On September 14, 2015, about 1530 central daylight time, a Robinson R44 II helicopter, N442CF, registered to Alice Environmental Services LP of Alice, Texas, sustained substantial damage after a hard landing while conducting a practice autorotation maneuver. The local flight was being conducted under the provisions of Federal Aviation Regulations part 91. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed throughout the area and a flight plan was not filed. The flight had originated from the King Ranch, Alice, Texas, about 1445. The pilot reported that he was flying the helicopter to practice emergency maneuvers. After two successful power recovery practice autorotations, he was setting up for a third. On the third attempt, he decided to maneuver the helicopter to a specific spot on the ground, flare, then terminate in a hover. He stated that everything went great until the flare. There was a vibration in the rotor, and instantly the pilot tried to power recover, but the "power wasn't there." At this point, the pilot leveled the helicopter and used remaining collective to soften the landing. Upon contacting the ground, the helicopter separated from the skids and rolled onto its side. Both the pilot and the passenger exited the helicopter uninjured. The passenger stated that the previous two practice autorotations went well. He stated that during the third autorotation, when the pilot he started to throttle up, he did not hear the sound of the engine revving up and the governor taking over. He stated that it felt as if the helicopter wobbled left and right before landing. He stated that the helicopter hit the ground level, bounced, and rolled onto its left side. The rotors made contact with the ground. He had expected to hear the sound of the engine, but he did not. The FAA inspector that examined the wreckage at the accident site reported that both skids were fractured away from the helicopter. On main rotor blade was fractured in half and the fuselage was buckled. Inspection of the airframe and engine did not reveal any mechanical anomalies with the airframe or engine, other than impact damage.