{"id":"F2006B08709","name":"AD/DART/23 Amdt 1 - Low Pressure Turbine Disc","slug":"ad-dart-23-amdt-1-low-pressure-turbine-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51900,"registerId":"commonwealth-F2006B08709-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DART/23 Amdt 1 - Low Pressure Turbine Disc","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Safety Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/DART/23 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nRolls Royce Turbine Engines \\- Dart Series\n\nAD/DART/23\n\nAmdt 1\n\n  \nLow Pressure Turbine Disc 10/2003\n\nApplicability: Dart 520, 525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536, 542, 543, 550\n\nand 552 series engines.\n\nRequirement: Action in accordance with Rolls Royce Alert Service Bulletin (ASB) Da72-A512.\n\nThis Directive supersedes the requirements of AD/ENG/7 with respect to Low Pressure Turbine (LPT) disc lives for the applicable Rolls Royce Dart series engines.\n\nCompliance: As detailed in the Requirement document.\n\nThis Amendment becomes effective on 2 October 2003.\n\nBackground: The original issue of this Directive was raised to limit the cyclic lives of certain LPT discs following advice that four LPT disc failure events had occurred in-service between 1985 and 1989. This Amendment does not alter the technical requirements of this Directive but replaces reference to cancelled AD/DART/1 with AD/GEN/7 together with minor editorial changes.\n\nThe original issue of this Airworthiness Directive became effective on 5 October 1989.\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 19 August 2003\n\n![](image.001.png)\n\nThe above AD is notified in the Commonwealth of Australia Gazette on 10 September 2003.\n\n  \n\nPage 1 of 1","sortOrder":0}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope has not changed: the Amendment does not alter the technical requirements governing LPT disc lives but updates cross-references and makes minor editorial changes. The directive continues to require compliance with Rolls Royce ASB Da72-A512 for the listed engines (Background; Requirement)."},"complexity_factors":["Dependence on an external manufacturer document (Rolls Royce ASB Da72-A512) for technical detail and compliance timing, requiring operators to obtain and follow that bulletin (Requirement; Compliance).","Applicability spans multiple engine models (Dart 520–552), increasing the number of affected operators and fleet-level planning (Applicability).","Compliance language delegates timing and specific actions to the ASB rather than stating them in the AD, creating operational ambiguity until the ASB is consulted (Compliance; Requirement).","Legal layering: this Amendment revokes and supersedes prior ADs and updates cross-references (revokes AD/DART/23; replaces reference to cancelled AD/DART/1 with AD/GEN/7), so operators must track which AD version governs their obligations (Background).","No new technical requirements introduced, so complexity is administrative rather than engineering; however, enforcement under CASR subregulation 39.1(1) gives CASA discretion to require corrective action (Background; Requirement)."],"plain_english_summary":"This amendment reissues an Airworthiness Directive requiring operators of listed Rolls‑Royce Dart series engines to follow Rolls‑Royce Alert Service Bulletin Da72‑A512 to limit the cyclic lives of certain low pressure turbine (LPT) discs. It applies to Dart 520–552 engines and took effect on 2 October 2003. CASA (delegate) enforces the requirement; operators must carry out inspections or replacements per the ASB and therefore bear the direct costs and scheduling burden (Requirement; Applicability; Compliance; Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment explicitly states it makes no technical changes to the original 1989 directive. The scope remains exactly as originally intended: limiting LPT disc cyclic lives for safety reasons. The only changes are administrative — updating references to other directives that have been cancelled or renumbered."},"complexity_factors":["Single-page document with straightforward structure (Applicability, Requirement, Compliance, Background)","Only one substantive requirement: comply with an external Rolls-Royce service bulletin","No defined terms section — relies on standard aviation terminology","No nested exceptions or conditional logic beyond the applicability list","Minimal cross-referencing (only references to superseded directives AD/ENG/7 and AD/DART/1, and replacement with AD/GEN/7)","Clear, linear compliance instruction ('As detailed in the Requirement document')"],"plain_english_summary":"This CASA Airworthiness Directive mandates life limits and required inspection/replacement of Low Pressure Turbine (LPT) discs on Rolls‑Royce Dart 520–552 engines—commonly in Fokker F27 and some HS 748 aircraft—to prevent catastrophic in‑flight disc failures. \n\nThe October 2003 amendment only updates paperwork references and editorial details; it does not change the original 1989 safety requirements or the Rolls‑Royce maintenance instructions."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dart-23-amdt-1-low-pressure-turbine-disc","history":"/api/acts/ad-dart-23-amdt-1-low-pressure-turbine-disc/history","analysis":"/api/acts/ad-dart-23-amdt-1-low-pressure-turbine-disc/analysis","conflicts":"/api/acts/ad-dart-23-amdt-1-low-pressure-turbine-disc/conflicts","importantCases":"/api/acts/ad-dart-23-amdt-1-low-pressure-turbine-disc/important-cases","documents":"/api/acts/ad-dart-23-amdt-1-low-pressure-turbine-disc/documents"}}