Cessna 170 N4087V accident near Selah, Washington

Probable cause

The pilot's failure to use carburetor heat while operating in conditions conducive to carburetor icing, which resulted in a partial loss of engine power and a subsequent forced landing and impact with a fence.

NTSB analysis

The pilot reported that, while doing pattern work and during his third approach, he turned to the base leg of the traffic pattern, and the engine lost power. He turned the fuel selector to "both," but he was unable to restart the engine. The airplane was equipped with an auxiliary fuel pump, which he did not turn on. Realizing the airplane would not reach the runway, the pilot chose to conduct a forced landing to a field, and during the landing roll, the airplane collided with a fence.

The airplane sustained substantial damage to the horizontal stabilizer.

The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.

After the collision, the pilot visually checked both fuel tanks, and each tank contained "ample fuel." He believed that the engine lost power due to carburetor ice because he did not apply carburetor heat during the approach.

The pilot reported that, about the time of the accident, the temperature was 38°F and the dew point was 30°F. Additionally, he recalled that the cloud condition was broken at 3,000 ft. The atmospheric conditions were conducive for moderate carburetor icing at cruise power.

The pilot reported that the accident could have been prevented if he turned on the fuel pump during the takeoffs and landings and if he had turned on the carburetor heat on the downwind before landing.

Text from the NTSB. Open the NTSB docket for GAA19CA126 for the full record.