{"id":"F2006B08715","name":"AD/DART/29 Amdt 2 - High Pressure Turbine Discs","slug":"ad-dart-29-amdt-2-high-pressure-turbine-discs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51913,"registerId":"commonwealth-F2006B08715-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DART/29 Amdt 2 - High Pressure Turbine Discs","content":"![](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/29 Amdt 1 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/29\n\nAmdt 2\n\n  \nHigh Pressure Turbine Discs 10/2003\n\nApplicability: Rolls Royce Dart series engines as detailed by model in Rolls Royce Service Bulletin (SB) Da72-533, Revision 2 and not incorporating modification 1946 (SB Da72-533).\n\nRequirement: 1. Replace or rework affected high pressure turbine (HPT) discs in accordance with the procedure detailed in Rolls Royce SB Da72-533 Revision 2; OR\n\n2. As considered appropriate by the operator, carry out a once-only inspection in accordance with Rolls Royce SB Da72-536. As provided in German LBA AD 2001-116/6 and Rolls Royce SB Da72-536 a satisfactory inspection result allows an extension to the interim compliance times of Rolls Royce SB Da72-533 of 750 flight cycles from the date of inspection but not beyond 30 June 2004. Such an extension to the interim compliance times of Rolls Royce SB Da72-533 may not be used unless a satisfactory inspection has been carried out in accordance with Rolls Royce SB Da72-536.\n\nNote: German LBA AD 2001-116/6 refers.\n\nCompliance: For Requirement 1: As detailed in the Requirement document.\n\nFor Requirement 2: As contained in the Requirement. This Amendment becomes effective on 2 October 2003.\n\nBackground: This Directive was originally issued to address in-service failures of HPT disc diaphragms that resulted in three events of the HPT disc release. The failures were attributed to 2D excitation of the HPT assembly as a result of frettage between HPT disc and Intermediate Pressure Turbine (IPT) disc seal arms. Amendment 1 was issued to reflect the manufacture’s latest revision to the requirement document that included, in part, a drawdown programme for HPT discs not incorporating modification 1946. This revision recognises German LBA AD 2001-116/6 as the authority document for the AD and thereby introduces an NDT inspection that if satisfactory provides for an extension to the compliance times contained in RR SB Da72-533.\n\nRolls Royce Turbine Engines \\- Dart Series\n\nAD/DART/29 Amdt 2 (continued)\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \nAmendment 1 of this Airworthiness Directive became effective on 4 October 2001. The original issue of this Airworthiness Directive became effective on 12 July 2001.\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.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The amendment does not broaden the set of affected engines (still Rolls‑Royce Dart engines without modification 1946) but alters compliance options. It incorporates the manufacturer's revised Service Bulletin and recognises German LBA AD 2001‑116/6, introducing a once‑only NDT inspection that—if satisfactory—permits a limited extension of interim compliance times (750 flight cycles, not beyond 30 June 2004). Thus the operational compliance regime was changed while the underlying safety scope remained the same."},"complexity_factors":["References multiple external technical documents (Rolls‑Royce SB Da72‑533 Rev 2; SB Da72‑536; German LBA AD 2001‑116/6) requiring cross‑checking","Conditional compliance paths (mandatory replace/rework OR optional once‑only NDT inspection enabling a limited extension)","Technical subject matter (high pressure turbine discs, frettage, NDT inspection) requiring specialist maintenance capability","Time‑limited relief (inspection can extend interim compliance by 750 flight cycles but not beyond 30 June 2004)","Applicability restriction to engines not incorporating modification 1946 — requires records checks","Regulatory delegation and cross‑reference to CASR subreg 39.1(1) and manufacturer authority documents","Operational impacts (maintenance planning, aircraft downtime and cost trade‑offs for operators)"],"plain_english_summary":"This airworthiness directive requires operators of Rolls‑Royce Dart series engines that do not incorporate modification 1946 to either replace or rework affected high pressure turbine (HPT) discs per Rolls‑Royce Service Bulletin Da72‑533 Rev 2, or perform a one‑off NDT inspection under SB Da72‑536 which can extend interim compliance by up to 750 flight cycles (but not beyond 30 June 2004).\n\nIt affects aircraft operators and maintenance providers, who must fund and carry out the work; the CASA delegate issues the requirement under CASR subreg 39.1(1). Decisions between immediate rework and inspection change maintenance scheduling, costs and aircraft downtime."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original directive (July 2001) was a straightforward safety order to address HPT disc failures. Amendment 1 (October 2001) added a drawdown programme. This Amendment 2 significantly expands the scope by incorporating a foreign aviation authority's directive (German LBA AD 2001-116/6) as an alternative compliance pathway, effectively creating a dual-track system with conditional extensions. The directive has evolved from a simple 'fix it by this date' order to a complex, conditional framework allowing negotiated timelines based on inspection outcomes."},"complexity_factors":["Multiple compliance pathways (Requirement 1 vs Requirement 2) with different conditions and deadlines","Cross-references to external technical documents: Rolls-Royce SB Da72-533 Rev 2, Rolls-Royce SB Da72-536, and German LBA AD 2001-116/6","Conditional logic: the 750 flight cycle extension is contingent on a 'satisfactory inspection result' and hard-capped at 30 June 2004","Exclusion criteria: engines with 'modification 1946' are exempt, requiring operators to check their engine records","Nested effective dates: Amendment 2 becomes effective 2 October 2003, but references back to Amendment 1 (4 October 2001) and original issue (12 July 2001)","Technical aviation terminology requiring domain knowledge (HPT discs, IPT disc seal arms, 2D excitation, frettage, flight cycles)"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of specified Rolls‑Royce Dart turbine engines to fix or inspect high‑pressure turbine (HPT) discs to prevent catastrophic 2D‑excitation/frettage failures. Operators must either carry out the permanent repair/replacement in Rolls‑Royce SB Da72‑533 Rev 2 or pass a one‑time inspection per SB Da72‑536 to gain a 750‑flight‑cycle extension (no later than 30 June 2004). Applies except where modification 1946 is already embodied; it revokes the earlier AD and adds an LBA inspection option."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dart-29-amdt-2-high-pressure-turbine-discs","history":"/api/acts/ad-dart-29-amdt-2-high-pressure-turbine-discs/history","analysis":"/api/acts/ad-dart-29-amdt-2-high-pressure-turbine-discs/analysis","conflicts":"/api/acts/ad-dart-29-amdt-2-high-pressure-turbine-discs/conflicts","importantCases":"/api/acts/ad-dart-29-amdt-2-high-pressure-turbine-discs/important-cases","documents":"/api/acts/ad-dart-29-amdt-2-high-pressure-turbine-discs/documents"}}