Pieces of two oxygen cylinders carried in the cargo hold of ValuJet Flight 592 were found imbedded in a spare tire carried as cargo, strengthening suspicion there was a fire or explosion during the flight, a federal investigator said Sunday.
National Transportation Safety Board investigator Greg Feith said the plane carried 136 of the oxygen generating canisters in its cargo hold, more than twice as many as previously thought. He said inspectors knew of only 15 that had been discharged before they were placed on board.The ValuJet DC-9 plunged into the muck of the Florida Everglades May 11 shortly after taking off from Miami, killing all 110 aboard.
Feith, who said previously there may have been an explosion aboard the plane, said the pieces lodged in the tire came from two different canisters. He refused to speculate whether they had exploded.
"They did show evidence of stress in that they were bent and twisted. They did have some evidence of heat distress," Feith said. "To what extent they distributed it or caused it, there's no way to tell that at this time."
The canisters were removed two or three months ago from three ValuJet MD-80 aircraft that remain in service. They were were being carried back to the carrier's Atlanta headquarters for refurbishment.
The canisters are attached to plastic face masks that drop from the airplane ceiling, allowing passengers to breathe if cabin pressure is lost. They are activated by pins that trigger a chemical process to produce oxygen.
Feith said the canisters were stored in boxes marked "company material," but it was unclear whether the ValuJet employees who loaded them onto the doomed plane understood how volatile they were.
He said search crews would use ground-penetrating radar to map out the crash site and pinpoint wreckage buried under the muck. The search will focus on the canisters and the cockpit voice recorder that may contain the pilots conversation in the final minutes before the crash.
Search crews also hope to find a circuit breaker panel located behind the captain's seat. Problems with that panel delayed the plane's Miami-bound flight out of Atlanta earlier on the day of the crash.
The experimental low-level radar, which has been used to locate buried dinasaur bones and Egyptian tombs, has already located several objects buried in the muck, including part of a wing.
Feith said an independent contractor would be hired by week's end to bring up the larger parts. During the weekend more of the crew's possessions, parts of the tail section, insulation, ceiling material and a metal chair track that showed evidence of soot damage were recovered.
Workers have used a heavy-lift helicopter to remove debris from the muck, carrying it by truck to an airport hangar for inspection. They have still recovered less than 10 percent of the craft.
Newsweek magazine reported Sunday that Federal Aviation Administration computer records showed inspectors had opened 43 "enforcement investigations" of ValuJet, including nine involving maintenance. But FAA safety chief Anthony Broderick told the magazine the agency had destroyed original records of some of those, which it does with minor infractions.
The magazine said it had gathered information, mostly from FAA files, showing that ValuJet planes were involved in 12 "accidents" and less serious "incidents" since January 1994, including botching a landing so badly the plane landed with no nose gear.