History of Flight
On June 7, 2016, at about 1020 central daylight time, an amateur-built Kitfox IV single-engine airplane, N921RP, impacted a lake near De Smet, South Dakota. The pilot and passenger had departed from Lake Preston Municipal Airport around 0929 to assist in searching for a boat that had sunk on June 3. While maneuvering at a low altitude, the airplane entered a right racetrack pattern about 150 feet above ground level, with banks of 45 to 60 degrees and an airspeed of approximately 50 mph. During a turn, the airplane "snapped over," and the pilot stated it had stalled. The airplane then spun about 1.5 to 2 rotations before impacting the lake and sinking. The passenger reported that the engine operated normally until the impact. The passenger was rescued by individuals involved in the boat recovery, but efforts to rescue the pilot were unsuccessful.
Personnel Information
The pilot held a private pilot certificate with an airplane single-engine land rating. The most recent third-class medical certificate was issued on January 26, 2015, with a corrective lenses limitation. A review of the pilot's logbook (noted as "Logbook Number 5") showed entries from February 14, 2015, to June 5, 2016, indicating 1,179.2 total flight hours, with 28.7 hours in the accident airplane.
Aircraft Information
The two-seat, high-wing, tailwheel-configured Kitfox IV (serial number 1589) was manufactured in 1991. It was powered by a Rotax 582 LC 65-horsepower engine and equipped with a composite three-blade ground-adjustable propeller. The pilot purchased the airplane on May 10, 2010. The most recent condition inspection was completed on July 11, 2015, at a total airframe and engine time of 432.6 hours. The hour meter at the accident site read 442.5 hours.
Meteorological Information
At 0956, the automated weather observing system at Brookings Regional Airport (BKX), approximately 30 miles east of the accident site, reported calm winds, clear skies, temperature 17°C, dew point 7°C, and an altimeter setting of 30.04 inches of mercury.
Wreckage and Impact Information
The airplane was recovered from the lake and examined. The fuselage was buckled near the aft cabin bulkhead, and the forward fuselage was crushed up and aft. The left wing exhibited compression bending aft near the wing root, and the forward wing attachment was fractured. The left flaperon remained attached, but its control fitting was fractured consistent with impact damage. The right wing sustained minor damage and remained attached. The empennage was intact with the rudder and elevator attached; minor damage to the bottom of the rudder was noted. The tailwheel remained attached, while both main landing gears had separated from the fuselage. Flight control continuity was established from the cockpit to the control surfaces. The seat restraints were found unbuckled, the flap handle was in the up position, the throttle was pulled out about 1.5 inches, and the fuel selector was on. The engine remained attached, and manual rotation revealed compression and mechanical continuity. Two of the three propeller blades were fractured aft near the blade root.
Medical and Pathological Information
An autopsy of the pilot determined the cause of death to be asphyxia due to drowning during the accident. Toxicology testing by the FAA Civil Aerospace Medical Institute was negative for all substances tested.
Tests and Research
An SD card from an iFly 700 Adventure Pilot GPS was recovered and submitted for data recovery. The card was undamaged, and data from 164 track logs spanning February 14, 2009, to June 7, 2016, were extracted. The accident flight recording started at 0929:12 and ended at 1019:51. The data included GPS altitude, ground speed, true course, and position. The flight departed Y34, turned southwest, and climbed to about 2,300 feet GPS altitude. Approaching Lake Thompson, it descended to between 2,000 and 2,100 feet msl (lake elevation 1,700 feet msl). The airplane began a north/south pattern with 3.5 to 4 nautical mile legs before circling a point on the western side of the lake starting at 1007. The last recorded data point was at 1019:51 at a GPS altitude of 1,955 feet and a ground speed of 34 knots. Due to data buffering, the recording may have ended before impact.