Accident Details
The pilots reported that the airplane experienced a partial loss of engine power and collided with trees during an off-airport emergency landing. Both the certified flight instructor (CFI) and the student noted that the engine was running rough, "like a rough running magneto" as the airplane climbed over a ridge line. The engine was producing power, but not enough to sustain flight, and the airplane started to sink. The CFI executed a forced landing and collided with trees in the mountainous terrain.
Pilot Reports
The CFI and student both described the engine roughness as similar to a rough running magneto during the climb. The partial power loss was insufficient to maintain altitude, necessitating the forced landing.
Examination Findings
A carburetor icing chart indicated that moderate icing conditions were favorable at the time of the incident. Detailed examination of the fuel system disclosed no discrepancies in the tanks, lines, carburetor, or the vent system. The engine was mounted in a test stand and ran throughout the complete range of power output from idle to full with no anomalies found.