DozyWannabe:
...caused the NTSB to have their lead investigator hold a press conference which identified a broken engine mounting bolt as the primary causal factor of the accident before their metallurgist had been given a chance to inspect it. Before long, it became apparent that the bolt had fractured on ground contact, which caused the agency considerable public embarrassment when they had to make another announcement that they were wrong.
It's actually a bit more embarrassing than that.
Ravenswood Airport was right on the NW boundary of ORD, and while it had been closed for some time, there was still a hangar containing parts for light aircraft. The DC-10 ploughed into that old hangar.
The broken bolt was actually a Cessna or Piper part.
And the official who made this bogus pronouncement was Vice Chairman of NTSB, E. T. Driver