ERA25LA142 · Cessna TU206G

The pilot reported that he was flying to the surveying location about 1,800 ft mean sea level (msl) for about 10 minutes after departing when the engine “just stopped.” He stated that there were no indications of an engine problem until it suddenly lost total power. He switched the fuel tanks and verified the magneto switch position, but the engine did not regain power. He attempted a forced landing in a field but, as the airplane touched down, the left wing contacted trees and stopped the airplane abruptly. The left wing was substantially damaged, and fuel began to leak into the cabin. The pilot and pilot-rated passenger exited through the aft door and called the departure airport’s air traffic control tower for assistance. Postaccident examination and an engine test run revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Data recovered from the engine data monitoring device installed in the airplane showed that the engine consumed about 10 gallons per hour (gph) more fuel than indicated by the calculations in the Pilot’s Operating Handbook (POH) when the airplane was at a cruise altitude of 1,700 ft mean sea level (msl). The fuel flow increased above that previously established level just before the engine stopped producing power. With the data showing a high fuel flow spike just before the loss of engine power, and the pilot indicating that the mixture lever had been set to the full rich position since takeoff, the spike was likely the result of the higher-than-recommended mixture setting and inadvertent activation of the airplane’s auxiliary fuel pump, which enrichened the fuel-to-air mixture past the point of the engine’s combustion capability. This condition was the subject of a note in the airplane’s POH.

Verbatim NTSB analysis and probable cause from the NTSB dataset