The company and engineers accused of negligently causing a Concorde supersonic jet to crash outside Paris with the loss of 113 lives were to go on trial for a second time on Thursday. A previous prosecution after the 2000 disaster found US carrier Continental and one of its employees guilty of allowing a sliver of metal to fall from one of its jets onto a runway, where it burst the tyre of an Air France Concorde. But four French defendants were cleared -- in a 2010 ruling that Continental denounced as French \"protectionism\" -- and prosecutors demanded a second trial at which all six accused parties will once more face prosecution. The trial was to begin in Versailles, outside Paris, on Thursday and continue until May 9, as judges reconsider technical evidence about the 12-year-old crash and the design and safety record of an obsolete plane. But the hearings could yet been postponed or abandoned if defence lawyers working for the French defendants successfully argue that a retrial on the same charges that they have already been cleared of is unconstitutional. One of Air France\'s supersonic jets, a triumph of Franco-British engineering and long a symbol of transatlantic luxury travel, burst into flames shortly after take-off north of Paris on July 25, 2000. In all 113 people were killed, all 100 mainly German passengers and nine crew on the New York-bound flight and four people on the ground in the Paris suburb of Gonesse, where the burning wreckage smashed into a hotel. The first trial came to an end in 2010, with Continental Airlines and one of its employees found guilty of negligent maintenance in allowing a 40cm (16 inch) blade of metal to fall from a DC10 jet onto a Charles-de-Gaulle runway. This was said at trial to have pierced the Concorde\'s tyre, causing it to burst and damage a fuel tank in the plane\'s wing, triggering in turn a leak and an explosion that destroyed the jet in flight.Continental\'s lawyers denied this, insisting that witness testimony showed the jet was already on fire when it passed the point where the metal had fallen. And lawyers for the victims accused airlines and safety authorities of ignoring what they alleged were longstanding design flaws in the jet. But judges at the first trial found Continental guilty of negligence, fined 200,000 euros and ordered to pay a million euros in damages to Air France, which had previously compensated the families of the dead passengers. It also convicted 44-year-old Continental engineer John Taylor of negligence in using titanium to construct the defective metal strip that fell from the DC10, arguing that this was a unsuitable material. He was given a 15-month suspended sentence. His supervisor, 72-year-old Stanley Ford was cleared, despite admitting he had failed to inspect the suspect repair. Three elderly French aerospace executives were also tried and cleared. Henri Perrier, 82, directed Concorde\'s test flights from 1976, and was head of the jet\'s programme at plane-maker Aerospatiale until 1994. He denied ignoring evidence of a weakness in Concorde from a 1979 accident. Perrier\'s lawyer said he would not attend Thursday\'s hearing due to ill health, and called for the case to be dropped. Jacques Herubel, 76, worked as an engineer for Perrier between 1993 and 1995. He was also cleared of negligence in the previous trial. Claude Frantzen, 74, held several senior positions in France\'s DGAC air safety authority between 1970 and 1994. His lawyer will argue that he cannot be tried on the same charge twice. The Concorde has since been taken out of service by both British Airways and Air France and the era of supersonic air travel has come to an end.