The commercial pilot was taking off for a personal local flight in the Champion 7ECA.
He reported that, shortly after takeoff and as the plane reached about 700 feet above ground level, the engine began to gradually lose power.
He attempted to return to the departure airport, but was unable to maintain altitude.
He then chose to perform an off-airport landing near Sheridan, Arkansas, and the airplane hit trees.
Post-accident examination of the engine revealed no preimpact anomalies. A subsequent test run was performed, and no operational defects were noted.
The weather conditions were conducive for moderate icing at cruise power and serious icing at descent power, and the pilot’s description of a gradual and continual loss of engine power is consistent with the effects of carburetor icing. Therefore, it is likely that the engine lost power due to carburetor icing.
Probable cause: The partial loss of engine power due to carburetor icing.
NTSB Identification: CEN16LA025
This October 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
A gradual loss of power (and engine roughness) is the classic symptom of carb ice. If that happens, get the carb heat on immediately (aircraft control is first of course but in most cases the carb heat can immediately be applied).
Back in 1968, when I began training, my instructor taught that when doing the run up, don’t just pull the carb heat, watch the rpm drop, and then return it to off. He always preached to leave it out for 10-15 seconds to clear out any ice that may have formed while taxiing. If the rpm increased instead of decreased , then you had accumulated ice, and should be aware that on takeoff, you may have to use it if the engine begins to lose power.
Carb heat is not just for landing. It is for use anytime that conditions of temperature and humidity are conductive to carb ice formation.
A rich mixture such as you get with a full throttle carbs have a power enrichment function at take-off power[ to cool the engine in the climb]. But that excess fuel can cool warm air to below freezing in the carb venturi.
Fuel injection can ice but is much less prone because there is no fuel evaporation cooling in the venturi. But they still have alternate air [which is heated].