Primary finding
Probable cause
A fire in the engine compartment due to over-priming.
Investigator assessment
Analysis narrative
It was a cold day, and as the airplane had been flown about 45 minutes to an hour earlier, the instructor did not pre-heat the engine. His three attempts to start the engine were unsuccessful, so he decided to pre-heat. He primed the engine, but this attempt was also unsuccessful, so two additional shots of prime were applied. By this time, the battery was ineffective, so the instructor decided that an external start was required. While exiting the airplane, the instructor noticed smoke coming from the cowling. He advised the student to vacate the area, and he shut off the fuel selector before leaving the area to get a fire extinguisher. By the time he had returned with an extinguisher, the fire had spread throughout the engine.
Source record
Factual narrative
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