THE Qantas jet engine that exploded on Tuesday after take-off from San Francisco had not been inspected after safety warnings issued two weeks ago.
The safety bulletins in Australia, Europe and the US had warned of ''uncontained'' engine failure - the technical term for when components are sprayed out of the engine enclosure during a malfunction.
The airworthiness directives were issued for Rolls-Royce RB211 engines, the model fitted to the Qantas 747-400 that was forced to make an emergency landing at San Francisco.
Qantas confirmed the jumbo's engines had not been inspected because it was not due for its regular maintenance checks. The engine that failed was last inspected on July 8. Some of the 212 passengers on QF74 reported seeing flames and sparks fly out of the plane's fourth engine about 20 minutes after take-off.
The explosion ripped a hole through the engine's cowling, causing the aircraft to shudder and requiring the pilots to dump fuel before making the emergency landing.
One passenger recalled seeing flames ''like a giant Roman candle stick'' shooting towards the back of the aircraft from the failed fourth engine.
Another passenger panicked and yelled, ''We're going to go down, we're going to go down','' but most handled the emergency calmly. Those who were not able to cope were ushered to the front of the aircraft.
Kirk Willcox, from Randwick, was seated in a row near the wing when he ''suddenly heard a loud pop and a swish'' as the fourth engine caught fire.
''We knew we had not hit turbulence,'' he said.
''We made a bit of a skid to the left, got the wobbles and then dropped in altitude.
''The girl I was sitting next to said, 'the engine is on fire', and I looked out and saw what looked like a giant Roman candlestick.
''It varied in intensity and was quite extraordinary.''
The airworthiness directive warned that ''several low pressure turbine shafts had been found with cracks originating from the rear cooling air holes''.
Qantas said that it was ''fully compliant'' with the airworthiness directive, which required that the engine be inspected the next time it was due for maintenance.
A replacement engine has been flown to San Francisco.