I have a similar problem with the mission, every time i want to play the mission i can't get further than the formation flying.
Cause every time just before the other helicopter is shot down (yeah i reached that point once, but after the autosave it went wrong) i make a normal turn to the right/left and my rotorblades just stop and i can't get them working again before i crash.
I hope anyone knows a solution to this problem.