Germany is to acquire a fleet of five light-twin rotorcraft to make up for a problem discovered with its 14 Airbus Helicopters EC135 basic trainers that leaves them unsuitable to perform certain crucial training manoeuvres.

Speaking at an event at the German army's aviation training school in Bückeburg near Hannover, Lt Col Guido Krahl said the requirement had been created specifically to fulfil a need for auto-rotation training.

The EC135s, he says, are unable to be used for the task as the service requires auto-rotations to be carried out to the ground, in order to adequately prepare pilots for combat scenarios.

"When you do it a lot you get a vibration with the rotorblades, and it doesn't allow the user to do it so much or so often in a short sequence," Krahl says.

He says the issue could cause "small cracks" in the blades, which would then need to be replaced. The service has been aware of the issue since it began operating the helicopters in 2010.

"Today our defence ministry is in close connections with helicopter manufacturers to get new aircraft for auto-rotations," he adds.

For its part, Airbus Helicopters insists there is no problem performing the manoeuvre in the EC135 "even to the ground, as it is part of the certification". However, the potential for costly damage to be incurred may make the aircraft unsuitable for entry-level students, it adds.