On August 5, 2005, about 1122 Pacific daylight time, an experimental Harmon/Lance RV-4, N683RV, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, collided with trees and the terrain while maneuvering for landing at the Cavanaugh Bay Airport, Coolin, Idaho. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged during the impact and post crash fire. The private pilot and his passenger were fatally injured. The flight departed from Scappoose, Oregon, about two and a half hours prior to the accident. Witnesses in the area reported seeing the aircraft first fly over the bay, "...very low over the water, at times only 50 to 100 feet above the lake." This witness stated that the plane "buzzed" over the houses on the east side of Coolin Bay. The aircraft made two passes over the houses, then flew north towards Rocky Point and Cavanaugh Bay at a "very low altitude." Another witness reported that when he first saw the aircraft he thought that it had just taken off as the aircraft was "just above the trees when it suddenly veered hard to the right and disappeared into the trees." Smoke was seen almost immediately after he lost sight of the aircraft. The accident site was located among and in an area of dense trees and underbrush at global positioning system (GPS) coordinates 48 degrees 30.767 north latitude, 116 degrees 49.230 west longitude. The site elevation is approximately 2,457 feet. On site documentation of the area by an officer from the Idaho State Police reported that the aircraft was facing southeast and resting on its top. The right wing remained in place and positioned to the north. The leading edge of the wing displayed impact signatures consistent with impact to trees. The left wing was folded back against the fuselage and positioned to the rear. The tail section was inverted and the control surfaces were attached. The fuselage, cabin and a portion of the right wing was extensively burned. Trees located about 75 to 85 feet to the south of the wreckage had their tops broken off. The largest diameter and tallest tree was broken off at 65 feet above ground level (agl). About 15 to 20 feet of the tip of the tree was lodged in other trees. A second smaller diameter tree was sheared off at 60 feet agl. Several other smaller trees located between the initial impact and the main wreckage had their tops broken off. A Federal Aviation Administration Inspector from the Spokane, Washington, Flight Standards District Office, responded to and was at the accident site later that day. The inspector confirmed that all flight controls were present and partial flight control continuity was established. Extensive fire damage destroyed a majority of the flight control system. Toxicological samples were sent to the Federal Aviation Administration Civil Aeromedical Institute, Oklahoma city, Oklahoma, for analysis. The report indicated negative results for Carbon Monoxide, Cyanide, Volatiles and Drugs. The turf airstrip is 3,100 feet long and 120 feet wide. The airstrip terrain rises to the north with trees on both ends. The elevation is 2,484 feet. Witnesses reported the temperature at the time as about 100 degrees.