JUSTIN WASTNAGE & STEWART PENNEY / LONDON
Redesign of third axial compressor stage of Makila 2A powerplant sets back EC225
Further details have emerged of problems affecting the Eurocopter EC225/EC725 helicopter. The aircraft was due for certification at the end of this year, but this has been pushed back to late 2003 (Flight International, 15-21 October).
Problems with development of the Turbomeca Makila 2A turboshaft for the helicopter, a derivative of the Cougar/Super Puma, and a decision to modify the cockpit have led to the delay. The principal changes are a five-bladed main rotor and uprated dynamic system.
Eurocopter says it decided last year to develop a new glass cockpit and autopilot following a marketing survey in 2000 which revealed "a strong demand for improved ergonomics, performance and lower maintenance cost on the avionics system".
The decision to upgrade the cockpit meant extra work and a new development schedule with "a certification date moved from the end of 2002 to mid-2003". Eurocopter claims, however: "It was not a delay." Observers question the advisability of starting the Cougar redesign without planned avionics and autopilot improvements.
Eurocopter says engine development has taken longer than expected, which "resulted in a six-month delay for the programme. The certification is now set for the end of 2003, and first delivery in early 2004. This is a delay."
Turbomeca says it has had to redesign the third axial stage of the compressor "to improve the surge margin". The Makila 2A's compressor comprises three axial and a single centrifugal stage. The engine company adds: "This caused a six-month delay."
The Makila 2A is uprated to 1,565kW (2,100shp), from the 1,375kW Makila 1A2 used in earlier Cougars. The 2A has a bigger compressor able to handle increased air mass-flow rates and new single-crystal blades in turbine first stage. It also has a dual-channel digital engine control.
Turbomeca says the decision to redesign the third stage was taken earlier this year following sea level bench testing. Philippe Perrot, Makila programme manager, says the aerodynamics of the third stage rotor and stator have been modified, and hardware testing will begin this month.
Engines built to the new standard will be shipped to Eurocopter in January, with civil certification by France's DGAC authority scheduled for December next year. Eurocopter says that launch customers - the French army for the EC725 and CHC for the civil variant - have been "kept informed".
Source: Flight International
