The Transportation Safety Board of Canada (TSBC) is devising tests to find out whether cockpit ceiling wiring from the crashed Swissair Boeing MD-11 suffered from electrical arcing before or after it was exposed to fire.

"Tests are under way to assess the significance of arcing found on 14 segments of wire from the accident aircraft," says the TSBC. It adds: "The TSB, in conjunction with a number of engineering laboratories, is working to develop a method to test whether the wires arced as a result of a short circuit in a normal environment or whether, instead, the arcing was a secondary outcome of a fire that damaged the wire insulation, which in turn allowed the wiring to arc. If a suitable test can be developed, the TSB will test some of the wire recovered from the wreckage of Flight 111."

Between May and the end of July this year an additional 2,000kg of wire bundles and aircraft skin, some of it from the cockpit area, was recovered from the sea off Nova Scotia, Canada, where the aircraft crashed in September 1998. The final phase of recovery operations will take place in mid September, says the TSBC, using a suction dredging ship.

Source: Flight International