Cessna 182A N9909B accident near Selma, California

Probable cause

The total loss of engine power due to carburetor icing, which resulted from the flight instructor's failure to use carburetor heat during the descent.

NTSB analysis

Following an uneventful flight, the flight instructor and student pilot began a descent toward an airport where they intended to refuel the airplane. The flight instructor reported that, during the descent, the engine lost power. After notifying air traffic control, they received vectors to the nearest airport. Despite multiple attempts, the flight instructor was unable to restart the engine. He realized that the airplane would not be able to reach the airport, so he initiated a forced landing to an open sand- and dirt-covered field. During the landing roll, the airplane nosed over. The flight instructor reported that he did not use carburetor heat during the descent.

During examination of the airplane, the fuel strainer valve was stuck in the open position and the valve and the mixture metering sleeve were contaminated with sandlike debris, which likely entered the system during the accident sequence. The debris was removed. The fuel strainer valve then closed, indicating the impact sequence caused it to open. The carburetor was reassembled and reinstalled on the engine, and the engine started and ran continuously at various power settings until it was shut off using the mixture control.

Recovery personnel noted that each wing fuel tank contained less than 2 quarts of fuel; the wings were not breached. Fuel burn calculations revealed that the airplane would have used 43.5 gallons of fuel after the airplane was topped off with fuel about 1 hour before the flight and should have had about 21.5 gallons of fuel remaining (the two tanks had a total capacity of 65 gallons), 18.5 gallons of which would have been usable. It could not be determined why only about 2 quarts of fuel remained in each wing tank.

Weather conditions in the area at the time of the accident were conducive to the formation of carburetor icing at glide and cruise power. It is likely that the flight instructor's failure to use carburetor heat during the descent resulted in the accumulation of carburetor icing and subsequent total loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR16LA094 for the full record.