By Alison Auld / The Canadian Press

Lawyers representing dozens of families who lost relatives in last year's Swissair plane crash filed a $3-billion US lawsuit Wednesday against a giant U.S. chemical manufacturer.

Lee Kreindler, a Manhatten lawyer for 76 victims, said a 49-page suit against Du Pont was filed in a New York City court Wednesday afternoon.

The suit names Du Pont as the manufacturers of metalized Mylar, insulation that was used on the Swissair jetliner that crashed off Peggys Cove last Sept. 2, killing all 229 people on board.

"It's a substantial factor in the spreading of the fire," Kreindler said from his office. "That is tantamount to probable cause."

The U.S. Federal Aviation Administration issued a directive last week that said the insulation, found in the plane's bulkheads, should be removed from a series of planes made by McDonnell Douglas.

The order, which affects more than 1,200 planes worldwide, was based in part on the findings of an investigation into the crash by Canada's Transportation Safety Board.

The TSB said the Mylar failed flammability tests and that "a significant source of the combustible materials that sustained the fire was thermal acoustical insulation blanket material," or Mylar.

The Swissair pilots reported smoke in the cockpit moments before the plane went down. Investigators haven't determined the cause of the crash, but have focused on possibly faulty wiring.

Kreindler's cases against Swissair and Boeing Co., which owns McDonnell Douglas, are valued at $25 million in compensatory damages and $25 million for punitive damages for each of the 76 victims. If successful, they could be the largest lawsuits in aviation history.

His firm was also trying to determine which company made the blanket insulation that contained the Mylar so it can sue it.

"If we could identify the manufacturers of the blankets, we would sue them, but it doesn't look like that's going to happen," he said.

The suits had to be filed within the first year of the crash because of certain statutes in Nova Scotia and the United States. Lawyers for three other families filed suit against Du Pont in a California court earlier this week.

The FAA order must be carried out within four years and could cost up to $880,000 per plane. Swissair and Boeing have offered to accept financial liability and pay compensation. But they are trying to get the non-American cases tried where the ticket was purchased. European courts traditionally hand down smaller awards.