An RAF Puma helicopter that crashed, killing two servicemen and injuring ten others, suddenly flipped on to its side and fell to the ground, witnesses said yesterday.

Flight Lieutenant David Sale, the Puma captain, and Sergeant Phillip Burfoot, a crew member, were killed instantly in the crash at 9pm on Wednesday. Remarkably, three of the passengers scrambled from the wreckage, suffering only bruises and cuts.

The soldiers on board as passengers were all from 1 Brigade, Infantry Training Battalion, based at Catterick, North Yorkshire.An RAF board of inquiry team yesterday began investigating the incident, which took place during a training exercise to the west of Catterick.

David Learmount, operations and safety editor at Flight International, said that if accounts that the helicopter rolled on to its side in mid-air were accurate, it was likely that its balancing mechanism might have failed.

He said: “It suggests to me that something broke that keeps the aircraft balanced. It could be one of hundreds of mechanical failures connected to either the main rotor or the tail rotor, which provides a counter balance.”

The crashed Puma had three RAF aircrew and nine soldiers on board. Flying low during a routine joint RAF and Army exercise, it lost power, tipped to one side and plummeted 80ft (24m) into a field.

Of the ten injured, one was in a critical condition and a second was seriously injured but was expected to pull through. They were airlifted to James Cook University Hospital in Middlesbrough.

Five others were described as stable but, to the astonishment of military observers, three men were able to walk almost unaided from the wreckage. An army source said: “Looking at the wreckage it is remarkable that anyone was able to crawl out alive.”

The Puma, which was from 33 Squadron, based at RAF Benson in Oxfordshire, broke up into three parts as it crashed into scrub on Hudswell Moor, near to disused farm buildings.

Andrew Pavey, 39, a coach driver from Colburn, near Catterick, watched as the Puma pitched at a 90-degree angle then “went down to the ground”. He said: “The helicopter was making an unusual engine noise, as if misfiring, just before it crashed. It had suddenly shot up out of the woods, straight up in the air, then it went on its side and disappeared behind the trees. There was no explosion or flames.”

It was the twelfth Puma to be lost through an accident since 1990, raising concerns over the transport helicopter’s serviceability.

But the Ministry of Defence said there were no plans to ground the RAF’s other 32 Pumas, some of which are deployed in Iraq. Four months ago two Pumas were involved in a mid-air collision in Iraq, in which two soldiers were killed.

The Puma first entered service in 1971, but the MoD plans to keep it for another 15 years and give it a complete upgrade.

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