Thanks JNB, Yes, the investigator said the inside of the engine was completely demolished. The compressor wheel, only inches away from the power turbine, was intact meaning the impact did not cause the damage to the power turbine wheel. The inside of the exhaust was riddled with pings from the inside out as the pieces of broken turbine were extruded through it. He said there was no "kink" in any part of the power portion or linkage (not sure I am saying that correctly) of the engine as would be expected if the engine was running and then suddenly stopped on impact. The investigator said it is "textbook 101 power turbine wheel failure" This had to have a major impact on the takeoff. Whether my son got frantic and made mistakes after that remains to be seen. We may never know. All I know is that he was a good pilot and I was so proud of him. I wanted to learn more about what happened and I have. Thank you everyone and I will let you know what transpires in the future with the litigation. I admire you pilots and wish you safe flying.