Wow. Close call.Well the most butt puckering event while flying in quite a while happened today. Lunch time flying with a buddy and he brought out his Muscle Coupe and said you wanna fly it? And who says no to flying a beauty like that. About two minutes in I do a nice power off down line, pull straight and level about 20' up and begin to throttle up. As soon as I do it begins to shake violently and ejects the hatch. no matter how much throttle I gave it, it would seem to get any more than 1/4 throttle but I did manage to nurse it around and safely land it. as soon as it stops the prop and spinner are wobbling bad and we think the motor has come loose. Instead we find the prop nut had come off. How it didn't eject the prop is beyond me but I'm glad it didn't or the plane would have ended up in the middle of a rough field. Shook lots of stuff loose so he needs to do some repairs but man oh man did it make me pucker up.