Incident Overview
On a cold day, an instructor pilot attempted to start an airplane that had been flown approximately 45 minutes to an hour earlier. The instructor did not pre-heat the engine before the first three starting attempts, all of which were unsuccessful.
Sequence of Events
After the failed attempts, the instructor decided to pre-heat the engine. He primed the engine and attempted to start it again, but this attempt was also unsuccessful. Two additional shots of prime were then applied. By this time, the battery had become ineffective, prompting the instructor to decide that an external start was necessary.
Fire Discovery
While exiting the airplane to arrange for an external start, the instructor noticed smoke coming from the cowling. He immediately advised the student pilot to vacate the area and shut off the fuel selector before leaving to obtain a fire extinguisher.
Fire Progression
By the time the instructor returned with the fire extinguisher, the fire had already spread throughout the engine compartment.