{"id":"F2021L01408","name":"AD/AL 250/64 Amdt 4 Internal Energy Absorbing Ring","slug":"ad-al-250-64-amdt-4-internal-energy-absorbing-ring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":102121,"registerId":"commonwealth-F2021L01408-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 250/64 Amdt 4 | Internal Energy Absorbing Ring | 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 an internal energy absorbing ring in accordance with Rolls Royce (Allison) Alert Service Bulletin (ASB) CEB-A-72-3128 R1, Para 2 Accomplishment Instructions, as in force on the date of commencement of this AD.Note 1: This AD may be carried out in conjunction with AD/AL 250/66 Amdt 3.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 3 of this AD was amended to rationalize previous requirements, and to increase the engine models and aircraft applicable. The Requirements now require the subject internal energy absorbing ring to be installed in all 250-C30 series engines. Previous references to airframe mounted, external containment shields and the Allison Assured Engine configuration were deleted.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 250/64 Amdt 4","sectionType":"part","heading":"AD/AL 250/64 Amdt 4","content":"## AD/AL 250/64 Amdt 4","sortOrder":1},{"sectionNumber":"Internal Energy Absorbing Ring","sectionType":"part","heading":"Internal Energy Absorbing Ring","content":"## Internal Energy Absorbing Ring","sortOrder":2},{"sectionNumber":"20/2021","sectionType":"part","heading":"20/2021","content":"## 20/2021","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment broadened the scope by requiring the internal energy‑absorbing ring to be installed in all 250‑C30 series engines and by deleting previous references to airframe-mounted external containment shields, the Allison Assured Engine configuration, and Civil Aviation Order 106. The change centralises the mitigation on the internal ring and removes prior alternative measures."},"complexity_factors":["Narrow technical scope: applies only to specific engine models (250‑C30 series), reducing breadth of stakeholders.","Mandated compliance with an external manufacturer Alert Service Bulletin (CEB‑A‑72‑3128 R1) — requires access to and reliance on a separate technical document for exact steps.","Short statutory compliance window (30 days from commencement) — increases scheduling and operational burden for operators and installers.","Cross‑references to other safety directives (may be carried out with AD/AL 250/66 Amdt 3; based on FAA AD 86‑19‑12) — creates interdependence between regulatory instruments.","Removal of prior mitigation options (external containment shields and Allison Assured Engine configuration) — concentrates compliance on a single engineering solution.","Limited procedural detail in the AD itself — execution discretion rests with maintenance providers following the cited service bulletin."],"plain_english_summary":"This AD requires operators of Rolls Royce (Allison) 250‑C30 series turbine engines to fit an internal energy‑absorbing ring in accordance with Rolls Royce (Allison) Alert Service Bulletin CEB‑A‑72‑3128 R1 (para 2), within 30 days of the AD’s commencement (8 October 2021). Operators pay for and schedule the modification; the regulator enforces compliance. The amendment expands mandatory fitment across all 250‑C30 variants and removes prior references to external containment shields and other alternative configurations."},"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":"This amendment has narrowed and clarified the scope compared to earlier versions. Amendment 3 had expanded coverage to include external containment shields and airframe-mounted configurations. Amendment 4 removes those broader elements, deletes references to 'Allison Assured Engine configuration,' and focuses solely on the internal energy absorbing ring for C30 series engines. It also strips out references to Civil Aviation Order 106, indicating a shift toward modern regulatory simplification."},"complexity_factors":["Single, unambiguous requirement: install one specific component per one referenced technical document","No defined terms section — all terminology is standard aviation maintenance language","Minimal conditional logic: only one exception ('unless previously accomplished')","No cross-references to other legislation except a helpful note about related directive AD/AL 250/66 Amdt 3","Extremely short — approximately 150 words of substantive content","Clear applicability table listing specific engine models by exact designation"],"plain_english_summary":"This AD mandates that owners/operators of Rolls‑Royce (Allison) 250‑C30 series turbine engines install an internal energy‑absorbing ring per Rolls‑Royce ASB CEB‑A‑72‑3128 R1 to contain high‑energy debris from catastrophic failures. \n\nIt affects all aircraft fitted with 250‑C30, ‑C30L, ‑C30M, ‑C30P and ‑C30S engines, must be done within 30 days of 8 Oct 2021, and replaces older shield requirements to simplify compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-64-amdt-4-internal-energy-absorbing-ring","history":"/api/acts/ad-al-250-64-amdt-4-internal-energy-absorbing-ring/history","analysis":"/api/acts/ad-al-250-64-amdt-4-internal-energy-absorbing-ring/analysis","conflicts":"/api/acts/ad-al-250-64-amdt-4-internal-energy-absorbing-ring/conflicts","importantCases":"/api/acts/ad-al-250-64-amdt-4-internal-energy-absorbing-ring/important-cases","documents":"/api/acts/ad-al-250-64-amdt-4-internal-energy-absorbing-ring/documents"}}