This is pulled from the following link:
NOTE: Thunderbird controllers are NOT for use in helicopters. Please use a Phoenix controller for heli applications.
http://www.castlecreations.com/produ...nderbirds.html
I don't think the BEC in the cheaper Thunderbirds can handle the number of servos and the gyro in a heli. If you ad an external BEC you maybe can continue to use the T-bird.