F-35 Lightning II fan blade rubbing against part may explain fire

"The aircraft is still awaiting US Department of Defence clearance but we are hopeful that it will fly at the air show by the end of the week," Farnborough's organisers said, a sentiment echoed by Mr Norman.

Britain is a leading player in the Lockheed Martin jet programme and has said it will buy at least 48 F-35B jump jets to fly from RAF Marham and the new Queen Elizabeth class aircraft carriers. Three British test aircraft are already being put through their paces in America.

Despite the major setbacks, Mr Norman insists the F-35 planes will improve Britain's capabilites.

The accident has already meant the jets had to cancel their first appearances outside the US at the naming ceremony of HMS Queen Elizabeth and last week’s Royal International Airt Tattoo at Fairford. Both events had to instead make do with a full-sized model of the plane.

Three US Marine F-35Bs in Maryland and one British jet in Florida are on standby to make the seven hour Atlantic crossing accompanied by fuel tankers.

Shaun Ormrod, chief executive of the organisers, said: “Crews and aircraft are literally ready to go at an hour’s notice. It’s just getting that clearance to say the aircraft are ready to fly.”

Even if the planes were able to make the Atlantic crossing to RAF Fairford on Monday, after further tests and preparation they would be unlikey to get to Farnborough before Wednesday.

American commanders extended a safety order grounding the jets at the weekend saying they had been unable to find the “root cause” of the blaze.

Marine Lt General Jon Davis, deputy commandant for aviation, said: “I think we're being very, very conservative in our approach to this, which is the right thing to do.

“This is a fantastic program and we don't want to do anything to screw it up ... No one wants to do anything that isn't prudent."

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