Cessna 150M N66748 accident near Wadsworth, Ohio

Probable cause

A partial loss of engine power due to carburetor icing and the pilot’s failure to apply carburetor heat when the power loss occurred.

NTSB analysis

The pilot reported that, shortly after takeoff, she noticed that the airplane was not climbing normally and heard the stall warning horn. The pilot then noticed the engine speed was rapidly decreasing from 2,500 to 1,500 rpm. The pilot established the airplane’s best glide speed and prepared for a forced landing to a corn field. She did not apply carburetor heat. After touchdown, the airplane nosed over, resulting in substantial damage to the fuselage, vertical stabilizer, and rudder.

A postaccident examination of the engine revealed low compression on the No.1 cylinder, but, after staking the valves, compression increased with no leaking past the valves. Also, the airplane’s most recent annual inspection was completed 4 days before the accident with normal compressions noted. Thus, the low compression during the postaccident examination was likely a result of the accident and the airplane remaining in an inverted position in the field for about 4 days after the accident.

When the temperature and dew point of the area surrounding the accident site were entered into a carburetor icing probability chart, the result was in the “moderate icing – cruise power” and “serious icing – glide power” category. When the pilot was asked how the carburetor heat was checked, she stated that she turned it on, saw a drop in engine rpm and immediately turned it off. Thus, the loss of engine power was likely due to carburetor icing that accumulated before and during the takeoff, and the pilot’s failure to apply carburetor heat when the engine speed began to decrease. The momentary application of carburetor heat before takeoff was likely not sufficient to reduce or eliminate the ice buildup.

Text from the NTSB. Open the NTSB docket for CEN21LA381 for the full record.