{"id":"F2006B02273","name":"AD/AL 250/62 Amdt 1 - Fourth Stage Nozzle Assembly - Replacement","slug":"ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41503,"registerId":"commonwealth-F2006B02273-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/62 Amdt 1 - Fourth Stage Nozzle Assembly - Replacement","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)  \nAllison Turbine Engines \\- 250 Series\n\nAD/AL 250/62\n\nAmdt 1\n\n  \nFourth Stage Nozzle Assembly \\- Replacement 7/85\n\nApplicability: All model 250-C30, C30 (Hughes), C30P and C30S with serial numbers as listed in the requirement document and, turbine assemblies incorporating P/N 23008470 or 6898694 fourth stage nozzle assy.\n\nRequirement: Allison 250-C30 series CEB-A-72-3122 Rev.1.\n\nCompliance: Prior to completion of the next overhaul after 31 December 1984 or on the next occasion the power turbine is disassembled.\n\nBackground: This directive is amended to reflect the manufacturers CEB-72-3122 Rev 1 which revises affectivity, changes rework dimensions, and adds the latest nozzle part number and references.\n\nThere have been instances of rubbing contact between the third stage turbine wheel and the inner band of the fourth stage nozzle.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":4056},"content_quality":"ok","complexity_score":4,"rejection_reason":"","scope_assessment":{"changed":true,"description":"This amendment expands the scope of the original directive by revising which engines are covered (affectivity), adding a new nozzle part number to the requirements, and updating rework dimensions. It broadens applicability beyond the original AD/AL 250/62."},"complexity_factors":["Cross-reference to external technical manual (Allison CEB-A-72-3122 Rev.1) not reproduced in the directive","Requires precise identification of engine serial numbers and specific part numbers (P/N 23008470 or 6898694)","Technical aviation terminology requiring specialized engineering knowledge (turbine wheel, nozzle assembly, power turbine)","Conditional compliance deadline with two alternative triggering events (overhaul vs disassembly)"],"plain_english_summary":"This mandatory CASA Airworthiness Directive requires owners/operators of Allison 250‑C30 series engines (including C30P/C30S variants with listed serials, or engines fitted with 4th‑stage nozzle P/N 23008470 or 6898694) to replace or rework the 4th‑stage nozzle assembly per Allison CEB‑A‑72‑3122 Rev 1. It prevents 3rd‑stage turbine rubbing that can damage the engine and cause in‑flight failure. Compliance is due by the next overhaul after 31 Dec 1984 or at the next power‑turbine disassembly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement","history":"/api/acts/ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement/history","analysis":"/api/acts/ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement/analysis","conflicts":"/api/acts/ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement/conflicts","importantCases":"/api/acts/ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement/important-cases","documents":"/api/acts/ad-al-250-62-amdt-1-fourth-stage-nozzle-assembly-replacement/documents"}}