TWA Flight 800 sustained an explosion in the centre fuel tank area, but it was unclear if that was the primary explosion which brought the aircraft down or a secondary blast, the leading investigator has said in New York.
The Paris bound Boeing 747 exploded and crashed into the Atlantic Ocean off Long Island, New York, on July 17th, killing all 230 people on board.
Mr Robert Francis, vice chairman of the US National Transportation Safety Board, said in an interview on CNN yesterday that evidence such as the condition of the seats over the centre tank showed an explosion occurred in that area.
"We've decided we can say that, and how it came about ... whether it was primary or secondary or whatever is part of the remaining puzzle that we haven't put together yet," he said.
Investigators have said there was no definitive evidence to indicate whether a bomb, missile or mechanical failure caused the disaster.
Mr Francis said another body had been found, bringing the total of those recovered to 209. He said he hoped more bodies would be retrieved as the recovery vessel Grasp was still working over an area that contained a lot of wreckage.
"One hates to be too optimistic and one doesn't want to get people's hopes up too much, but I think as long as we're dealing with a major area of wreckage which is still under Grasp, that there's hope we'll find some more," he said.
He said he was uncertain how long it would take the Grasp to bring up the wreckage.
Mr Francis said in a CNN interview on Wednesday that the noise heard on the cockpit voice recorder was unlike the noise detected when Pan Am 103 blew up over Lockerbie, Scotland, in 1988 or in other aircraft disasters.
Mr Francis said experts in Washington did not expect to learn anything more from the cockpit voice recorder or the flight data recorder.