i have a pilatus pc-9 and i had found out on my first few flights that mine does the same thing. i found that i have to get up to full speed before takeoff. The pc-9 doesn't like low air speed or slow landings. on take off don't give it to much elevator or it wll snap right off the bat. Just ease on the elevator until it comes to a 15 degree angle and continue to clime and build air speed. When you have done that you will find that the pc-9 will become very stable in the air until you come to a stall and move the aileron left or right it will go into a snap and then to a spin.
hope you have luck. crashed mine 3 times 4 repairs. finally got to fly it 6 times and as long as i had good air speed it is a smooth flying plane. I also found that you will need to reglue the wing servo trays and run a bead of ca on the rest of the servo trays.
hope you can tame that plane good luck.

If we didn't crash em it wouldn't be a hobby