NTSB

Probable cause: The failure of the pilots to apply prompt and/or correct flight control inputs to adequately recover from the intentional aerodynamic spin.

Probable cause: The pilot’s failure to properly deice the airplane before takeoff, which resulted in an aerodynamic stall during the initial climb.

Probable cause: Maintenance personnel’s incorrect installation of the No. 3 cylinder’s hydraulic valve tappet plunger, which resulted in a failure of the No. 3 cylinder’s intake valve and the subsequent partial loss of engine power. 

Probable cause: The pilot’s failure to maintain an appropriate glidepath to the runway and to use the vertical guidance system.

Probable cause: The failure of maintenance personnel to ensure that the throttle and fuel metering unit AN “B” nut was secured, which resulted in a total loss of engine power in flight and a subsequent collision with trees while attempting

Probable cause: The pilot’s failure to maintain directional control while landing in flat light conditions on a hard-packed snow-covered landing area.

Probable cause: The student pilot’s inadvertent use of the control yoke to correct for a drift and his subsequent failure to maintain directional control during takeoff.

Probable cause: The pilot’s loss of control while maneuvering for reasons that could not be determined based on the available information.

Probable cause: The pilot’s incapacitation from carbon monoxide poisoning in flight due to cracks in the exhaust muffler, which resulted in the airplane’s continued flight until it ran out of fuel and its subsequent collision with terrain.