Mine was due to mechanical failure. The crash occurred about 30 seconds after takeoff. my speculation is that the horizontal stabilizer came loose, resulting in the pushrod pushing and pulling the entire stabilizer instead of deflecting the elevator. My friend Dave noticed that it was loose when we were setting up, so we CA'ed the wood stabilizer to the plastic fuselage. hey, the stuff claims to work on plastic. he then flew his plane. about 20 minutes later we tried to fly mine. I should have waited an hour, but i forgot the total cure time for the CA was 1 hour. I guess the maintenence dept screwed this one up!