AD/EC 135/7 Amdt 1 - Automatic Engine Control (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Eurocopter EC 135 Series Helicopters

AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/EC 135/7 and issues the following AD under subregulation 39.1 (1) of CAR 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.

Background: The German Luftfahrt-Bundesamt has advised that several instances have been reported of a FADEC FAIL caution indication being displayed for one engine. The caution display was caused by a parameter discrepancy, which was generated within the Fuel Main Metering Unit and transmitted to the FADEC. This discrepancy may lead to "freezing" of the Fuel Main Metering Valve at its momentary position, resulting in loss of the automatic engine control in the affected system.

The original issue of this Directive introduced a synchronisation procedure that prevented the occurrence of the discrepancy between the parameters and thus sustained the automatic engine control.

This amendment limits the applicability to EC 135 T1 helicopters fitted with Arrius 2B1 engines and requires the installation of a new software version designed to prevent failure of the automatic engine control in those helicopters. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES