Accident Overview
The pilot-under-instruction (PUI), who held an expired medical certificate, and the pilot-in-command (PIC), an ATP-rated pilot with 1,240 hours in the Cessna 340, departed for the PUI's third training flight in the aircraft. The previous training flight, conducted one week earlier, had included single-engine operations.
Witness Observations
Multiple witnesses near the Richland airport observed the aircraft in flight. Several reported that the left propeller was turning slowly. All witnesses stated that the aircraft descended rapidly in a nose-down attitude, and several described the descent as a spin. The aircraft subsequently struck the ground in a nearly vertical, nose-low attitude and was destroyed by the ensuing fire.
Postcrash Examination
Examination of the wreckage revealed that the left propeller was in the feathered position, while the right propeller blades exhibited power signatures. Disassembly of both engines found no pre-impact mechanical malfunctions. The landing gear and flaps were retracted, and the rudder trim tab was set at approximately 5 degrees of left tab trim.
According to the Cessna 340 information manual, the single-engine minimum control speed (Vmc) is 82 knots indicated airspeed (KIAS). The manual also specifies that a more appropriate airspeed for one-engine-inoperative training maneuvers is 91 KIAS.
Probable Cause
The official probable cause of the accident was the pilot-in-command's failure to maintain airspeed above the single-engine minimum control speed (Vmc), leading to a stall/spin condition. Contributing factors included the PIC's decision to shut down the left engine, allowing the airspeed to drop below the manufacturer's recommended intentional one-engine-inoperative airspeed, and the aircraft's low altitude at the spin entry, which prevented recovery.