Page last updated at 12:52 GMT, Tuesday, 2 May 2006 13:52 UK

Can safety foam save RAF lives?

Hercules C-130
Installing foam fuel tanks was one recommendation after the crash

RAF pilots requested that foam safety devices be fitted to the fuel tanks of Hercules planes two years before an attack in which 10 men died, a BBC investigation has discovered. Would the foam have saved their lives?

On 30 January 2005 a Hercules travelling from Baghdad to Balad was hit by ground-to-air fire which caused an explosion in the right-hand wing fuel tank.

The wreckage was found by US helicopters about 40 km (25 miles)

north-west of Baghdad. All 10 men on board were killed.

The findings of a board of inquiry published last December said the crash was not survivable but did admit that the lack of a fuel tank safety system could have contributed to the crash.

Would those 10 men still be alive? I don't know
Defence analyst Andrew Brookes

Last week the Ministry of Defence confirmed it would fit safety equipment to those Hercules C-130 aircraft deemed most at risk.

So how does the foam work and could it save lives?

The image of planes catching fire was ubiquitous in World War II and the technology to address this has been known for decades.

After the Vietnam War, the US forces introduced safety foam on their planes and it is now standard issue.

Fuel tank explosions occur in the space above the fuel, when a spark ignites the dangerous mix of vapour and air.

Wider problem

The greater the amount of air, and lower the volume of fuel, the greater the risk of explosion because the flame spreads across a greater area and the compression of the liquid is more intense.

But with a safety foam installed, the vapour ignition is confined to the area immediately around the ignition source and cannot "travel".

Whether such a modification to the Hercules could have saved those lives is not clear, says defence analyst Andrew Brookes of the International Institute for Strategic Studies.

Coffin of one of the dead
Flt Lt David Stead
Flt Lt Andrew Smith
Flt Lt Paul Pardoel
Master Engineer Gary Nicholson
Chief Technician Richard Brown
Flt Sgt Mark Gibson
Sgt Robert O'Connor
Cpl David Williams
Sqn Ldr Patrick Marshall
Acting L/Cpl Steven Jones

"Would those 10 men still be alive? I don't know. No-one is saying 'Had this been fitted, these lives would have been saved,'" he said, pointing to other recommendations in the inquiry report such as better intelligence.

The problem is wider than just one piece of equipment, he said, because the MoD is not spending enough on many things, including ships and tanks.

"We can spend money on armouring these planes but is it the best way to use resources?

"We've been flying Hercules in Iraq since 2003 and lost one, which is tragic. But when you crash a car, do you stop everyone driving?"

Every extra modification adds weight to the plane and restricts its mobility, he said.

And the installation of foam would mean taking each aircraft out of service, at a time when they are needed in Iraq and Afghanistan.

Cost could also be factor, although shadow defence secretary Liam Fox estimated the expense would be one one-off payment of 275,000 to the manufacturer plus 50,000 per aircraft.

A spokesman for Jane's Defence weekly said pilots were in a better position to assess whether foam would make a difference and it was interesting that they were saying it would.

1. Without foam: Explosive mix of fuel vapour and air above liquid fuel ignites easily. Once this ignites, a compression wave pressurises the remaining gas, increasing the explosion.
2. With foam: Foam expands to fill space in tank as fuel level drops. Vapour ignition is confined to the area close to spark, stopping explosion.

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