Ad/Arrius/15 - Engine Fuel and Control - Balancing Piston Life Limit (Cth)

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 39.001(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 - Arrius Series

AD/ARRIUS/15 Engine Fuel and Control - Balancing
Piston Life limit 10/2008

Applicability:

Turboméca ARRIUS 1A turbo-shaft engines.

Note 1:  These engines are known to be installed in, but not limited to Eurocopter AS355N helicopters.

Requirement:

Modify the cycle life limit value of the balancing piston in the engine log book in accordance with Turboméca Mandatory Service Bulletin N° 319 72 0811 and update accordingly the approved operator’s maintenance programme.

The use of later approved revisions of this document is acceptable for compliance with the requirements of this AD.

Note 2:  EASA AD 2008-0133 dated 17 July 2008 refers.

Compliance:

Before 31 December 2008, unless previously accomplished.

This Airworthiness Directive becomes effective on 25 September 2008.

Background:

The cycle life limit value for ARRIUS 1A balancing piston Part Number (P/N)
0 319 20 152 0, was initially set at 40,000 cycles, but has been reduced to 16,000 cycles, following the discovery of a calculation error during a recent review of the ARRIUS 1 engine family files.

The new cycle life limit value for the balancing piston has been incorporated end of 2007 in ARRIUS 1A Maintenance documentation.

Failure to comply with the new life limits provided in the Airworthiness Limitations Section of ARRIUS 1A Maintenance documentation could potentially result in an engine in-flight-shutdown and the release of high energy debris.

James Coyne
Delegate of the Civil Aviation Safety Authority

25 July 2008