified by part and serial numbers (identification burden on operators).","Primary compliance action is defined by an external Allied‑Signal Alert Service Bulletin (dependency on manufacturer document).","Short compliance window (next rotor access or within 50 flight hours of a fixed date) increases logistical urgency for operators and maintenance providers.","Safety-critical nature (risk of uncontained engine failure) raises regulatory enforcement and scheduling priority.","Cross-reference to FAA AD 92-21-06 and placement within CASA Part 39 creates coordination across authorities.","Potential supply and replacement part availability not addressed in the directive (implementation and cost uncertainty)."],"plain_english_summary":"This directive requires owners/operators of Garrett TFE731-2 and -3 series engines fitted with certain low-pressure turbine third-stage discs (specific part and serial numbers listed in the Allied‑Signal alert service bulletin) to follow that bulletin's removal and replacement procedures because oxide inclusions in a manufacturing heat lot have caused cracking. Compliance is required at the next access to the turbine rotor assembly or within 50 hours after 25 January 1993; operators bear inspection, removal and replacement costs and must schedule maintenance accordingly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies","history":"/api/acts/ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies/history","analysis":"/api/acts/ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies/analysis","conflicts":"/api/acts/ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies/conflicts","importantCases":"/api/acts/ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies/important-cases","documents":"/api/acts/ad-tfe-731-22-low-pressure-turbine-third-stage-disc-material-anomalies/documents"}}