Event Summary
A flight instructor conducting an introductory flight for a passenger experienced a loss of engine power. The instructor referred to the emergency procedures checklist, and the engine temporarily regained power. However, the engine's performance then began to fluctuate, alternating between partial power and no power.
Flight Actions
Unable to maintain altitude, the flight instructor attempted to land at a nearby airport but was not able to reach it. He performed a forced landing to a snow-covered field. During the landing roll, the airplane nosed over.
Post-Accident Examination
Examination of the airplane and engine did not reveal any pre-impact mechanical malfunctions. Compression was attained on all cylinders, and a fuel sample did not reveal any contamination.