NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The commercial pilot took off for a personal flight and flew uneventfully for about 44 minutes, including a touch-and-go landing at another airport about 10 minutes before the accident, after which the pilot made several turns in the area. According to the recovered flight data from the airplane’s avionics system, during the last minute of the recorded data, the airplane was in a gradual climb with a pitch-up attitude of about 7 degrees and a left bank of about 5 degrees; the airspeed was gradually decreasing. In the next 30 seconds, the airplane’s pitch increased to a maximum of 28 degrees nose up, and the airspeed decreased to a minimum of 38 knots indicated airspeed. The engine maintained about 2,200 rpm during this time. The airplane’s Pilot’s Operating Handbook (POH) states that the stall speed for the airplane is 41 knots indicated airspeed with the flaps up and power at idle. The data were consistent with a power-on stall. The POH states that for power-on stall recovery, the pilot is to simultaneously decrease power and lower the nose.
Following the stall, the airplane’s pitch then decreased to a maximum of 69 degrees nose down before it stabilized about 30 degrees nose down for the remainder of the recording with a descent rate of about 4,500 ft per minute. The airplane then banked from 76 degrees left to 75 degrees right in about 1 second; at this point, the engine power began to decrease. The bank stabilized about 10 degrees right for the remainder of the recording. Spins completed about every 2 seconds were recorded during the final 20 seconds. Further, during this final 20 seconds, the airplane’s engine rpm decreased from 2,100 to 1,800 rpm.
The POH lists recovery procedures to accomplish should an inadvertent spin occur. The first step is to immediately retard the throttle to the idle position. The next steps are to place the ailerons in the neutral position and then apply and hold full rudder opposite to the direction of rotation. The POH has a warning that recommends spin procedures be memorized to ensure prompt and proper recovery techniques are used in the event that an inadvertent spin is encountered. The recorded data revealed that, although the pilot pitched the nose down following the power-on stall, he did not simultaneously reduce the power. Further, the airplane’s engine throttle was not immediately retarded to the idle power position when the spin began, and the pilot did not apply the appropriate controls. Postaccident examination of the airplane revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.