I have had the Avistar since June of last year when I started. I have used the clamps on a OS46fx without any problems. Just make sure they are real tight. BTW: I have had many crashes, cartwheels, and a fun fly where I hit a fence twice, the limbo pole, and still the engine did not move. In all my other planes, the engine has been bolted in, but this one seems to be ok.