Incident
The airplane sustained substantial damage when it collided with trees and terrain during a forced landing. The pilot executed the forced landing after experiencing a loss of engine power.
Pilot Report
The pilot reported obtaining a weather update prior to the flight, which indicated light snow and forecast icing conditions below 10,000 feet. He stated that the potential for icing did not suggest the flight could not be safely conducted. Approximately 20 minutes into the flight, while at cruise power and an altitude of about 7,000 feet, the airplane began to lose manifold pressure and the engine started to sputter. The pilot noted that he was losing power, airspeed, and altitude. He applied full carburetor heat, but the loss of engine power persisted. Subsequently, he performed a forced landing in a wooded area and was unable to find a clearing during the attempt.
Post-Accident Examination
Examination of the airplane after the accident revealed that the right magneto would not produce a spark. When the magneto was rotated, the contact point was observed to open and close. The spark plugs were found to be black and sooty. The air filter element was wet, and water could be wrung from it. Additionally, water was present in the filter housing. The carburetor heat control was found in the off position.
A Federal Aviation Administration Advisory Circular (AC) regarding impact ice indicates that such ice forms when moisture-laden air at temperatures below freezing strikes and freezes on parts of the airplane. The AC states that pilots should be particularly alert for icing when flying in snow, sleet, rain, or clouds, and that it is usually preferable to use carburetor heat or alternate air as a means of ice prevention rather than as a deicer, because fast-forming ice that is not immediately recognized by the pilot may significantly lower the amount of heat available from the carburetor heating system.
Weather Conditions
The weather conditions recorded at the airport nearest the accident site included light snow, freezing fog, a temperature of minus 1 degree Celsius, and a dew point of minus 3 degrees Celsius.