Tunning an engine from the front is a habit that I never got into. Guess because i needed to stand behind it and hold the plane down as i tuned it.

I did see a guy at our club with a OS .70 FS tunning in front of the engine. The engine came off the firewall the spinning prop tore into his stomach. He immediately collapsed and was rushed to the ER. He ended up getting over 250 stitches and had to over come a infection from the fuel also.

I know it is not very often to see an engine completely come off but can happen. Another thing to keep in mind is to check the screws before the each flight.