On June 19, 2011, about 0720 Pacific daylight time, a piston engine-powered Hiller UH-12E helicopter, N138HA, experienced a hard landing in an agricultural field near Lost Hills, California. The commercial pilot, who was the sole occupant, received minor injuries, and the helicopter, which was owned and operated by the pilot, sustained substantial damage. The 14 Code of Federal Regulations Part 137 aerial application flight, which departed a local refueling site about 15 minutes prior to the accident, was being conducted in visual meteorological conditions. No flight plan had been filed. According to the pilot, after making a spray pass during which he applied chemicals to an agricultural field, he ascended to about 100 feet above ground level (agl) in order to make a downwind turn. At that time the helicopter's engine suddenly stopped producing power. Because of his height above the ground, the pilot immediately entered an autorotational descent in order to attempt a forced landing. According to the pilot, during the landing sequence, he applied up collective in order to slow the descent rate and initiate the landing flare, but the main rotor blades ran out of energy to produce lift while the helicopter was still about 10 feet above the ground. It therefore landed hard in an alfalfa field, and the impact resulted in substantial damage to both the main rotor blades and the airframe. A postaccident teardown inspection of the helicopter's fuel system determined that the engine driven fuel pump could not be turned by hand, that its internal metallic surfaces were galled, and that it was contaminated with loose metal particles. The inspection also determined that the 24 volt-powered auxiliary fuel pump had failed and could not be turned by hand.