On February 26, 2000, at about 0216 central standard time, a Bell 412, N411UT, registered to University Health System Inc., operating as a 14 CFR Part 91 air ambulance positioning flight, experienced an in-flight collision with a tree with maneuvering at a road side landing zone (LZ). Visual meteorological conditions prevailed and a company flight plan was filed. The helicopter sustained substantial damage. The airline transport pilot, flight nurse and emergency medical technician reported no injuries. The flight originated about 15 minutes before the accident. The pilot stated he landed at an LZ to pick up injured personal. The slope was of the terrain was too steep, so he decided to reposition the helicopter and picked up to a hover. He was looking out the left side of the helicopter watching wires next to a driveway. He turned the tail to the right and the tail rotor collided with about a 15-foot-tall tree. There were loud grinding noises and the helicopter yawed to the right. He reduced collective and the helicopter came to rest on the skids.