On September 2, 2005, about 0915 Pacific daylight time, an unregistered Kirner homebuilt Fisher FP404, owned and operated by the pilot as a 14 CFR Part 91 personal flight, experienced an in-flight separation of the right wing while maneuvering over open terrain located 10 nautical miles south of Prineville, Oregon. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The aircraft was destroyed and the private pilot, the sole occupant, was fatally injured. The aircraft departed from Prineville about 0845. A witness in the area reported that he had been watching the aircraft perform "hard banks followed by 2-3 spins." The witness stated that the aircraft would recover and gain altitude to repeat the maneuver. The aircraft accomplished these maneuvers three times. The witness then observed the aircraft for about 2-3 seconds fly straight-and-level. The engine sound accelerated before the aircraft then pitched forward into a steep dive which lasted about 2-3 seconds before the witness observed what he believed was the right wing (upper or both) separate from the fuselage. The aircraft continued in a vertical dive while spinning to the ground. On site documentation of the wreckage by a Federal Aviation Administration Inspector from the Hillsboro, Oregon, Flight Standards District Office reported that the right wing section was found about 200 yards south of the main wreckage. Additional debris fragments were found laying approximately 200 yards further south beyond the wing section. The inspector stated that the lower right wing bolt which attaches the wing to the fuselage was in place, however, the wood material around the bolt pass through failed. Documents provided to the FAA Inspector by a friend of the pilot indicated that the pilot had owned and operated the aircraft for about two years. During this time, the aircraft had been weighed indicating an empty weight of 339 pounds. The pilot did not register the aircraft nor was there an airworthiness certificate. The pilot, who is not a certificated airframe or powerplant mechanic, was also accomplishing his own maintenance on the aircraft.