Incident Overview
Shortly after takeoff for an after-maintenance test flight, the pilot observed a fire in the left engine. The pilot reduced power and successfully landed the aircraft on the remaining runway without further incident. After landing, the engine and systems were shut down before the pilot and a passenger evacuated the aircraft.
Fire Response and Inspection
Fire personnel responded and applied a small amount of foam to the engine, which at that time was emitting smoke. Upon inspection, the fire was found to be confined to the accessory section of the engine. Heat damage was noted on the outboard nacelle web assembly, and the top wing skin beneath the nacelle was warped.
Cause Determination
Further inspection revealed that an electrical arc in the alternator wiring, caused by chafing against a pneumatic tube, was responsible for igniting the fire. The source of fuel was most probably accumulated fuel vapor from a fuel cell leak. This leak had been an ongoing maintenance discrepancy for approximately three weeks preceding the accident and was eventually corrected.
The aircraft was evacuated safely, and no further incidents were reported.