On December 7, 1993, at approximately 1355 Pacific standard time, a Hiller-Soloy UH-12D helicopter, N2297W, sustained substantial damage when it collided with terrain during an autorotation after the loss of power. The commercial pilot, who had been conducting christmas tree hauling external load operations near Sublimity, Oregon, under 14CFR133, was not injured. No flight plan was filed for the local flight, and weather was reported to be visual meteorological conditions at the time of the accident. There was no ELT installed in the aircraft, and no fire occurred. The pilot stated that he had shut the aircraft down, and proceeded to grease the aircraft and add engine oil. After greasing, he noticed the fuel truck had been moved and the refueling hose secured. He said he assumed that the helicopter fuel tank had been refilled and did not check. He entered the cockpit and set the timer to 80 minutes and restarted the lifting operation. Thirty-six minutes into the operation cycle, the engine-out warning system activated with subsequent flameout. He released his load and descended to a hard landing. The aircraft bounced on ground contact and rolled to the left. The pilot stated that the cause of the flameout was fuel exhaustion due to the lack of fuel. He also noted that the pilot should not assume that ground support personnel faithfully perform their functions, and that the PIC must perform adequate preflight to include assurance that his aircraft has been refueled. FAA inspectors stated that the fuel tanks were bone dry, and when the battery master switch was turned on, the fuel gauge indicated zero.