Cessna 150J N60860 accident near Buffalo, Iowa

Probable cause

A loss of engine power due to fuel exhaustion as a result of the pilot’s inadequate preflight planning. Contributing to the accident were the unreliable fuel quantity gauges and the improperly adjusted mixture control, which increased the fuel consumption above that anticipated by the owner’s manual.

NTSB analysis

The pilot had completed 3 flight legs immediately before the accident flight without incident. The accident flight proceeded normally until it neared the destination airport. The pilot reported a rapid drop in engine speed as if the throttle control had been abruptly moved to idle. The engine seemed to completely lose power for about 30 to 45 seconds. It then regained a “strong burst” of power. However, about 5 to 10 seconds later, the engine lost power again. His efforts to restore engine power were not successful. He attempted to execute a forced landing to a road; however, a wind gust caused the airplane to impact a light pole before it came to rest on railroad tracks. The nose landing gear collapsed and the airplane was oriented in a nose-down position, with damage to the fuselage, engine mount, and both wings.

Postaccident examination did not identify any engine anomalies consistent with an inability to produce rated power. Both main fuel tanks appeared to be intact; however, both appeared to contain only a minimal amount of fuel. The gascolator bowl contained fuel, which was consistent with the airplane resting in a nose-low attitude after the accident.

The airplane was fully fueled (22.5 gallons useable) before departing initially and was fueled with 20 additional gallons during the previous flights. According to the airplane owner’s manual, the expected fuel consumption varied from about 5.5 gallons per hour (gph) to about 7.0 gph. The pilot reported the engine was leaned as appropriate for all stages of flight.

The pilot also noted that the engine took about 2 minutes to shut down after the mixture control was moved to the idle/cutoff position at 2 of the intermediate stops. This suggests an improperly adjusted mixture control that would have resulted in a slightly rich mixture and higher than anticipated fuel consumption. The pilot also reported the fuel gauges were not reliable as they did not indicate the correct amount of fuel that he visually verified was in the tanks.

The total flight time over the 3 preceding flights and the accident flight was about 6 hours. Based on the lack of fuel onboard the airplane, a total fuel consumption of 42.5 gallons would equate to about 7 gallons per hour, within the range of the published fuel consumption for the airplane. Also, the fuel consumption was likely higher than anticipated due to the improperly adjusted mixture.

Although weather conditions at the time of the accident were conducive to carburetor icing, the loss of engine power as described by the pilot was not consistent with a carburetor icing scenario.

Based on the available information, the engine lost power due to fuel exhaustion. It is likely that a slightly rich mixture increased the fuel consumption from that anticipated by the owner’s manual.

Text from the NTSB. Open the NTSB docket for CEN23LA163 for the full record.