Yesterday's Air France Concorde crash near Paris has focused attention on engine failure as the most likely scenario.

Yesterday's crash in Gonesse shortly after takeoff from Paris Charles de Gaulle International Airport, killed all 100 passengers, nine crewmembers and four people on the ground. The smoke and flame jetting from the left side of the Concorde extended at least 200 feet. The aircraft carried Serial No. 3 and was the first production Concorde. It had accumulated 11,985 hr. and 3,978 flight cycles.

The Olympus 593 engine, made jointly by Rolls-Royce and Snecma, is a derivative of a Bristol-Siddley engine that was conceived for the British Vulcan bomber. It uses 1950s engine technology. Rolls-Royce bought Bristol-Siddley in the 1960s.

Rolls had a 60% share of the Olympus program and was responsible for the hot section. Snecma made only non-moving parts on the engine.

Because only 14 Concordes entered revenue service and the Olympus partners had stockpiled a large supply of spares, no parts have been made for years. So although the Concorde's engines are carefully maintained and inspected, there have been no improvements to their technology. In addition, the spares are aging even as they sit on a shelf.

Investigators will want to determine whether the crash was caused by a single engine failure or whether the initial failure damaged the adjacent powerplant.

John Wiley, a USAirways captain and training pilot who recently "flew" British Airways' Concorde simulator wrote in Aviation Week's Show News that he doubted a single engine failure was responsible. "It is always dangerous to speculate about air crashes from the 2.5 hr. I had in the simulator, (but) I doubt it. We were able to sample the handling with various engine failures from single engine failures at V1 to dual engine failure at Mach 2.0. With the V1 engine failure, the Concorde showed better than average manners."

Neither engine maker would discuss the accident yesterday.

"We have started gathering the known facts of the incident," said Christopher Springham, Rolls-Royce director of media relations. "We will not speculate on the facts of the crash because it's premature. A board of inquiry has been established, and we cannot give out any information on the status or history of the engine or airframe."

Parallel investigations will be conducted in France. The French accident investigation bureau or BEA will search for the technical causes of the accident. British accident investigators also will join the probe under terms of an agreement between the two countries. The second probe will be a judicial one that will attempt to determine who is responsible for the accident.

Because the flight, which carried German tourists on a charter flight bound for New York, investigators from Germany and the U.S. National Transportation Safety Board also will participate in the probe.

By Mike Lavitt