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Accident caused by failure to use carburetor heater — General Aviation News

Accident caused by failure to use carburetor heater — General Aviation News
Accident caused by failure to use carburetor heater — General Aviation News

The pilot reported that during cruise at an altitude of approximately 4,000 feet above sea level, he applied the throttle to initiate a climb, but the engine lost power. To restore power, he continued to operate the throttle and propeller levers and moved the fuel selector to the left tank, but to no avail.

He made an emergency landing in a small canyon near Soldotna, Alaska, resulting in significant damage to the wings and fuselage.

The pilot suffered serious injuries in the crash, one passenger remained uninjured.

A Global Data Assimilation System (GDAS) model sounding was constructed for the time and location of the accident, with the modeled surface elevation being approximately 2,415 feet above sea level. When the data were interpolated to an elevation of 4,000 feet above sea level, the data yielded a temperature of approximately 4.9 °C (40.8 °F) and a dew point of approximately 1.6 °C (34.9 °F), with a relative humidity of approximately 79%.

Based on the carburetor icing probability diagram, these conditions would result in “severe icing – cruise performance.”

When asked whether he had switched on the carburetor heater after the loss of power, the pilot replied in the negative, as there was no moisture visible in the area and he considered carburetor ice to be unlikely.

A Lycoming maintenance instruction states, in part: “Flight operations – During normal flight, leave the carburetor air heater in the cool position. On humid, cloudy, foggy, or hazy days, watch for loss of power regardless of outside temperature. This will be indicated by an unexplained loss of manifold pressure or RPM, or both, depending on whether the airplane is equipped with a constant speed propeller or a fixed pitch propeller. If this occurs, turn the carburetor air heater on full and open the throttle to limit manifold pressure and RPM.”

Probable cause: A complete loss of engine power due to carburetor icing caused by the pilot’s failure to utilize carburetor heat while operating under conditions favorable to the formation of carburetor ice.

NTSB Identification: 105645

To download the final report, click here. This will trigger a PDF download to your device.

This July 2022 accident report is provided by the National Transportation Safety Board. It was published as an educational tool to help pilots learn from the mishaps of others.