Eurocopter is pressing ahead with tests of a hybrid powertrain it believes will increase safety on single-engined helicopters in the event of engine failure.

As well as the regular turboshaft engine, the system also uses a battery-powered electric motor which automatically cuts in if the main powerplant fails.

This initially provides power to ensure there is no drop in rotor speed and then provides sufficient thrust immediately prior to landing to safely flare the aircraft.

Jean-Michel Billig, executive vice-president engineering at Eurocopter, said the hybrid system removes a major source of stress for pilots during an auto-rotation landing.

"The reaction of our test pilots was one of absolute amazement. They could not tell the difference when it switched to battery power," he said.

"It removes a lot of stress and panic - you know you'll make it."

The airframer will carry out further tests on an AS350 Ecureuil to ensure performance criteria are met, before making a decision early next year whether to formally offer the drivetrain to its customers.

One key factor is the size and weight of the system, as the electric motor and lithium ion polymer battery are installed in the centre area of the helicopter.

Billig said: "If we have to reduce the payload by one or two passengers [to fit it] then we will not bring it to market."

Billig said the system is "platform agnostic" and would be suitable for any of its single-engined helicopters.

Although the primary driver for the project was to increase safety, Billig said the tests have yielded data suggesting the hybrid powertrain may have future environmental benefits.

"We are currently capturing these ideas and will make it another project for next year or the year after," he said.

Eurocopter is also working with external partners to produce a diesel-powered helicopter, with first flight pegged for late 2013. It believes diesel has huge potential to lower an aircraft's fuel consumption.

Source: Flight International