HISTORY OF FLIGHTOn September 26, 2018, about 1442 central daylight time, an amateur-built Vans RV-4 airplane, N534MM, was substantially damaged when it was involved in an accident near Austin, Arkansas. The private pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. Radar data showed that the airplane departed North Little Rock Municipal Airport (ORK), North Little Rock, Arkansas, about 1424 and flew at an altitude between 2,600 ft and 2,700 ft mean sea level (msl) and a ground speed of between 110 and 120 knots until just west of the pilot's home (see figure 1). The airplane started to descend about 1439 and the ground speed increased to about 145 knots. The last radar location was recorded at 1440:41 about over the pilot's home and the accident site was located in an open field a few hundred feet east of the pilot's home. Figure 1 - Radar data of accident flight In a postaccident interview, the pilot's wife stated that, before the pilot left the house for work, he said the weather was "not good" for flying and he did not plan to fly the airplane that day. Later, he called her from the airport and told her he was going to fly. She asked him if he was "sure about flying due to the weather," and he said the winds had decreased and it looked good for the flight. Then he told her when to stand outside their house to see him fly by. As the airplane flew overhead, the pilot's wife reported that she saw the right wing "tip up," the airplane climbed briefly, and then, "all of sudden," the airplane went upside down and dove down. She added that the airplane was flying so low and so fast that she knew he was not going to be able to recover. PERSONNEL INFORMATIONThe pilot actively flew Lockheed C-130 military transport airplanes, with the United States Air National Guard (US ANG). According to US ANG records, the pilot had logged a total of 5,613 hours of total time in the C-130. The pilot had received a tailwheel endorsement on September 21, 2018. According to the pilot's wife, the accident flight was the pilot's first flight in the airplane without a flight instructor. According to the pilot's flight instructor, most of the pilot's training in the airplane consisted of takeoffs and landings and minimal time was spent training maneuvers and performance characteristics. The pilot's Federal Aviation Administration (FAA) first-class medical certificate was issued on March 6, 2006, with the limitation that he must wear corrective lenses, and it expired on March 31, 2008. The pilot's military medical clearance was active. According to 14 CFR 61.23(b)(9), "Operations not requiring a medical certificate," pilots that have a current military medical clearance with the US armed forces are not required to hold a current medical certificate for domestic flights that require a third-class medical clearance. AIRCRAFT INFORMATIONThe instrument panel was destroyed by the postimpact fire; as a result, investigators were unable to determine the airplane's total time. METEOROLOGICAL INFORMATIONThe upper air sounding chart created for the accident site at 1500 indicated a surface wind from about 30° at 10 knots with the wind remaining northeasterly through 4,000 ft. The wind increased in speed to 15 knots by about 800 ft msl and to 20 knots by about 1,700 ft. Wind decreased to 10 knots at 4,000 ft msl, and about 5,000 ft msl the wind direction shifted to about 10º. The chart indicated below about 3,000 ft msl the atmosphere was unstable or conditionally unstable. AIRPORT INFORMATIONThe instrument panel was destroyed by the postimpact fire; as a result, investigators were unable to determine the airplane's total time. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted an open field, vegetated in grass, in a wings-level, nose-low attitude, between 35° and 40° nose down. The main wreckage came to rest about 185 ft south/southeast of the initial impact point oriented on a heading of 323°, on the edge of Rick Lake (see figure 2). Figure 2: Aerial photograph depicting initial impact point and location of main wreckage During the on-scene investigation, investigators located fiberglass and metal fragments, the left aileron, and both propeller blades in the debris field between the initial impact point and the main wreckage. The grass between the initial impact point and the main wreckage was discolored, which was consistent with fuel blighting. The main wreckage included the engine, fuselage, empennage, and both wings. A postimpact fire damaged the fuselage, the inboard portion of both wings, and the skin of the empennage. The main landing gear separated partially from the airplane but remained with the wreckage. The first ground scar was several inches deep, about 6 inches wide, and extended 5 ft to a larger ground scar. The larger ground scar consisted of three distinct sections; a center section, a left section, and a right section. The left section extended about 7 ft to the east and was about 1 ft 6 inches wide at its widest point. The right section extended about 7 ft to the west and was about 2 inches deep and 6 inches wide at its widest point. The center section extended south towards the main wreckage and was 9 ft long, several inches deep, and full of water. A dark substance consistent with oil pooled at the top of the water. Dirt was displaced out of the larger scar towards the main wreckage to the south. One propeller blade was on the right side of the debris field and was bowed aft and twisted. The second blade was 38 ft from the end of the main scar with the tip buried in the ground. The second blade also exhibited leading-edge scoring at the tip and was otherwise unremarkable. One half of the propeller hub was 70 ft from the second blade while the other half was buried about 1 ft 6 inches deep in the large ground scar. A line of trees and bushes between the initial impact point and main wreckage exhibited torn and separated bark. Witness marks on the trees and vegetation and discoloring of the leaves were also consistent with fuel blighting. A postaccident examination of the airframe and engine conducted by the National Transportation Safety Board and parties to the investigation revealed no preimpact anomalies that would have precluded normal operation. MEDICAL AND PATHOLOGICAL INFORMATIONThe Arkansas State Crime Laboratory, Medical Examiner Division, Little Rock, Arkansas, performed an autopsy of the pilot. The autopsy indicated that the cause of death was multiple injuries. Toxicological testing of the pilot's specimens performed by the FAA Forensic Sciences Laboratory was negative for carbon monoxide, ethanol, and drugs.