{"id":"F2005L01766","name":"AD/DART/31 - Intermediate Pressure Turbine Disc","slug":"ad-dart-31-intermediate-pressure-turbine-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":35875,"registerId":"commonwealth-F2005L01766-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Rolls Royce Turbine Engines - Dart Serie","sectionType":"division","heading":"Rolls Royce Turbine Engines - Dart Series","content":"### Rolls Royce Turbine Engines - Dart Series\n\n| AD/DART/31 | Intermediate Pressure Turbine Disc | 8/2005 |\n| ---------- | ---------------------------------- | ------ |\n\n| Applicability: | Rolls-Royce Dart Turboprop Engine models:528-7E, 528D-7E,529-7E, 529-7H, 529-8E, 529-8H, 529-8X, 529-8Y, 529-8Z, 529D-7E, 529D-7H, 529D-8E, 529D-8H, 529D-8X, 529D-8Y, 529D-8Z,532-7, 532-7L, 532-7N, 532-7P, 532-7R,533-2,534-2,535-2, 535-7, 535-7R,536-2, 536-2T, 536-7, 536-7P, 536-7R,542-10, 542-10J, 542-10K, 542-4, 542-4K,543-10, 543-10K,550-2,552-2, 552-7, and 552-7R;that have the Initial Issue or Revision 1, but not Revision 2 or later Revisions of Rolls Royce Service Bulletin (SB) Da72-533 incorporated and which have not been subject to a dimensional inspection of the Intermediate Pressure Turbine (IPT) disc in accordance with the Engine Overhaul Manual, Chapter 72-61-1. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Carry out dimensional inspection of the IPT disc in accordance with SB Da72- 538 dated 10 June 2005 or later approved revisions;OR2. Carry out ultrasonic inspection of High Pressure Turbine (HPT) / IPT disc seal arm in accordance with Rolls Royce SB Da72-536. If the ultrasonic inspections shows wear outside allowable limits, carry out dimensional inspection of the IPT disc per Requirement 1 of this AD.                                                                                                                                                                                                                                                                                  |\n|                | 3. Rework or replace the IPT disc, if wear outside allowable limits has been established as a result of inspection per Requirement 1 of this Directive.Note: German LBA Airworthiness Directive (AD) D-2005-197, as approved by EASA under approval number 2005-5848 dated 10 June 2005 refers.                                                                                                                                                                                                                                                                                                                                                                                                           |\n| Compliance:    | 1. After effective date of the AD, but not later than 31 January 2006.2. After effective date of the AD, but not later than 31 January 2006.3. Before installation of the IPT disc in the engine, after effective date of the AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |\n|                | This Airworthiness Directive becomes effective on 4 August 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| Background:    | Since 1972 there have been a number of High Pressure Turbine (HPT) disc diaphragm failures on in service engines, three resulted in the HPT disc being released. The failures have been attributed to excitations of the HPT assembly as a result of frettage between the HPT disc and Intermediate Pressure Turbine (IPT) disc seal arms. In extreme cases this can result in high cycle fatigue failure initiating in the seal arm radius.The actions specified by this Airworthiness Directive are intended to prevent HPT disc failure, which can result in an uncontained engine failure and damage to the aircraft.                                                                                 |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n24 June 2005","sortOrder":0},{"sectionNumber":"AD/DART/31","sectionType":"part","heading":"AD/DART/31","content":"## AD/DART/31","sortOrder":1},{"sectionNumber":"Intermediate Pressure Turbine Disc","sectionType":"part","heading":"Intermediate Pressure Turbine Disc","content":"## Intermediate Pressure Turbine Disc","sortOrder":2},{"sectionNumber":"8/2005","sectionType":"part","heading":"8/2005","content":"## 8/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive remains aligned with its stated safety objective to prevent HPT disc failure by addressing frettage and wear between HPT and IPT components. It refines applicability to engines that have not incorporated SB Da72‑533 Revision 2 rather than expanding obligations to all engines, and mandates inspections and corrective action with set deadlines and an installation prohibition for non‑compliant parts (see Applicability; Requirements 1–3; Compliance)."},"complexity_factors":["Long, specific list of affected engine models increases tracking and applicability complexity (Applicability).","Applicability depends on incorporation status of a specific service bulletin revision (SB Da72‑533 Revision 2), requiring record checks.","Two alternative inspection paths with conditional follow‑up: dimensional inspection (Requirement 1) or ultrasonic inspection with conditional dimensional follow‑up (Requirement 2).","Mandatory corrective action (rework or replace) and prohibition on installing non‑compliant IPT discs (Requirement 3; Compliance).","Firm compliance deadlines and an effective date create short implementation windows (Compliance: effective 4 Aug 2005; deadlines to 31 Jan 2006).","Relies on external technical material (Rolls‑Royce SBs and Engine Overhaul Manual) for inspection methods and allowable wear limits, adding cross‑referencing work for maintainers.","Cross‑reference to foreign authority documents (German LBA AD and EASA approval) increases regulatory provenance considerations."],"plain_english_summary":"This directive requires operators of specified Rolls‑Royce Dart turboprop engines (those not fitted with SB Da72‑533 Revision 2) to inspect the Intermediate Pressure Turbine (IPT) disc by a dimensional check or an ultrasonic check of the seal arm; if wear exceeds limits the disc must be reworked or replaced before installation. It affects aircraft operators and maintenance organisations, who fund and carry out the inspections and any repairs, and aims to reduce risk of High Pressure Turbine disc failure and uncontained engine events."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific mechanical failure mode in a defined set of Rolls-Royce Dart engine models. The applicability criteria are precise but do not represent scope creep beyond the original safety purpose of preventing HPT disc failures."},"complexity_factors":["Dense applicability clause listing 34 specific engine models plus conditional criteria (Service Bulletin revision status AND overhaul inspection history)","Nested conditional logic: Requirement 2 triggers Requirement 1 if ultrasonic inspection finds defects","Cross-reference to German LBA AD and EASA approval number 2005-5848 for technical standards","Multiple compliance dates with different triggers (after effective date vs before installation)","Technical aviation terminology requiring specialised knowledge (frettage, high cycle fatigue, seal arm radius, uncontained engine failure)"],"plain_english_summary":"This AD mandates inspections and, if needed, rework or replacement of the Intermediate Pressure Turbine (IPT) disc on certain Rolls‑Royce Dart turboprops that lack a specific safety update, to prevent fretting-related failures that have led to uncontained disc releases. It allows dimensional or ultrasonic-plus-follow‑up inspections to catch wear before failure.\n\nIt affects operators and maintenance organisations of listed Dart engines (e.g., on Fokker F27/HS 748 types). Compliance by 31 January 2006."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dart-31-intermediate-pressure-turbine-disc","history":"/api/acts/ad-dart-31-intermediate-pressure-turbine-disc/history","analysis":"/api/acts/ad-dart-31-intermediate-pressure-turbine-disc/analysis","conflicts":"/api/acts/ad-dart-31-intermediate-pressure-turbine-disc/conflicts","importantCases":"/api/acts/ad-dart-31-intermediate-pressure-turbine-disc/important-cases","documents":"/api/acts/ad-dart-31-intermediate-pressure-turbine-disc/documents"}}