What happened
While performing maneuvers south of the airport to prepare for a VFR approach, the pilot of the aircraft entered a right spin. During the event, radar data indicated that the aircraft was flying at a speed significantly higher than its stall speed before it vanished from radar tracking.
Analysis of the radar records showed a rapid loss of both airspeed and altitude over two consecutive six-second intervals. In the first six-second period, the ground speed decreased by 31 knots, falling from 200 knots to 169 knots, while the altitude decreased by 440 feet, moving from 11,760 feet to 11,320 feet at a rate of 4,400 feet per minute. In the subsequent six seconds, the ground speed dropped by an additional 31 knots to 138 knots, and the altitude plummeted by 1,020 feet, reaching 10,300 feet at a descent rate of 10,200 feet per minute.
Findings
Technical data from the manufacturer suggests a potential mechanism for the loss of control. If the throttles are moved into the Beta range, there is a possibility that one propeller could enter the flat pitch range slightly before the other. Such an occurrence could cause the aircraft to undergo an immediate snap roll and transition into a spiral. At the time of the accident, the pilot had completed approximately 4 hours of dual instruction in the aircraft.