I think Blackwater Helicopters may be.
Speaking of which , I saw some clips of them on the weekend on
www.youtube.com.
Just in the search function put "blackwater" and on the left hit search by rating...some interesting flying clips there.
Especially the one where the guys in the 500 pop up on the corner of the building where the guys with the machine gun are at , knock them to the ground with the skid , clear their table of items ..with the skid & then give them the finger on departure......
If they are not operating I am sure they would know who is & details....looks like they had around 5 odd 500's there.
HF