History of Flight
On September 2, 2016, at about 1000 central daylight time, an experimental, amateur-built RV-6 airplane, registration N676DT, impacted a cornfield following a loss of control near Viborg, South Dakota. The commercial pilot and the passenger were fatally injured, and the airplane was destroyed. The airplane was registered to and operated by the pilot under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan had been filed. The local flight departed from Marv Skie-Lincoln County Airport (Y14), Tea, South Dakota, about 0900.
Family members reported that the passenger was the pilot's 14-year-old granddaughter, who aspired to become a pilot, and that it was common for them to take local flights on weekends. They added that the purpose of the flight was personal and not instructional.
A witness reported hearing an engine "sputtering," followed by a loud "thud," and then observed a fireball. The witness did not see the airplane in flight.
Aircraft Information
The airplane was built from a kit by a previous owner and configured for two occupants with side-by-side seating. It received a special airworthiness certificate with an experimental designation on September 11, 1996. The investigation was unable to determine when the airplane had been fueled last.
Meteorological Information
There were no active AIRMETs or SIGMETs near the accident location, and no PIREPS applicable to the accident area.
Wreckage and Impact Information
The accident site was located in a mature cornfield about 10 nautical miles west of Viborg and 27 nautical miles southwest of Y14. The airplane came to rest on top of corn stalks, some of which remained unbroken near the empennage. The wreckage exhibited no lateral or forward displacement. No airplane debris or noticeable crop damage was found outside the wreckage area. According to first responders, the passenger was seated in the left seat with her 4-point seatbelt fastened, and the pilot was seated in the right seat with his 4-point seatbelt fastened.
The engine cowling, cockpit, fuselage, and forward portion of the empennage were consumed by a postimpact fire. The wing roots and bottom side of the fuselage were thermally damaged. The wing tank fuel caps were found in place and secure.
The left wing tip fairing separated and was found near the forward left side of the wreckage. The left wing exhibited rearward and upward impact crushing signatures, and impact marks were found under the left wing tip. The left flap was partially underneath the left wing and remained attached at connection points. The left aileron remained partially attached; the inboard connection remained attached while the outboard connection was impact separated. The left fuel tank was breached.
The right wing sustained leading edge damage and rearward crushing near the inboard section. The right flap was retracted and mostly undamaged. The right aileron was found in a neutral position, remained attached, and was mostly undamaged.
The aileron control tubes remained attached to the aileron surfaces and were continuous inboard to the fuselage where they were consumed by fire. The elevator control tube remained attached to the elevator surface and extended about 4 ft into the rear fuselage where it was thermally damaged and partially consumed. The forward portion remained attached at the control stick. The elevator trim tab was slightly down from neutral. Rudder control cables remained attached to each side of the rudder and were continuous to the forward ball swage in the cockpit area; the right ball swage was covered with melted aluminum. Rudder pedals were found in the forward cockpit near the firewall and sustained thermal and impact damage.
The throttle and mixture control knobs were near full forward. Cockpit instrumentation was mostly consumed by fire. The ignition was positioned to "BOTH." The fuel selector was set to the right fuel tank position.
The two-bladed metal propeller remained attached to the crankshaft flange, embedded in the soil, and positioned horizontally. The blades were slightly bent aft with no leading edge damage.
The engine remained attached to its mounts and sustained thermal damage primarily near the rear, encompassing accessories. The top spark plug electrodes, all automotive style, were free of damage and exhibited normal coloration. The empennage and exhaust manifold had no visible oil residue. Engine mechanical continuity was established from the vacuum pump drive to the propeller flange. When the crankshaft was rotated via the accessory drive gear, thumb compression and suction were obtained at each cylinder. Valve rockers were undamaged and moved normally. The magneto drive gear and fuel pump plunger actuated when the accessory drive gear was rotated. The engine-driven fuel pump was thermally damaged. The carburetor remained secure with mixture and throttle controls connected; throttle was near full open, mixture near full rich. The carburetor fuel inlet screen was free of contaminants, and the air inlet was unobstructed. The float bowl was free of contamination; plastic floats were thermally damaged. Left and right electronic ignition components were thermally damaged. The ignition harness was mostly consumed but appeared connected at each spark plug. The vacuum pump remained secure; its plastic coupler was thermally damaged. The engine oil suction screen was free of contaminants.
Postaccident examination of the engine and airframe did not reveal any mechanical malfunctions or anomalies that would have precluded normal operation. The postimpact fire prevented a complete examination.
Additional Information
A review of FAA radar data revealed no radar returns correlating to the flight, and no air traffic control communications were found. An undamaged Appareo Stratus PRX V2 was found near the wreckage; the NTSB Recorders Laboratory downloaded it but found no data from the accident flight. The pilot's iPad was found by the family; the ForeFlight application contained 37 previous flight track logs from November 29, 2014, to July 26, 2016.
Medical and Pathological Information
The Sanford Health Pathology Clinic, Sioux Falls, South Dakota, completed an autopsy on the pilot; the cause of death was multiple blunt force injuries. The FAA's Bioaeronautical Sciences Research Laboratory conducted toxicology testing, which revealed verapamil and norverapamil in the blood and liver. Verapamil is a prescription drug used for hypertension, angina, and arrhythmias; norverapamil is a metabolite.
An autopsy on the passenger was also completed; the cause of death was blunt force injury. Toxicology testing was negative for carbon monoxide in the blood.