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TSB finds ignition spot (arcing)on IFEN wiring
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posted
Saturday, March 29, 2003 Back The Halifax Herald Limited

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Swissair investigation 'tremendous success'
Team proud of effort that found cause of crash
By Alison Auld / The Canadian Press

It must have seemed like an impossible task: a plane sitting in two million pieces on the ocean floor and, somewhere in the splintered remains, a reason why it hurtled from the sky.

But within hours of Swissair Flight 111 plowing into waters off Nova Scotia, Larry Vance and Vic Gerden began an obsessive search for answers.

Vance, an aviation investigator with the Transportation Safety Board, was watching the news on Sept. 2, 1998, when he heard a jetliner had gone down and that there were likely no survivors.

For most of the night, he was on the phone to colleagues like Gerden, making plans to get to Halifax and begin what would become one of the country's most complex and difficult aviation investigations.

"When we started off we knew it was going to be a huge project, but I don't think we knew until we were into it by a number of weeks or maybe even two or three months just how huge it was going to be," Vance said Friday in Halifax, a day after the board released its final report into the disaster.

Those efforts spanned 4� years, in which a small team of specialists from various agencies spent seven days a week sifting through mangled debris in the hunt for an elusive cause.

For Gerden, it meant a prolonged separation from his family that will only end in the coming days when he returns home after being based first in Halifax and then Ottawa.

"I'm looking forward to a shorter work week and more time with my family," Gerden, the lead investigator in the case, said from one of many hotel rooms that have been his home in recent years.

On Sept. 3, he packed his bags and headed east from his Winnipeg home. He then hunkered down in a hotel and the sprawling hangars in Shearwater where pieces of the MD-11 were being stored.

Gerden spent his days shuttling between sites, examining different pieces of wreckage for clues as to what caused the jetliner to suffer a catastrophic power failure just over an hour after it left New York for Geneva.

The answers didn't come immediately, but there were indications in the first couple of months that the plane's wiring played a crucial role in a fire that seemed to have been concentrated above the pilots' in the cockpit ceiling.

"That was a major task to go through the couple hundred kilometres of wire that was in small pieces, and try to identify those pieces of wire that belonged to the front part of the airplane," Gerden said in an interview.

From shattered bits, some the size of a quarter, they managed to retrieve wires that showed damage caused by arcing, a phenomenon in which the wire's outer lining becomes chafed or corroded and sparks can ignite.

Piece by piece, the team worked to craft a sequence of events that could explain why the pilots began smelling a strange odour 53 minutes into the flight, and then minutes later lost communications and control.

Months later they moved from the hangars to labs in Ottawa, where they had to develop new computer-modelling programs to understand what happened. They subjected various materials to ignition sources to see how they performed. And they did a descent profile to discover that the plane got locked into a right-banked turn with a 20-degree list at a speed of 560 kilometres per hour before hitting the water.

Their focus turned to a flammable insulation material that lined the cockpit cabin, which they concluded allowed the fire to spread rapidly from the pilot's overhead area to outside their cabin.

Eventually they linked it together, showing that arcs on at least two pieces of wire were fanned by the highly flammable blanket insulation - a conclusion they're extremely proud of reaching given the complexity of the case.

"That's a tremendous success," says Vance. "When you look at starting with a couple million pieces of airplane on the bottom of the ocean and you end up finding an arc that was almost too small to see with the naked eye . . . our satisfaction is very, very high."


http://www.herald.ns.ca/stories/2003/03/29/pNovaScotia212.raw.html
 
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