AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (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 (Allison) Turbine Engines - AE 2100 Series
AD/AE 2100/1 High Pressure Turbine Wheel 7/2004
Applicability: Rolls-Royce Corporation (formerly Allison Engine Company) models AE 2100A and AE 2100C turboprop engines with high pressure turbine (HPT) wheel part number (P/N) 23050912 installed; AE 2100A turboprop engine with turbine wheel P/N 23063462 serial number (SN) MM14062 installed; AE 2100A, AE 2100C, AE 2100D3 turboprop engines with 2nd stage HPT wheels with SN's prior to MM183060.
Requirement: 1. Perform a one-time acid etch inspection to the 2nd stage high pressure turbine wheel in accordance with the Accomplishment Instructions contained in the following Rolls-Royce Alert Service Bulletins, Table 1.
Table 1.
AE models | Rolls-Royce service bulletin |
AE 2100A | AE 2100A-A-72-234, Revision 2, dated October 13, 2000 or Revision 3, dated June 19, 2001. |
AE 2100C | AE 2100C-A-72-183, Revision 2, dated October 13, 2000 or Revision 3, dated June 19, 2001. |
AE 2100D3 | AE 2100D3-A-72-179, Revision 2, dated October 13, 2000 or Revision 3, dated June 19, 2001. |
2. If damage is discovered, replace the turbine wheel with a serviceable part.
3. Do not install any 2nd-stage gas-generator turbine wheel listed in Table 2 of this Directive, unless it has been inspected as specified in Requirement 1 of this Directive.
Note: FAA AD 2001-17-31 Amdt 39-12423 refers.
Compliance: For Requirement 1: As detailed in Table 2 of this Directive.
Table 2.
Models | With turbine wheel | Mandatory |
AE 2100A, AE2100C | 23050912 | Before 4,800 cycles since new (CSN). |
AE 2100A | 23063462-S/N MM14062. | Before 4,800 CSN. |
AE2100D3 | 23050912 | Before 3,200 CSN. |
All other AE 2100A, AE 2100C and AE2100D3 | 23063462, 23064822, 23070673, 23065892, 23069116, 23064473, 23064474, 23068072, 23070672 and 23070675 with S/N's MM183060 and before. | At next shop visit. |
All AE 2100A and AE 2100C | 23069592 with S/N MM183060 and before. | Next exposure but not to exceed 16,800 CSN. |
All 2100D3 | 23069592 with S/N MM183060 and before. | Next exposure but not to exceed 14,100 CSN. |
For Requirement 2: Before further flight.
For Requirement 3: From the effective date of this Directive. This Airworthiness Directive becomes effective on 8 July 2004.
Background: This Directive is prompted by a report of a 2nd stage HPT wheel that was returned from the field with cracks in the aft bore face. The actions specified by this Directive are intended to detect and prevent early development of cracks due to low cycle fatigue of the 2nd stage HPT wheel in the aft bore face that can lead to wheel failure, power loss, and possible damage to the aeroplane.
James Coyne
Delegate of the Civil Aviation Safety Authority 27 May 2004
The above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.
Overview
The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive (AD) AE 2100/1 on 7 July 2004 to address an unsafe condition identified in Rolls-Royce Corporation (formerly Allison Engine Company) models AE 2100A and AE 2100C turboprop engines, specifically relating to the high pressure turbine (HPT) wheel. This AD was issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 (CASR 1998) and is intended to correct an issue of low cycle fatigue leading to cracks in the aft bore face of the 2nd stage HPT wheel, which can result in wheel failure, power loss, and potential damage to the aircraft. The AD requires a one-time acid etch inspection of the 2nd stage HPT wheel, with subsequent replacement if damage is found, and prohibits the installation of certain turbine wheels unless they have been inspected as specified. Compliance timelines are set for various models and serial numbers, with the AD becoming effective from 8 July 2004.
Scope and Application
The Airworthiness Directive (AD) issued under the Civil Aviation Safety Regulations 1998 (CASR) applies specifically to Rolls-Royce Corporation (formerly Allison Engine Company) models AE 2100A and AE 2100C turboprop engines equipped with certain high pressure turbine (HPT) wheels. The directive mandates that a one-time acid etch inspection be conducted on the 2nd stage high pressure turbine wheels to detect potential cracks in the aft bore face, a condition that can lead to wheel failure, power loss, and potential damage to the aircraft. This inspection must be carried out in accordance with the instructions provided in specified Rolls-Royce service bulletins and before certain cumulative service cycles, depending on the engine model and serial number of the turbine wheel. The directive also prohibits the installation of certain turbine wheels unless they have been inspected as specified. The AD applies to engines in the Commonwealth of Australia and is enforced by the Civil Aviation Safety Authority (CASA). There are no stated exclusions or exemptions within the text of this directive, and it becomes effective on 8 July 2004.
Key Provisions
The key provisions of this Airworthiness Directive (AD) are outlined under the applicability, requirement, and compliance sections. Specifically, the AD applies to Rolls-Royce Corporation (formerly Allison Engine Company) models AE 2100A and AE 2100C turboprop engines with certain high pressure turbine (HPT) wheel part numbers installed, as well as AE 2100A turboprop engines with turbine wheel part number 23063462 serial number MM14062 installed and AE 2100A, AE 2100C, AE 2100D3 turboprop engines with 2nd stage HPT wheels with certain serial numbers prior to MM183060. The requirements section mandates a one-time acid etch inspection to the 2nd stage high pressure turbine wheel, as detailed in the Rolls-Royce Alert Service Bulletins, and replacement of the turbine wheel if damage is found. The AD also prohibits the installation of any 2nd-stage gas-generator turbine wheel listed in Table 2 unless it has been inspected as specified in Requirement 1. The compliance section sets out the timeframes for these requirements, with the inspection needing to be performed before a specified number of cycles since new, and replacement of the turbine wheel needing to be done before further flight.
The AD imposes obligations on engine owners, operators, and maintenance personnel to ensure the specified inspection and replacement of turbine wheels is carried out in accordance with the Rolls-Royce Alert Service Bulletins. Owners and operators of affected aircraft must ensure that the required inspections and any necessary replacement of turbine wheels are performed before the specified flight hours or cycles, as outlined in the AD. Maintenance personnel must carry out the inspections and replacements in accordance with the instructions in the Rolls-Royce Alert Service Bulletins. Failure to comply with the AD may result in the engine or aircraft being deemed unairworthy.
Failure to comply with the requirements of this AD may result in the engine or aircraft being considered unairworthy. There are no specific penalties outlined in the AD itself, but non-compliance could lead to enforcement actions by the Civil Aviation Safety Authority (CASA), including the potential for fines and other enforcement measures. Additionally, failure to comply with the AD could result in safety issues, including the risk of turbine wheel failure, power loss, and potential damage to the aircraft.