Oh no! It's going to crash, the rotors have stopped turning!!! Wait. That's just your shutter speed. He-he. Nice job of stopping the motion. You've managed to take an image of an aircraft WITHOUT centering it in your composition. Hooray! Good to see that. Even the top of the tree helps here as it adds context to the image. Others will find that tree top distracting I imagine, but hey, this IS DPChallenge. ;^) Color in the sky seems off, but it may be the time of day? Good luck.
Another chopper shooter! Big machine, makes the 500D I run around in look like a mini! Is that a female pilot??
Anyway, as someone who takes alot of pics of choppers, I know how difficult it is to capture them; job well done. However, itd be nice to have the whole chopper in the shot. Otherwise, good job on a shot that looks like it was taken in less than ideal conditions.