On June 28, 2000, about 0730 mountain daylight time, a Hughes 369D, N8653F, registered to and operated by Thomas Helicopters as a 14 CFR Part 137 aerial application flight, collided with the terrain following a loss of engine power near Heyburn, Idaho. Visual meteorological conditions prevailed at the time and no flight plan was filed. The helicopter was substantially damaged and the commercial pilot, the sole occupant, was not injured. The flight originated from Gooding, Idaho, about 2 hours prior to the accident. In a written statement, the pilot reported that the day before the accident, he had the flight crew put in 300 pounds of fuel. Verification of fuel quantity was made via the helicopter's fuel gauge. About 30 to 40 minutes prior to the accident, the pilot had the flight crew put in another 150 pounds. While flying about 70-80 feet above ground level spraying an insecticide over a residential area, the audible engine out warning sounded and the engine lost power. The pilot turned the helicopter to the right and had to extended the glide to clear obstructions for the emergency landing in a field. Just prior to touch down, the tail rotors struck low growth spruce trees. The helicopter touched down hard in the field, partially collapsing the landing skids. The main rotor blades struck and severed the tailboom. During the post-accident on-site investigation by a Federal Aviation Administration Inspector from the Boise, Idaho, Flight Standards District Office, the inspector reported that he checked the operation of the "fuel level low light" which at that time did illuminate. He also noted that the fuel quantity gauge was indicating empty. Approximately one pint of fuel was drained from the fuel system. The pilot reported to the inspector that he did not see a "fuel level low light" prior to the engine failure. The helicopter was removed and taken to the owner's facility in Gooding, Idaho. There, the helicopter was positioned for a level flight attitude. Approximately one pint of fuel was drained from the fuel tank. No leaks from the fuel hoses or seals were confirmed. Two tablespoons of fuel remained in the fuel supply hose to the fuel nozzle. A measured fuel quantity was supplied, then removed from the system to test the accuracy of the fuel gauges and warning system. The tests confirmed that the fuel-sending unit indicated more fuel on the fuel gauge than was actually on board. The low fuel warning light also did not illuminate properly every time. The pilot reported that the company's fuel truck does not have a metering system. The fuelers use a "12-second" fueling burst which is estimated to be about 150 pounds of fuel. The fuelers also are supposed to confirm that the aircraft fuel gauges moves.