The region's air ambulance is back in business but mechanics are still puzzling over what caused one of its engines to malfunction during an emergency callout.

The failure grounded the Bell 412 for six hours, but Paul Bouchard, superintendent of aviation for the ambulance service, said the ambulance service would have called back-up aircraft into play if the need arose.

He told The Daily News on Friday that malfunctions like this are not uncommon in the aviation industry, but are rare among air ambulances.

"Within B.C. Ambulance and the aircraft we've had contracted, this is a unique situation," said Bouchard "It's being investigated and we'll find out what the cause was."

The helicopter was dispatched from Kamloops Airport to a dirt bike accident on Greenstone Mountain at about 1:30 p.m. A ground ambulance was also sent.

Bouchard said the helicopter was looking for a place to land when one of its two engines malfunctioned. The pilots shut down the engine and flew back to the airport, leaving the patient for the ground crew.

Bouchard was unable to provide an update on the injured person's condition.

The Bell 412 was grounded for about six hours while mechanics with CC Helicopters in Kamloops - which the ambulance service contracts out to - swapped out the engine.

Had an air ambulance been required, the service would have dispatched aircraft from other aviation contractors in the region. Bouchard said this wasn't necessary.

CC Helicopter president Ralph Emsland said the engine will eventually be shipped back to manufacturer Pratt & Whitney.

He said the Bell 412 is a reliable aircraft, which is why it's used as an air ambulance.

The helicopter is inspected and maintained daily. Emsland said a problem wasn't detected prior to Saturday's flight.

"It's proven itself in spades," he said.

Kamloops Airport manager Fred Legace said mechanical issues are possible in any aircraft, including commercial airlines.

He said aircraft are designed with redundant systems, which means if one part fails, another can take over and keep the machine in flight.

As is often the case, the engine will be inspected by Transport Canada certified aircraft engineers, who determine if the machinery can be put back into service.

"They go back to the shop and get fixed," he said.