On June 28, 2010, about 0817 mountain standard time, an experimental amateur-built Worgull Hornet airplane, N707BD, sustained substantial damage following an in-flight propeller separation and subsequent emergency landing near Camp Verde, Arizona. The airline transport pilot, the sole occupant of the airplane, sustained serious injuries. The airplane is registered to the pilot and was operated as a visual flight rules (VFR) personal flight under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed at the time of the accident. The flight originated from Camp Verde at 0730. No flight plan was filed for the local flight. The pilot reported that while in cruise flight, the engine began to sound like a "buzz saw" and he believed the 2-bladed wooden propeller had failed. He executed a forced landing into a nearby field. During the landing roll, the nose wheel separated and the pusher type engine separated from the mount assembly and fell into the cockpit area. The pilot reported that a postaccident examination of the airplane revealed that the exhaust bracket clamps separated (in flight) from the support structure, which resulted in a portion of the exhaust system contacting the wooden propeller. A witness stated that while in his home, he heard “banging and clanging and [an] engine running.” The witness exited his home and observed an airplane flying towards his house. The airplane flew over the house, banked towards the west and landed. Examination of the airplane by a Federal Aviation Administration inspector revealed that both blades of the wooden propeller were sheared approximately 6 inches outboard of the blade root. There was a minimal amount of wooden splinters located at the accident scene, all of which were in the fuselage below the engine. Seven of the eight engine mount bolts were sheared at the adapter plate mount and the eighth bolt was missing.