On April 11, 1999, about 1645 eastern daylight time, a MBB BK 117 A-3, N163BK, registered to and operated by Rocky Mountain Holdings, LLC, as a Title 14 CFR Part 91 EMS positioning flight, collided with a building while hovering in preparation for takeoff at Sarasota/Bradenton International Airport, Sarasota, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the commercial-rated pilot and two medical personnel flightcrew members were not injured. The flight was originating at the time of the accident. The pilot stated they were on an EMS flight to Charlotte County Airport, Punta Gorda, Florida, to pick up a patient. He and the other flightcrew members boarded the helicopter and he lifted it into a hover facing south. He called the FAA Sarasota Control Tower for departure clearance and the controller asked him to hold for landing traffic. The controller then asked if he could see the landing traffic. He moved the helicopter to the east, looking for the traffic. He then heard and felt a "thud" followed a second later by three more "thuds". It appears the helicopter had drifted back and the tail rotor had contacted the hangar. He maneuvered the helicopter away from a culvert and landed next to his original parking spot. After exiting the helicopter, he noticed the tail rotor was damaged along with the landing gear. The hangar also had a 3-foot by 3-foot hole in it.