ORIGINAL: jedijody
All very good information TOM and I agreebut in this case it seems clear the engine stopped then the prop exploded. I've seen engines shed props and none of them quit like that, they kept running and suffered no damage if the operator shut them down fast enough.
Why is it I've never heard what an engine sounds like while running with loose propeller bolts,.... no, I don't think I'll experiment with that one. [8D]
I have heard a 150 get started with loose prop bolts. The owner of the airplane started to put the prop on the airplane then was distracted by spectators at the feild. Forgot the bolts were only hand tight and put the spinner on. I was holding the airplane and it was obvious. It sounded as if something was tapping the muffler. The engine was not reved but by the time I convinced the owner to shut it down the prop bolts were pretty much gone. Some sheared before shut down some at shut down. All bolts were bent. Early on the OP stated he had only tightened until the lock washers were compressed. Way short on torque. Could it have been that when the prop let go the press fit on the two peice crank slipped and that is what jammed up the engine? I would assume the stresses on the crank with only half a prop could cause the press fit to slip. I once saw a 40% composite airplane get mid aired and shed 1/4 the prop and it shook so hard the wings were actually flapping and the airplane shed parts all the way to the ground.