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Officials Say Short Circuit To Blame in TWA 800 Explosion

By Eric Malnic and

Ricardo Alonso-Zaldivar
LOS ANGELES TIMES -- WASHINGTON

The center fuel tank explosion that tore TWA Flight 800 apart and hurled it into the sea probably was ignited by a short circuit somewhere else in the plane that transferred excess voltage into the tank, federal officials said Tuesday. Although the blast and crash off Long Island on July 17, 1996, destroyed most of the direct evidence of exactly what happened, there is plenty of circumstantial evidence that such a short circuit occurred, National Transportation Safety Board officials said.

After four years of painstaking investigation, board experts have ruled out the possibility -- still promulgated by some -- that a bomb or a missile caused the crash that killed all 230 aboard the Paris-bound Boeing 747.Two days of hearings on the crash will conclude Wednesday with the board’s official conclusions about what caused the crash. There seemed little doubt Tuesday what those conclusions will be.

Bernard S. Loeb, director of the agency’s Office of Aviation Safety, told an audience of aviation industry representatives, news reporters and relatives of those who died in the crash that the agency’s investigation “leads to the inescapable conclusion that the cause of the in-flight breakup of Flight 800 was a fuel/air explosion inside the center tank.” The safety board had discussed such an explosion in a report issued five months after the crash.

Loeb said that exhaustive research and testing have ruled out a number of possible ignition sources, including lightning, static electricity and radiation from equipment like radar, cell phones and laptop computers. Also ruled out was a short in the electrical system that measures the amount of fuel in the tank, because it operates at voltages too low to generate a spark that could have touched off the blast.

Much more likely, Loeb said, is a scenario in which a high-voltage wire somewhere else in the plane shorted out one of the low-voltage wires in the fuel-measuring system. He said such a short circuit could have sent high voltage surging through the low-voltage wires to the tank, generating a spark large enough to set off the explosion.

“We cannot be certain that this, in fact, occurred. But of all the ignition scenarios we considered, this scenario is the most likely,” Loeb said.

NTSB engineer Robert Swain said that a number of factors support this theory.He noted that inspections of the 25-year-old plane that crashed and several other old aircraft turned up high-voltage wires on which the insulation was cracked and frayed.