Incident Summary
A pilot reported that during cruise flight with three passengers, a fire erupted under the cabin floor. The pilot used the airplane's handheld fire extinguisher to put out the fire. He then diverted to a closer airport and landed without further incident.
Examination Findings
FAA safety inspectors examined the airplane and determined the fire originated when an electrical wire bundle, located next to and touching a fuel line, abraded against the fuel line and arced. The electrical arc burned a hole in the fuel line, allowing fuel to leak. The leaking fuel ignited. The wire bundle was not supported, which allowed it to rub against the fuel line. According to the airplane's operator, the wire installation occurred prior to their acquisition of the airplane.
Probable Cause
An unsupported electrical wire bundle abraded against a fuel line, causing an electrical arc that burned a hole in the fuel line, leading to a fuel leak and subsequent fire.