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.

Allison Turbine Engines - 250 Series

AD/AL 250/83 Third-Stage Turbine Wheels 10/2004

Applicability:  Rolls-Royce Corporation (formerly Allison Engine Company), models 250-C28, - C28B, and -C28C turboshaft engines with third-stage turbine wheels, part number (P/N) 6899383, listed by serial number (SN) in Table 1 of this Directive:

Table 1. - SNs of Affected Third Stage Turbine Wheels

Note 1: These engines are installed on, but not limited to, Bell Helicopter Textron 206L-1; Eurocopter Deutschland BO 105 LS A-1; and Eurocopter Canada BO 105 LS A-3 helicopters.

Requirement: 1. Replace the third-stage turbine wheel with a turbine wheel not listed in Table 1 of this Directive.

2. Do not install third- stage turbine wheels that are listed in Table 1 of this AD, into any engine.

Note 2: FAA AD 2004-14-02 Amdt 39-13711 refers.

Compliance:  For Requirement 1: For third-stage turbine wheels with less than 250 operating hours’ time since new (TSN) on the effective date of this Directive, before accumulating 300 operating hours TSN.

For any third-stage turbine wheel with 250 or more operating hours TSN on the effective date of this Directive, before accumulating an additional 50 operating hours.

For Requirement 2: From the effective date of this Directive.

This Airworthiness Directive becomes effective on 30 September 2004.

Background: This Directive results from three reports of third-stage turbine wheel blade and shroud failures. The issue of this Directive is to prevent loss of power and uncommanded engine shutdown due to failure of the third-stage turbine wheel blade and shroud.

Gary J Carr

Delegate of the Civil Aviation Safety Authority 5 August 2004

The above AD is notified in the Commonwealth of Australia Gazette on 8 September 2004.