AD/MAKILA/7 Amdt 1 - Digital Engine Control Unit Software (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/MAKILA/7 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 - Makila Series AD/MAKILA/7 Amdt 1 Digital Engine Control Unit Software 7/2007

Applicability: Makila 1A2 turboshaft engines. Note 1: These engines are known to be installed on, but not limited to, Super Puma Mark II helicopters. Requirement: 1. If not previously accomplished in accordance with the original issue of this Directive, replace the digital engine control unit (DECU) with a DECU incorporating Modification TU 244C (upgrade of software version 9 to version 11) in accordance with Turbomeca Mandatory Service Bulletin No A298 73 0244 Update 1 dated 30 March 2007 update. 2. Engines, post Modification TU 244C, may only be installed on a helicopter if the other engine is either post Modification TU 244C or TU 230C (previous version of the control system software). Note 2: EASA AD 2007-0143 refers. Compliance: For Requirement 1 - No later than 30 November 2008. For Requirement 2 - As of the effective date of this Amendment. This Amendment becomes effective on 5 July 2007. Background: The French Direction Générale de l'Aviation Civile (DGAC) advised that a backup law at 65% of NG (gas generator speed) has been added to the control system of Makila 1A2 engines in order to limit the acceleration of the free turbine overspeed in the event of a failure of the drive train between the engine and the main gearbox.