CEN23LA036 · Cessna 152

According to the flight instructor, the airplane was in cruise flight when the engine rpm dropped from about 2,400 to about 1,300. He took the flight controls from the student pilot, turned on carburetor heat, and used the checklist in an attempt to restore power. According to the flight instructor, while trying different throttle and mixture settings, the rpm increased to about 1,500 for about 10 seconds before reducing back to 1,300. According to the student pilot, after the engine rpm reduced to 1,300, the flight instructor applied carburetor heat, and the engine rpm reduced and then increased briefly. The instructor notified air traffic control of the power loss and diverted to the nearest airport. When he realized they would not be able to reach the airport, he selected a field for a forced landing. During the landing, the nosewheel dug into the soft soil, and the airplane flipped over, which resulted in substantial damage to the vertical stabilizer and rudder. A postaccident examination of the engine and airframe revealed no mechanical malfunctions or anomalies that would have precluded normal operation. Based on the Federal Aviation Administration (FAA) carburetor icing probability chart, the atmospheric conditions at the time of the accident were conducive to the development of serious carburetor icing at glide and cruise power. Therefore, it is likely that the loss of engine power was due to the formation of carburetor ice. Although the engine power increased briefly when the flight instructor applied carburetor heat, it is likely the amount of ice was too much for the carburetor heat to overcome.

Verbatim NTSB analysis and probable cause from the NTSB dataset