The Federal Aviation Administration said last night that it will order U.S. airlines to inspect thousands of jet engines to ensure that the problem suspected in last week's aircraft fire in Manchester, England, does not recur.

FAA spokesman Fred Farrar said that "we do not expect the inspections to be disruptive to U.S. airline schedules."

Fifty-four passengers died in Manchester when the left underwing engine of a British Airtours plane burst into flames as the aircraft was starting to take off. The pilot braked the plane to a halt, but the quickly spreading fire and at least two fuel-fed explosions trapped many passengers in the rear of the plane.

The engine, the Pratt & Whitney JT8D, is the most widely used jet engine in commercial service. It is the powerplant not only for the Boeing 737-200 involved in the Manchester fire but also the Boeing 727 series and the McDonnell Douglas DC9 series. Those three aircraft constitute about two-thirds of the U.S. major airline fleet of 3,000 planes and power 95 percent of the nonjumbo jetliners in the world.

The FAA is following the lead of the British Civil Aviation Authority (CAA), which yesterday ordered urgent checks of JT8D engines on its aircraft. The CAA said that some British-operated planes would be grounded until inspected and that others on the Continent would be flown to Britain for inspections.

The CAA said that "preliminary investigation of the Manchester Boeing 737 accident indicates that combustion chamber deterioration could have caused overheating of the combustion chamber outer casing, leading to its failure.

"Subsequent checks made into engines have revealed various combustion chambers with extensive cracking to the cooling rings and chamber heads."

Nine combustion chambers, which look somewhat like portable fire extinguishers, are located in the middle of JT8D engines. Air enters an engine, is compressed and fed to the combustion chambers, where it is mixed with fuel and ignited. Exhaust gases provide thrust and pass through a turbine to rotate the compressor.

Investigators think that one of the combustion chambers on the 737 blew apart and shot a piece of chamber wall through an underwing maintenance access panel into a fuel tank, starting the fire.

FAA officials said the British have a schedule somewhat different from U.S. airlines for inspection and replacement of combustion chambers. The U.S. inspection order will be issued "after we have determined what is appropriate, given the differences," Farrar said.

The CAA order said that the inspection schedule would vary from engine to engine, depending on how it had been used and inspected.

Jim Linse, a spokesman for Pratt & Whitney, said that "in response to the CAA order, we will assist all operators until the cause of the accident is determined."