It's called Rotors Field. It's an FSX only airport! I have just put up the BETA VERSION. If you fly helicopters, this is your airport. Go here to download it from my website.
The airport has a few things to keep you entertained for quite a while. There's a dirt runway to practice autorotations with a brick wall at the end if you don't stop in time, a pond for practicing filling bambi buckets or water drop tanks, and cones for practicing maneuvers.
Enjoy,
-Brandon