{"id":"F2006B11016","name":"AD/JT9D/23 - First Stage High Pressure Turbine Airseal","slug":"ad-jt9d-23-first-stage-high-pressure-turbine-airseal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56617,"registerId":"commonwealth-F2006B11016-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JT9D/23 - First Stage High Pressure Turbine Airseal","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)  \nPratt and Whitney Turbine Engines \\- JT9D Series\n\nAD/JT9D/23 First Stage High Pressure Turbine Airseal 2/91\n\nApplicability: JT9D-7R4D, \\-7R4D1, \\-7R4E, \\-7R4E1, \\-7R4E4, \\-7R4H1, \\-7R4G2, engines fitted with P/N 797576, 797576P48, 793707, 793707P48 first stage turbine airseals.\n\nRequirement: 1. Replace first stage high pressure turbine airseals as listed by serial number in PWA SB No JT9D-7R4-72-393 Rev 1, Para 2, Part A.\n\n2. Inspect, first stage high pressure turbine airseals not listed by serial in PWA SB No JT9D-7R4-72-393 Rev 1, Para 2, Part A, in accordance with PWA SB No JT9D- 7R4-72-393 Rev 1, Para 2, Part B.\n\nNote: FAA AD 90-23-19 refers.\n\nCompliance: 1. At next engine shop visit regardless of planned maintenance action or reason for engine removal.\n\n2. At next access to affected parts.\n\nBackground: This Directive reflects advice of an uncontained JT9D-7R4H1 engine failure event.\n\nThe failure was attributed to cracking of an Inconel-718 material airseal. Certain lower rated JT9D models may also be fitted with the same part number airseal. This Directive requires replacement or inspection of those airseals.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD remains tightly focused on its original purpose: addressing a specific material defect in a defined set of engine airseals following a known failure event. No scope creep is evident."},"complexity_factors":["Single, specific mechanical issue (one component in one engine series)","Only 8 engine models affected, clearly listed","Binary compliance path: replace if on list, inspect if not","Only 4 part numbers specified","No nested definitions or cross-referenced legislation","Clear compliance deadlines ('next shop visit', 'next access')","Single referenced technical document (PWA SB No JT9D-7R4-72-393 Rev 1)"],"plain_english_summary":"This CASA Airworthiness Directive legally requires operators of Pratt & Whitney JT9D-7R4 series engines to address cracked Inconel‑718 high‑pressure turbine airseals that caused an uncontained engine failure. Operators with airseals on the affected serial‑number list must replace them at the next engine shop visit; others must inspect per Pratt & Whitney’s service bulletin at the next access. It prevents catastrophic shrapnel risk and aligns with the FAA’s related AD."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive targets specific P/Ns and serial-numbered first-stage airseals on listed JT9D variants to address the cracking/uncontained-failure risk. It does not broaden applicability beyond those listed parts and similarly fitted lower-rated models, and mandates action at the next shop visit or access per the service bulletin."},"complexity_factors":["Technical specificity: exact part numbers and serial-number lists determine applicability.","Reliance on an external PWA Service Bulletin for procedures and serial-number identification.","Compliance timing tied to variable operational events (next shop visit / next access).","Record-keeping and parts-traceability required to identify affected engines and airseals.","Operational planning impact: coordinating shop visits and parts availability.","Decision point between replacement and inspection for non-listed serials.","Cross-reference to FAA AD introduces coordination with international regulatory guidance."],"plain_english_summary":"This AD requires replacement or inspection of specified first-stage high-pressure turbine airseals on Pratt & Whitney JT9D engines after cracking caused an uncontained engine failure.\n\nengine owners/operators must arrange replacement at the next engine shop visit or inspection at next access, incurring maintenance and shop costs. It affects operators of listed JT9D variants fitted with those part numbers and requires compliance with the cited PWA service bulletin's serial-number replacement and inspection procedures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jt9d-23-first-stage-high-pressure-turbine-airseal","history":"/api/acts/ad-jt9d-23-first-stage-high-pressure-turbine-airseal/history","analysis":"/api/acts/ad-jt9d-23-first-stage-high-pressure-turbine-airseal/analysis","conflicts":"/api/acts/ad-jt9d-23-first-stage-high-pressure-turbine-airseal/conflicts","importantCases":"/api/acts/ad-jt9d-23-first-stage-high-pressure-turbine-airseal/important-cases","documents":"/api/acts/ad-jt9d-23-first-stage-high-pressure-turbine-airseal/documents"}}