AD/Arriel/19 Amdt 1 Fuel Metering Unit Acceleration Controller Axle (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/ARRIEL/19 and issues the following AD under subregulation 39.001(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 Amdt 1 Fuel Metering Unit Acceleration
Controller Axle 7/2007

Applicability:

Turbomeca ARRIEL 2B turboshaft engines, incorporating TU 62A modification that have not been modified to incorporate modification TU 132.

Note 1:  These engines are installed in, but not limited to, Eurocopter AS 350 B3 helicopters.

Requirement:

1.    Check the fuel metering system and perform the maintenance procedures as detailed in Turbomeca Mandatory Service Bulletin (MSB) A292 73 2814
Update No. 2 or the later NAA approved revision.

2.    Repeat the maintenance procedures of requirement 1.

Note 2:  EASA AD 2007-0026 dated 1 February 2007 refers.  This AD supersedes DGAC AD F-2004-139.

Compliance:

1.    Remains unchanged as detailed in the original issue of this AD as Prior to
1 March 2005.

2.    At intervals not to exceed 210 flight hours, until such time a HMU modified in accordance with Turbomeca modification TU 132 is fitted.

This Amendment becomes effective on 5 July 2007.

Background:

Sticking of the acceleration controller axle (a part of the Fuel Metering Unit) in its bearing can result in inability to accurately control the fuel flow rate in manual or mixed mode.

This amendment removes from the applicability section of this AD those HMU’s that have incorporated a modification that prevents the sticking of the acceleration controller axle.  In addition, the requirement to carry out a daily mixed mode operation has been deleted as these actions have been superseded by the check and maintenance actions detailed in this AD.

The original issue of this AD became effective on 23 December 2004.

David Villiers
Delegate of the Civil Aviation Safety Authority

24 May 2007