AIRWORTHINESS DIRECTIVE
For 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.
Rolls Royce Turbine Engines - Dart Series
AD/DART/29
Amdt 2
High Pressure Turbine Discs 10/2003
Applicability: 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).
Requirement: 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
2. 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.
Note: German LBA AD 2001-116/6 refers.
Compliance: For Requirement 1: As detailed in the Requirement document.
For Requirement 2: As contained in the Requirement. This Amendment becomes effective on 2 October 2003.
Background: 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.
Rolls Royce Turbine Engines - Dart Series
AD/DART/29 Amdt 2 (continued)
Amendment 1 of this Airworthiness Directive became effective on 4 October 2001. The original issue of this Airworthiness Directive became effective on 12 July 2001.
Jim Coyne
Delegate of the Civil Aviation Safety Authority 19 August 2003
The above AD is notified in the Commonwealth of Australia Gazette on 10 September 2003.
Overview
The Civil Aviation Safety Authority (CASA) introduced the Airworthiness Directive (AD) for Rolls Royce Turbine Engines - Dart Series under the Civil Aviation Safety Regulations 1998 (CASR 1998) to address a critical safety issue related to high pressure turbine (HPT) disc failures in certain models of Rolls Royce Dart series engines. This AD, specifically AD/DART/29 Amdt 2, aims to correct an unsafe condition identified in the HPT discs of these engines, which had resulted in several incidents of HPT disc release due to 2D excitation and frettage between the HPT disc and Intermediate Pressure Turbine (IPT) disc seal arms. The AD mandates either the replacement or reworking of affected HPT discs in accordance with Rolls Royce Service Bulletin (SB) Da72-533 Revision 2, or alternatively, a one-time inspection in line with Rolls Royce SB Da72-536, which may extend interim compliance times. This directive was issued to ensure the continued airworthiness of the affected aircraft and to mitigate the risk of further incidents.
Scope and Application
This Airworthiness Directive (AD) applies specifically to Rolls Royce Dart series engines that are detailed by model in Rolls Royce Service Bulletin (SB) Da72-533, Revision 2 and do not incorporate modification 1946. The AD is issued under the authority of the Civil Aviation Safety Authority (CASA) delegate and pertains to Commonwealth jurisdiction, impacting all operators and owners of the specified engines within Australia. The directive mandates either the replacement or rework of affected high pressure turbine (HPT) discs according to the procedure outlined in Rolls Royce SB Da72-533 Revision 2, or alternatively, a once-only inspection in line with Rolls Royce SB Da72-536. This inspection, if satisfactory, can extend the interim compliance times of Rolls Royce SB Da72-533 by 750 flight cycles from the date of inspection, but not beyond 30 June 2004. The AD was introduced to address safety concerns arising from in-service failures of HPT disc diaphragms, specifically due to 2D excitation of the HPT assembly as a result of frettage between the HPT disc and Intermediate Pressure Turbine (IPT) disc seal arms.
Key Provisions
The Airworthiness Directive (AD) AD/DART/29 Amdt 2, issued by the Civil Aviation Safety Authority (CASA), pertains to the Rolls Royce Dart series engines. This directive, as per section 10/2003, applies to specific models of Rolls Royce Dart series engines as detailed in Rolls Royce Service Bulletin (SB) Da72-533, Revision 2, and excludes those incorporating modification 1946 (SB Da72-533). The directive mandates two primary actions to address the identified safety issue: first, the replacement or rework of affected high pressure turbine (HPT) discs in accordance with the procedure outlined in Rolls Royce SB Da72-533 Revision 2 (section 1(a)); or second, a one-time inspection in compliance with Rolls Royce SB Da72-536 (section 1(b)). If the inspection is satisfactory, it allows for an extension of the interim compliance times of Rolls Royce SB Da72-533 by 750 flight cycles from the date of inspection, but not beyond 30 June 2004 (section 1(b)). This extension is contingent upon the satisfactory inspection result and the recognition of German LBA AD 2001-116/6 as the authoritative document for the AD. The compliance timelines are detailed in the respective requirement documents, with the amendment becoming effective on 2 October 2003 (section 3).
The obligations imposed by this AD on the parties or entities it governs are clear and specific. Operators of the affected Rolls Royce Dart series engines must ensure that either the replacement or rework of the HPT discs is carried out as per Rolls Royce SB Da72-533 Revision 2 or that a one-time inspection is conducted in compliance with Rolls Royce SB Da72-536. The AD emphasises the importance of adhering to the detailed procedures set out in the referenced service bulletins and the satisfaction of inspection criteria to allow for the compliance time extension. The directive also mandates that these actions are taken in accordance with the compliance timeline specified in the requirement documents.
Failure to comply with the AD AD/DART/29 Amdt 2 could result in serious safety implications, as the directive was issued to address in-service failures of HPT disc diaphragms that led to HPT disc release events. The AD was prompted by incidents attributed to 2D excitation of the HPT assembly due to frettage between the HPT disc and Intermediate Pressure Turbine (IPT) disc seal arms. While the AD itself does not specify offences or penalties, non-compliance with CASA directives can lead to significant civil and criminal consequences under the Civil Aviation Act 1988. These can include fines and imprisonment, particularly if the non-compliance results in an unsafe condition that endangers the safety of aircraft operations. The severity of the penalties reflects the critical nature of airworthiness directives in maintaining the safety standards required by Australian aviation law.