Beech 58 N142DR accident near Galt, California

Probable cause

The certified flight instructor's failure to maintain control of the airplane and inadequate supervision of the flight, which resulted in an aerodynamic stall/spin from which he could not recover.

NTSB analysis

The pilot under instruction and the certified flight instructor (CFI) departed in the multi-engine airplane to conduct training. Radar data indicated that they proceeded to multiple airports and performed traffic pattern work including takeoff and landings. After departing the last airport, they performed two 360° turns and one power off stall task. The airplane again slowed and recorded engine data indicated that, while the critical engine’s speed was reduced, the other engine’s speed was increased, consistent with performing a Vmc demonstration. During a Vmc demonstration, power is reduced on the critical engine (left) and the airplane is recovered before loss of directional control or stall. As the airspeed decreased, the airplane entered a rapid descent with a continuous left-hand turn that was observed by witnesses as it was spinning, not nose down, with a flat attitude until water impact.

Impact signatures were consistent with a slightly nose-low, near-flat attitude. Postaccident examination of the engines and airframe did not reveal evidence of any mechanical malfunctions or anomalies that would have precluded normal operation of the airplane. Positive identification of who was on the controls during the Vmc demonstration could not be determined given the available evidence.

Text from the NTSB. Open the NTSB docket for WPR22FA332 for the full record.