Thanks for the info - may be my setup then. Will take another look at throttle hold value. Can't think what else it could be (also on a Trex 150 but with non-standard escs).
Thanks Kluftinger - I'm using a heli version of blheli in the tail esc but but don't think there's any settings that would cause the tail to spin up at full speed when throttle hold is on. It seems the uSpirit doesn't detect that throttle hold is on.
Ok will go over everything again. What should the throttle value be on the monitor page when throttle hold is on? Mine shows -0. Should it be lower than that?