{"id":"F2006B02272","name":"AD/AL 250/61 Amdt 3 - Gas Producer Turbine Assembly and Second Stage Nozzle Seal","slug":"ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41502,"registerId":"commonwealth-F2006B02272-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/61 Amdt 3 - Gas Producer Turbine Assembly and Second Stage Nozzle Seal","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 250/61\n\nAmdt 3\n\n  \n\nGas Producer Turbine Assembly and Second Stage Nozzle Seal\n\n  \n8/88\n\nApplicability: All 250-C30/C30S engines installed in or intended for installation in Sikorsky S-76 aircraft and/or all C30 series engines with serial numbers listed in the Requirement Document.\n\nRequirement: 1. Inspect second stage turbine 29-34 labyrinth seal for rub in accordance with Allison CEB-A-72-3127R.3.\n\nFAA AD 84-17-51 R1 Amendment 39-4963 refers to the original and Revision 1 of the Requirement Document.\n\n2. Increase second stage nozzle 29-34 labyrinth seal clearance in accordance with Allison CEB-A-72-3131, Rev.1.\n\nCompliance: Part 1 above: Applicable engines having 100 hours or less time in service since gas producer turbine rotor assembly overhaul, repair or disassembly. Inspect the second stage turbine nozzle interstage seal for evidence of rub within the next 50 hours’ time in service after 5 September 1984.\n\nPart 2 above:\n\n    (i) For engines assembled in accordance with CEB-A-72-3127 Revision 1 concurrent with inspection detailed in Part 1 above.\n\n    (ii) For engines assembled in accordance with CEB-A-72-3127 or Allison Message THO-1977W-RMG-84 unless already accomplished no later than the next overhaul certified after 28 February 1985.\n\nCompliance with a previous issue of this Directive constitutes compliance with this amendment.\n\nBackground: Amendment 3 to this Directive reflects the latest revision to CEB-A-72-3127.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Amendment 3 updates the referenced Allison requirement document (Background) and restates inspection and clearance tasks (Requirement), but does not broaden the directive's applicability or add new engine categories. Existing compliance actions under earlier issues remain acceptable (Compliance)."},"complexity_factors":["Technical specificity: requires inspection and dimensional change to a turbine labyrinth seal (Requirement 1–2).","Cross‑references to external service documents and FAA ADs (Allison CEB‑A‑72‑3127/3131, FAA AD 84‑17‑51 R1).","Time‑bound compliance windows tied to hours‑in‑service and next overhaul dates (Compliance).","Limited applicability by engine model, aircraft type and listed serial numbers (Applicability).","Allowance that prior compliance with earlier Directive issues satisfies the amendment (Compliance)."],"plain_english_summary":"This airworthiness directive requires inspection and corrective action on the second‑stage turbine labyrinth seal of certain Allison 250‑C30/C30S engines (Sikorsky S‑76 installations and serial‑numbered C30 engines listed in the Requirement Document). Operators and maintenance organisations must inspect for rub and, where specified, increase the seal clearance within the stated service‑hour and overhaul windows (Requirement 1–2; Compliance). The amendment updates the referenced Allison service documents; owners/operators pay for inspections and any repairs or clearance changes and must schedule work to meet the prescribed deadlines."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 3 to an existing Airworthiness Directive. The amendment simply updates the referenced technical document to its latest revision (CEB-A-72-3127R.3). The scope remains unchanged—same engines, same safety issue, same basic requirements. The amendment includes a savings clause confirming compliance with previous versions still counts."},"complexity_factors":["Multiple compliance deadlines based on engine history and assembly method (3 different pathways in Part 2)","Cross-references to external technical documents (Allison CEB-A-72-3127R.3, CEB-A-72-3131 Rev.1, FAA AD 84-17-51 R1)","Specific applicability criteria combining aircraft type, engine model, and serial number lists","Conditional language ('unless already accomplished', 'concurrent with')","Technical aviation terminology requiring domain knowledge (labyrinth seals, time in service, gas producer turbine assembly)"],"plain_english_summary":"This airworthiness directive requires owners/operators of Sikorsky S‑76 helicopters with Allison 250‑C30/C30S engines (and specified serial numbers) to inspect the second‑stage turbine 29‑34 labyrinth seal for rubbing damage and to increase the seal clearance to prevent recurrence.  \n\nThe actions prevent rubbing‑induced engine damage and potential in‑flight failure; inspection is due within 50 flight hours after 5 Sep 1984 for low‑hour engines, and modification by the next overhaul after 28 Feb 1985. Prior compliance satisfies the requirement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal","history":"/api/acts/ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal/history","analysis":"/api/acts/ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal/analysis","conflicts":"/api/acts/ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal/conflicts","importantCases":"/api/acts/ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal/important-cases","documents":"/api/acts/ad-al-250-61-amdt-3-gas-producer-turbine-assembly-and-second-stage-nozzle-seal/documents"}}