Hi 4 stroken ron,

>>Why not just kill the engine by closeing the carb with the throttle servo?

I think everyone does that, but the point is having a backup method to kill the motor. What about if the throttle linkage breaks, or jams? How about if you have radio interference that just affects the throttle? Don't laugh, this just happened to me, and it was the first time in ages I hadn't installed a back up method to kill the motor because I was trying to save some weight. The plane was within 10 feet, or less, pointing right at me as I taxied off the runway and the throttle went to full. I had just enough time to get it turned and take off again.... uncontrolled. Ok, you can laugh now. I was lucky and the throttle servo unlocked and I was able to land(quickly and roughly), but I wished I had had another way to kill the motor.

It wouldn't have been so bad in this case if I hadn't been lazy and not setup my failsafe settings. The default failsafe is last position, which isn't the best thing for the throttle. If I had set it up to go to idle for failsafe(as I usuallly do) it would have been a non-event. (FYI, it turned out I had a loose ground strap on the ignition causing the interference)

Bill