RAF Nimrod spy planes flying over Iraq and Afghanistan have been losing hundreds of gallons of fuel during mid-air refuelling, according to leaked official reports (read them here: report 1 and report 2).

The documents record large amounts of fuel running along the inside of the fuselage and pouring out of the rear of the aircraft leaving it at risk of fire or explosion.

Air-to-air refuelling has continued despite it being the suspected cause of a mid-air explosion over Afghanistan in September that killed 14 Nimrod crew members.

One former RAF engineer said he believed the decision to continue with air-to-air refuelling in the face of the leaks was “criminal”.

A former RAF pilot said the scale of the leaks was shocking. “You never lose fuel like that. It is incredibly dangerous, especially if the fuel is atomised.”

A leak in the air-to-air refuelling system caused by excessive pressure is believed to have led to the fire on board Nimrod XV230 which caused it to explode.

Official air incident reports show leaks were much larger than previously thought with pressure building up inside the Nimrod’s refuelling system to more than twice the level it should have been.

The Ministry of Defence (MoD) has admitted repeated small fuel leaks. But in one incident in November last year hundreds of gallons of fuel poured out of the back of the aircraft.

The crew of the RAF tanker aircraft refuelling the Nimrod reported that the fuel coming out of the back of the aircraft was “similar to that of a fuel dump”, when aircraft dump large amounts of fuel before landing.

Fuel had built up in the bomb bay, which was opened on two occasions to get rid of it. Air-to-air refuelling was suspended for a short period in the wake of the November incident and new operating procedures were introduced.

But even after these were put in place, the leaks continued. A second report covering an incident a month later shows the aircraft leaking 958 gallons of fuel.

“On landing, the rear fuselage was found to be covered in fuel,” the air incident report said. “Fuel had gathered in the doors.”

There was a pool of fuel inside an aerial housing and flares were found to be covered in fuel.

“There was fuel found covering the plastic base of the flares,” the report said. “Each flare was removed from its housing and evidence of fuel was found approximately a third of the way up the flare housings.”

Jimmy Jones, a former RAF engineering officer who worked on the Nimrod aircraft, said the air-to-air refuelling system had been fitted quickly for the Falklands war in 1982 and was not designed for extensive use.

“It was fitted so that the aircraft, in time of crisis, could transit from one theatre of operation to another. It was not fitted with ‘everyday’ use in mind.

“Personally, I believe it was criminal to continue flying after the explosion on board XV230 without a full understanding of what caused it.”

The aircraft that exploded is believed to have sprung a leak during midair refuelling while it was monitoring a Nato offensive against Taliban insurgents west of Kandahar in southern Afghanistan on September 2 last year.

The fuel appears to have leaked into the bomb bay where it caught fire, either as the result of an electrical fault or hot air leaking from a heating pipe.

The pilot reported a fire in his bomb-bay. He tried to reach Kandahar air base, taking the aircraft down from 23,000ft to 3,000ft in 90 seconds.

An RAF Harrier aircraft followed the Nimrod down and saw a wing explode, followed a few seconds later by the rest of the aircraft.

A board of inquiry was due to report this month. A draft report was known to be circulating in the MoD in April. But the report is not now expected to be released until September at the earliest.

Air Chief Marshal Sir Glenn Torpy, chief of the air staff, said last month that he was “very concerned” about the number of leaks but the aircraft was “as safe as it needs to be”.

The Ministry of Defence said: “The Nimrod has an excellent safety record and is airworthy and fit to fly. If the RAF didn’t have confidence in the aircraft, it would not continue to fly it.”

Read Mick Smith's defence blog at www.timesonline.co.uk/micksmith

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