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.
Turbomeca Turbine Engines - Arriel Series
AD/ARRIEL/19 Acceleration Controller Axle Of the Fuel Metering Unit
13/2004
Applicability: Turbomeca Arriel 2B turboshaft engines, incorporating TU 62A modification. Requirement: 1. Perform a ground check in mixed mode operation (refer to the AS350 B3 Flight
Manual section 8 task 3C, dealing with the control system mixed mode). Do not
fly the helicopter if the engine behaviour deviates from the results mentioned in the Flight Manual.
Requirement 1 may be performed and certified by the pilot in the Maintenance Release at the First-Flight-of-the-day inspection.
2. Check the fuel metering system and perform maintenance procedures prescribed by the Mandatory Service Bulletin (MSB) A292 73 2814 or the later revision approved by DGAC / EASA.
3. Repeat the maintenance procedures of requirement 2.
Note 1: DGAC Airworthiness Directive F-2004-139 as approved by EASA reference number 2004-8594 dated 10 August 2004 refers.
Compliance: 1. Before the first flight of the day, till Turbomeca MSB A292 73 2814 is complied with.
2. Within 20 operating hours of receiving parts provided by Turbomeca, and at the latest on 1 March 2005.
3. Every 200 hours (+/- 10 hours).
This Airworthiness Directive becomes effective on 23 December 2004.
Background: Sticking of the acceleration controller axle (a part of the Fuel Metering Unit) in its bearing can result in difficulty or impossibility to control the fuel flow rate in manual or mixed mode.
Turbomeca Turbine Engines - Arriel Series
AD/ARRIEL/19 (continued)
An unpredictable engine running in manual or mixed mode can cause gas generator or power turbine over-speed, leading to uncommanded or commanded in-flight engine shutdown. This situation on a single-engined helicopter may lead to an emergency autorotation landing.
James Coyne
Delegate of the Civil Aviation Safety Authority 8 November 2004
The above AD is notified in the Commonwealth of Australia Gazette on 1 December 2004.