N4087VCessna 170 · 1948

The pilot reported that while doing pattern work, during his third approach, he turned base 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. Unable to reach the runway, the pilot selected a field to complete the forced landing, and during the landing roll, the airplane collided with a fence.

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 3,000ft.

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.

According to the FAA Carburetor Icing Chart, a moderate chance of carburetor ice accumulation existed at cruise power. Light icing accumulation over a prolonged period may become serious, according to FAA Winter Flying Tips.

According to the manufacturer's pilot operating handbook, the fuel pump is to be "On" during takeoff and landings.

Additionally, the pilot reported that the accident could have been prevented by turning on the fuel pump during takeoffs and landings, and by turning on the carburetor heat on the downwind before landing.