De Smet, SD, USA
N921RP
PRUSS RICHARD S KITFOX IV
During a personal local flight, the private pilot and passenger, who held a student pilot certificate, were searching a lake for a submerged boat. The passenger stated that while maneuvering at a low altitude, the pilot banked the airplane about 45 to 60 degrees at an airspeed of about 50 miles per hour. During the turn, the airplane stalled, entered a spin, and impacted the water. A postaccident examination of the airframe and engine did not reveal any evidence of a mechanical malfunction or failure that would have precluded normal operation. Data from a GPS unit recovered from the airplane indicated that the airplane was about 250 ft above ground level at a ground speed of about 34 knots when it stalled. Based on the passenger's statements and the GPS data, it is likely that the pilot failed to maintain adequate airspeed and exceeded the airplane's critical angle-of-attack while maneuvering, which resulted in an aerodynamic stall/spin from which he had insufficient altitude to recover.
HISTORY OF FLIGHT On June 7, 2016, about 1020 central daylight time, an amateur-built Kitfox IV single-engine airplane, N921RP, impacted a lake following a loss of control while maneuvering at a low altitude near De Smet, South Dakota. The private pilot sustained fatal injuries, the passenger sustained serious injuries, and the airplane sustained substantial damage. The airplane was registered to and operated by the pilot as a 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was not filed. The local flight departed from Lake Preston Municipal Airport (Y34), Lake Preston, South Dakota, about 0929. According to the passenger, who held a student pilot certificate and was interviewed by a Federal Aviation Administration (FAA) inspector, the pilot picked him up at Y34 to assist in a search for a boat that sank in Lake Thompson on June 3, 2016. The pilot and passenger spotted the boat and then flew a right "racetrack" pattern about 150 ft above ground level. While maneuvering, the airplane was banked about 45 to 60 degrees at an airspeed of about 50 miles per hour. During one of the turns, the airplane "snapped over" and the pilot told the passenger that the airplane stalled. The airplane spun about 1.5 to 2 rotations, impacted the lake, and sank. The passenger stated the engine operated normally until the impact with the water. According to local authorities, the passenger was rescued by persons assisting in the boat recovery. Efforts to rescue the pilot were unsuccessful. PERSONNEL INFORMATION The pilot held a private pilot certificate with an airplane single-engine land rating. The pilot's most recent third class medical certificate was issued on January 26, 2015, with a limitation for corrective lenses. A review of the pilot's logbook, noted as "Logbook Number 5", revealed that the first logbook entry was dated February 14, 2015, and the last logbook entry was dated June 5, 2016. According to the information contained in the logbook, at the time of the last logbook entry, the pilot had accumulated 1,179.2 total flight hours, of which 28.7 hours were in the accident airplane. AIRCRAFT INFORMATION The two-seat, high-wing, tail-wheel configured airplane, serial number 1589, was manufactured in 1991. The airplane was powered by a Rotax 582 LC 65-horsepower engine, and was equipped with a composite 3-blade ground-adjustable propeller. The airplane was purchased by the pilot 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 reading observed at the accident site was 442.5 hours. METEOROLOGICAL INFORMATION At 0956, the automated weather observing system at the Brookings Regional Airport (BKX), Brookings, South Dakota, located about 30 miles east of the accident site, recorded the following weather conditions: wind calm, sky clear, temperature 17 degrees Celsius, dew point 7 degrees Celsius, and an altimeter setting of 30.04 inches of mercury. WRECKAGE AND IMPACT INFORMATION The airplane was recovered from the lake and examined at a facility near Lake Thompson. Examination of the airplane showed that the fuselage was buckled near the aft cabin bulkhead. The forward fuselage was crushed up and aft. The left wing displayed compression bending aft near the wing root, and the forward wing attachment was fractured. The left flaperon remained attached and its control fitting was fractured. The fracture was consistent with impact damage. The right wing remained attached to the fuselage and sustained minor damage. The right flaperon remained attached. The empennage was intact with the rudder and elevator attached and minor damage was noted to the bottom of the rudder. The tailwheel remained attached and both main landing gears were separated from the fuselage. Flight control continuity was established from the cockpit controls to the respective flight control surfaces. The seat restraints were attached to the fuselage and were found unbuckled. The flap handle was observed in the up or retracted position. The throttle was pulled out about 1.5 inches, and the fuel selector was on. The engine remained attached to the engine mount and fuselage. The propeller remained attached to the engine, and the propeller was manually rotated. Manual rotation of the propeller revealed compression and mechanical continuity throughout the engine. Two propeller blades were fractured aft near the blade root. MEDICAL AND PATHOLOGICAL INFORMATION The autopsy of the pilot was performed at the Sanford Health Pathology Clinic, Sioux Falls, South Dakota. The cause of death was asphyxia due to drowning during an airplane accident. Toxicology testing by the FAA Civil Aerospace Medical Institute was negative for all substances tested. TEST AND RESEARCH The SD card from an iFly 700 Adventure Pilot GPS that was recovered from the airplane was submitted to the NTSB Vehicle Recorder Division for data recovery. The card was undamaged and data was recovered normally. The data extracted included 164 track logs from February 14, 2009, through June 7, 2016. The accident flight was recorded starting at 0929:12 and ending at 1019:51. The GPS data parameters recorded were the following: date, time, latitude, longitude, GPS speed, true course, and GPS altitude. According to the data, the flight departed Y34 at 0929, turned southwest, and climbed to about 2,300 feet GPS altitude. As the airplane approached Lake Thompson, it descended to between 2,000 and 2,100 feet mean sea level (msl); Lake Thompson is at 1,700 feet msl. The airplane began flying a north/south pattern with 3.5 to 4 nautical mile legs. At 1007, the airplane began circling a point towards the western side of the lake. 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 on the GPS unit, the data recording may have ended before the airplane impacted the lake.
The pilot's failure to maintain adequate airspeed and his exceedance of the airplane's critical angle-of-attack during a steep turn at a low altitude, which resulted in an aerodynamic stall/spin at too low of an altitude to recover.
Source: NTSB Aviation Accident Database
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