On February 9, 1999, about 1515 Eastern Standard Time, a Hughes 369D, N5070J, was substantially damaged during a forced landing from a high hover, near Herminie, Pennsylvania. The certificated commercial pilot, and a passenger were not injured. A second passenger received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the aerial inspection flight that originated from Westmoreland County Airport, Latrobe, Pennsylvania. The flight was conducted under 14 CFR Part 91. According to Federal Aviation Administration (FAA) Inspectors, the helicopter was positioning next to a powerline tower, in a out of ground effect hover, so that the crewmember on the left rear skid could photograph a suspected damaged part. During the hover, the engine out warning horn sounded, alerting the pilot of a possible power loss. The pilot backed the helicopter away from the tower, lowered the collective, and turned to the left to avoid the tower. The pilot insured that the engine was at "max beep", and continued to maneuver the helicopter to a clearing along side the tower. Approximately 10-15 feet above the ground, the engine lost additional power, and the helicopter descended rapidly. Just prior to impact, the pilot applied maximum collective. The helicopter landed hard, on an approximate 20-30 degrees downslope, rocked forward, and came to rest upright on it's landing skids. During the rocking motion, the main rotor system came in contact with the tail boom, severing it about 1 foot aft of the tail boom attach point. After landing, the engine was shut down by the pilot, and he and two passengers exited the helicopter. Examination of the wreckage by FAA Inspectors revealed the helicopter at rest upright, about 300 feet from the base of the power line tower, on a heading of about 230 degrees magnetic. The power lines were oriented on a heading of about 230 degrees magnetic. The tailboom and tail rotor were found about 50 feet from the right side of the helicopter. About 150 feet from the right front of the helicopter, the vertical fin was found. Along the same line, at 300 and 400 feet respectively, parts of the tail rotor drive shaft were found. Three of the five main rotor blades were severely damaged, the remaining two were slightly damaged. The top of the transmission cowling revealed evidence of scraping by the main rotor. The flight controls were intact, with the collective in the full up position, and the cyclic displaced forward and left. All cockpit switches were in the "OFF" positions. About 300 pounds of fuel was onboard, and a fuel sample, taken about 15 hours after the accident, appeared to be straw-colored and clear, with no abnormalities revealed. The wreckage was removed from the accident site for further examination. On February 12, 1999, a FAA Inspector examined the airframe and powerplant at a maintenance facility. A visual inspection of the N1 and N2 rigging were performed, and determined to be in rig. An inspection and test of the fuel system revealed no abnormalities. The engine was then removed from the airframe, and both the turbine and compressor sections free wheeled by hand with no unusual noise or friction. On February 14, 1999, the engine and fuel controller were placed into a shipping container, then tagged and sealed by a FAA Inspector. On March 2, 1999, the engine was examined and tested under the supervision of a FAA Inspector, at the Rolls-Royce Allison Engine Company, Indianapolis, Indiana. The engine was examined by borescope, and then installed on a test cell. The initial start run up and power calibrations were nominal. The engine was accelerated from 70 percent to 95 percent torque, and no discrepancies were noted. The engine was shut down, and power calibrations were computed. The computed power calibrations revealed the engine was producing 12 percent more than rated power. The fuel controller was removed and transported to Allied Signal, South Bend, Indiana, without the permission or supervision of the FAA or NTSB. The fuel control unit was inspected and tested at Allied Signal on March 4, 1999, under the supervision of a FAA Inspector. No conditions were found that would prohibit the components of the fuel control unit from operating normally at the time of the incident. The winds reported by an airport located about 10 miles southeast of the accident site, at 1453, were 260 degrees at 9 knots.