Accident Overview
On January 18, 2019, at approximately 1530 central standard time, a Piper PA-24 aircraft, registration N6497P, was involved in an accident near Beechwood, Wisconsin. The private pilot, the sole occupant, sustained minor injuries. The airplane was substantially damaged. The flight was conducted under Title 14 Federal Code of Regulations Part 91 as a personal flight.
Sequence of Events
After 25 minutes of uneventful cross-country flight, the pilot observed that the carburetor temperature gauge was in the “yellow” range. The gauge then moved into the “red” range, which typically indicates freezing conditions. The engine began to lose power. In response, the pilot pulled the carburetor heat knob to the full “ON” position, set the fuel mixture to full rich, and activated the electric fuel pump. Despite these actions, engine power did not improve.
The pilot then checked the magnetos and switched the fuel tank selection from left to right. When the pilot pushed the carburetor heat knob back to the “OFF” position, the engine ran more smoothly but power did not increase. He pulled the carburetor heat knob back to “ON,” but the engine continued to run poorly.
By this time, the airplane had descended to 2,000 feet. The pilot trimmed the airplane for 100 mph. Although the engine remained running, no power increase was observed. The pilot again engaged carburetor heat, with no effect. The descent rate was approximately 700 feet per minute as the airplane passed through 1,200 feet.
Emergency Landing
The pilot made a distress call and announced an emergency landing. He configured the airplane for a gear-up landing in a field. During the landing, the airplane sustained substantial damage to the fuselage.
Post-Accident Examination
According to a carburetor icing probability chart, given a temperature of -7°C and a dew point of -14°C, it could not be determined whether the airplane’s carburetor could have been susceptible to icing because the dew point depression was outside the chart’s matrix.
Damage to the carburetor assembly prevented a determination of proper rigging. However, examination of the engine and fuel system revealed no anomalies. The carburetor heat control was found in the forward, “OFF” position.