HISTORY OF FLIGHT On January 15, 2010, about 1450 central standard time, an experimental, amateur-built RV-4, N107SS, was substantially damaged when it impacted trees and terrain near Picayune, Mississippi. The certificated private pilot/owner and the passenger were fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which originated at Mint Julep Airpark (5MS5), Picayune, Mississippi, about 1445. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. During an interview with a Federal Aviation Administration (FAA) inspector, an acquaintance of the pilot stated that he and the pilot were performing maintenance on their respective airplanes at the pilot's home. The pilot was attempting to fix the accident airplane's autopilot, which was experiencing a "power flicker" in-flight that he was not able to duplicate on the ground. After replacing a ground wire, the pilot reassembled the airplane and prepared the airplane for a test flight. About 1445, the pilot and the passenger boarded the accident airplane, the engine started, and the airplane taxied out and departed to the north. The acquaintance described the takeoff as "normal," and that it was the last time he saw the accident airplane. A witness, who was standing about 1/4 mile northwest of the runway, saw the airplane shortly after it departed. He noticed that the airplane was low, and that it appeared that it was "about to do some tricks." The airplane rolled to the left and pitched down, then impacted the ground. PERSONNEL INFORMATION A review of FAA airman records revealed that the pilot held a private pilot certificate with a rating for airplane single-engine land. His most recent FAA third class medical certificate was issued in January 2009. The pilot accrued 1,859 hours of total flight experience; of which, 100 hours were in the same make and model as the accident airplane. He logged 30 hours of flight experience in the 90 days prior to the accident. AIRCRAFT INFORMATION According to FAA records, the airplane was issued an airworthiness certificate in 1989, and was registered to an individual in June 2006. It was equipped with a Lycoming O-320 series engine. It was a two-place, all-metal, low-wing, single-engine, cantilever monoplane with tailwheel type landing gear. Review of maintenance records conducted by an FAA inspector revealed that the airframe accrued 1,345 total hours of operation at the time of the accident. METEOROLOGICAL INFORMATION The weather reported at Stennis International Airport (HSA), Bay St. Louis, Mississippi, located 11 nautical miles south, at 1451, included scattered clouds at 3,500 feet, 10 statute miles visibility, winds from 030 degrees at 10 knots, temperature 15 degrees C dewpoint 08 degrees C, and an altimeter setting of 30.05 inches of mercury. WRECKAGE AND IMPACT INFORMATION A Federal Aviation Administration inspector responded to the accident scene, and examined the wreckage. According to the inspector, the trees in the immediate vicinity of the wreckage appeared largely undisturbed. The inspector noted that the branches all appeared to be broken vertically, and noted several vertical scratches on the tree trunks. All flight control surfaces were accounted for at the scene. The airplane came to rest in a slight nose down attitude, with the left wing displaced aft and the right wing displaced forward in relation to the fuselage. The front attachment point of the left wing and the rear attachment point of the right wing were broken. The trailing edge root area of the left wing, the leading edge outboard section of the left wing, and the leading edge root area of the right wing and the exhibited compression damage. The empennage of the airplane was twisted to the left and the left horizontal stabilizer was impact damaged. The leading edges of the elevators and rudder did not exhibit leading edge damage. The right side of the empennage displayed compression damage. Control cable continuity was traced from the tail and left aileron to the cockpit area. Both blades of the wooden propeller were broken about 4-inches outboard of the hub, with the remaining pieces of the blades scattered around the scene. A cursory examination of the engine was conducted, and no evidence of any mechanical failures or malfunctions was observed. There was no post-impact fire, and a strong odor of fuel was present. The National Transportation Safety Board retained and reviewed the airplane's electronic flight instrument system and found that it contained no data relevant to the accident. MEDICAL AND PATHOLOGICAL INFORMATION The Hancock County, Mississippi Coroner's Office performed an autopsy of the pilot. The autopsy report indicated that the cause of death was a result of "blunt frontal impact." The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing of the pilot. Fluid and tissue specimens tested negative for carbon monoxide, cyanide, and ethanol. TEST AND RESEARCH Weight and balance calculations were performed using weight and balance documents recovered at the site and the actual weights of the occupants. Calculations revealed the airplane weighed about 1,756 pounds at takeoff, with a center of gravity at 77.67 inches aft of datum. The manufacturer's center of gravity (CG) range at maximum gross weight was 68.7 to 77.4 inches aft of datum. The manufacturers recommended maximum gross weight was 1,500 pounds. ADDITIONAL INFORMATION FAA Advisory Circular 61-67C "As the CG is moved aft, the amount of elevator deflection needed to stall the airplane at a given load factor will be reduced. An increased AOA will be achieved with less elevator control force. This could make the entry into inadvertent stalls easier, and during the subsequent recovery, it would be easier to generate higher load factors due to the reduced elevator control forces....Although the distribution of weight has the most direct effect on stability, increased gross weight can also have an effect on an aircraft's flight characteristics, regardless of CG position. As the weight of an airplane is increased, the stall speed increases. The increased weight requires a higher AOA to produce additional lift to support the weight."