Background
Prior to departure, the pilot obtained a weather briefing that included a forecast of moderate icing and pilot reports of icing moving into the planned route of flight. The airplane was not approved for flight into known icing conditions.
Flight
Despite the briefing and the aircraft's lack of icing approval, the pilot elected to depart. En route, the airplane encountered airframe icing. The pilot requested a lower altitude and subsequently reported that the engine was losing power. Unable to maintain altitude, the pilot performed a forced landing in a wooded area.
Post-Accident Examination
An inspector from the Federal Aviation Administration (FAA) reported no evidence of a mechanical failure or malfunction with the airframe or engine. However, the spark plugs were found to be sooty, and the air filter was soaked with water.
Weather
A witness near the accident site reported fog and snow at the time of the accident.