An American Airlines jet engine that failed seconds before takeoff in a fiery runway accident at Chicago’s O’Hare International Airport flung broken turbine parts as far as a kilometre from the scene.

Disclosure of the “uncontained engine failure,” in which internal parts breach the protective housing designed to keep them safely enclosed, came a day after a mishap that authorities said neared the point of disaster.

Shrapnel escaping from the engine’s outer cover can tear through the cabin or rupture fuel tanks in the wings.

Such “uncontained” failures are extremely rare, and National Transportation Safety Board investigators were looking for clues as to whether the fault lay with the engine itself, with its manufacture or a freak event such as debris on the runway entering the engine.

The General Electric engine that powered the plane was a workhorse model known as the CF6, introduced decades ago, GE spokesman Rick Kennedy said.

The American Airlines plane engine dates from the 1980s or 1990s, and had been serviced by the airline, he said.

American Airlines Flight 383, a twin-engine Boeing 767 bound for Miami with 161 passengers and a crew of nine, was headed down a runway for departure on Friday when the right-side engine failed.

It forced the crew to abort takeoff seconds before the plane was to have become airborne.

Leaking jet fuel caught fire under the wing, as the crew evacuated passengers via emergency exit chutes from the left side of the plane.

Fire crews arrived to begin pouring foam on the flames within minutes.

One flight attendant and 19 passengers suffered minor injuries in their escape, and authorities said flames never breached the plane’s cabin.

In a sign of the intensity of the engine breakdown, at least two pieces of a stage-2 high-pressure turbine disk were flung from the scene.

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The Federal Aviation Administration said in a statement that while the Boeing 767 was taking off about 2.35pm local time bound for Miami, the pilots reported the tyre problem and aborted the take-off.

One passenger, Ian Jones, spoke to Miami’s 7News shortly after being evacuated from the plane.

“We were sitting there and obviously were about to take off because it was getting to the point where you couldn’t get out of your seat. And then, all of a sudden, a loud pop and flames and flames and flames,” Jones said, “and then panic and just chaos.”

“When the pop occurred, everybody pretty much just panicked immediately,” Jones said,

“There wasn’t much instruction. Everybody pretty much just rushing, trying to find an exit, and once an exit was found it was still chaos. There was literally not much direction from the staff.”