[QUOTE]Considering the damage which was found on the No. 1 engine fan blades, the LP compressor and the HP compressor, there can be no doubt that the engine ingested a hard-bodied object. Laboratory analysis of the impact sites revealed consistent traces of debris similar to low carbon steel (typical of mild steel). Impact marks suggest that the object may have been of round shape with a diameter of 25 mm.[/QUOTE]
Reminds me of the story some years ago of a Citation which lunched the left engine on rotation when the door key passed through the intake. The newbie F/O had unlocked the door for his Captain and closed the door after the pax boarded.
The typical round-headed aircraft door key is made of mild steel and measures about 25mm across!
Circumstances not quite the same, but, Hmmm....