{"id":"F2021L01403","name":"AD/AL 250/66 Amdt 3 Second Stage Turbine Wheel","slug":"ad-al-250-66-amdt-3-second-stage-turbine-wheel","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":102117,"registerId":"commonwealth-F2021L01403-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Rolls Royce (Allison) Turbine Engines - ","sectionType":"part","heading":"Rolls Royce (Allison) Turbine Engines - 250 Series","content":"# Rolls Royce (Allison) Turbine Engines - 250 Series\n\n| AD/AL 250/66 Amdt 3 | Second Stage Turbine Wheel | 20/2021 |\n| ------------------- | -------------------------- | ------- |\n\n| Applicability: | Rolls Royce (Allison) model 250-C30, 250-C30L, 250-C30M, 250-C30P, and 250‑C30S engines.                                                                                                                                                                                                                                                                                                                                                                |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Install a second stage turbine wheel part number (P/N) 23032280 in accordance with the requirements of Rolls Royce (Allison) Alert Service Bulletin (ASB) CEB‑A‑72‑3132, or CEB‑A‑72-3137 Rev.2, as applicable, as in force on the commencement date of this AD.Note 1: This AD may be carried out in conjunction with AD/AL 250/64 Amdt 4.Note 2: United States of America Federal Aviation Administration (FAA) AD 86‑19‑12 is the basis for this AD. |\n| Compliance:    | Unless previously accomplished; within 30 days after the commencement date of this AD.                                                                                                                                                                                                                                                                                                                                                                  |\n|                | This AD commences on 8 October 2021.                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| Background:    | Amendment 2 of this AD was amended to increase the engine models and helicopters affected. The requirement to install a higher burst speed second stage turbine wheel is now applicable to all C30 series engines, regardless of the type of helicopter to which the engine is fitted.This amendment removes reference to Civil Aviation Order (CAO) 106.                                                                                               |\n\n![Signature of Delegate](image.001.jpeg)\n\nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n29 September 2021","sortOrder":0},{"sectionNumber":"AD/AL 250/66 Amdt 3","sectionType":"part","heading":"AD/AL 250/66 Amdt 3","content":"## AD/AL 250/66 Amdt 3","sortOrder":1},{"sectionNumber":"Second Stage Turbine Wheel","sectionType":"part","heading":"Second Stage Turbine Wheel","content":"## Second Stage Turbine Wheel","sortOrder":2},{"sectionNumber":"20/2021","sectionType":"part","heading":"20/2021","content":"## 20/2021","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The amendment expanded applicability: Amendment 2 increased the engine models and helicopters affected and the current amendment makes the requirement applicable to all C30 series engines regardless of helicopter type. The amendment also removes reference to Civil Aviation Order 106, altering the regulatory references while maintaining the technical requirement to fit P/N 23032280 (Background)."},"complexity_factors":["Specific mandatory hardware change: installation of second stage turbine wheel P/N 23032280 (Requirement).","Cross-references to one of two Rolls Royce (Allison) Alert Service Bulletins (CEB‑A‑72‑3132 or CEB‑A‑72‑3137 Rev.2) — compliance depends on which ASB applies (Requirement).","Short, fixed compliance window of 30 days from commencement imposes scheduling and cost pressure on operators (Compliance).","Applicability covers multiple engine variants (250‑C30, C30L, C30M, C30P, C30S) and now 'all C30 series engines', expanding prior scope (Background).","Notes allow combined compliance with another AD (AD/AL 250/64 Amdt 4), creating interaction effects between directives (Requirement, Note 1).","Relies on an external foreign AD as legal basis (FAA AD 86‑19‑12), creating dependence on overseas findings (Requirement, Note 2).","Removal of a prior regulatory cross-reference (CAO 106) changes the legal framing without altering the technical requirement (Background).","Costs fall on engine operators/owners (parts and installation); regulator discretion is limited to mandating the part and ASB compliance within the stated timeframe (Requirement, Compliance)."],"plain_english_summary":"Requires operators of Rolls Royce (Allison) 250‑C30 series engines to install a higher‑burst‑speed second‑stage turbine wheel (P/N 23032280) in accordance with the manufacturer’s Alert Service Bulletin, within 30 days of this AD’s start date (8 Oct 2021). The AD applies to all C30 series engines, cites FAA AD 86‑19‑12 as its basis, and matters because it creates an immediate maintenance and compliance obligation for affected engine operators."},"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":2,"scope_assessment":{"changed":true,"description":"The original directive (implied by Amendment 2 background) was narrower, applying only to certain helicopter types. Amendment 3 confirms the requirement now applies to all C30 series engines regardless of helicopter type, representing a scope expansion from targeted to universal coverage for this engine series. Additionally, the removal of CAO 106 references modernises the regulatory framework without changing substantive requirements."},"complexity_factors":["Single, specific mechanical requirement (replace one part with one specific part number)","Only 5 engine models affected, clearly listed","Simple compliance deadline (30 days from commencement)","Two alternative technical documents permitted for compliance (ASB CEB-A-72-3132 or CEB-A-72-3137 Rev.2)","One cross-reference to related directive (AD/AL 250/64 Amdt 4) noted as optional conjunction","No nested conditions, exceptions, or defined terms section","Based on existing US FAA directive (AD 86-19-12), reducing interpretive complexity"],"plain_english_summary":"This CASA Airworthiness Directive mandates replacement of the second-stage turbine wheel in Rolls‑Royce (Allison) 250‑C30 series engines with a stronger part (p/n 23032280) per Rolls‑Royce Alert Service Bulletin, within 30 days. It affects owners, operators and maintenance organisations for any aircraft using these engines.\n\nThe change broadens coverage to all C30 engines (not just certain helicopter models) and removes an outdated regulatory reference."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-66-amdt-3-second-stage-turbine-wheel","history":"/api/acts/ad-al-250-66-amdt-3-second-stage-turbine-wheel/history","analysis":"/api/acts/ad-al-250-66-amdt-3-second-stage-turbine-wheel/analysis","conflicts":"/api/acts/ad-al-250-66-amdt-3-second-stage-turbine-wheel/conflicts","importantCases":"/api/acts/ad-al-250-66-amdt-3-second-stage-turbine-wheel/important-cases","documents":"/api/acts/ad-al-250-66-amdt-3-second-stage-turbine-wheel/documents"}}