What happened
A commercial pilot and four passengers departed on a scheduled commuter flight in a single-engine airplane over an area characterized by wooded islands and open water. Approximately thirteen minutes into the flight, while the aircraft was in a climb, the pilot observed smoke and heat emanating from beneath the mid-cabin floor. The pilot declared an emergency, reporting an active fire on board.
To manage the situation, the pilot performed a ditching in shallow water along the shoreline of a small island. The fire, which was situated under the right front seat between the cabin floor and the lower belly skin, extinguished itself during the ditching process. All occupants were not injured.
The investigation
Post-accident examination of the aircraft revealed that a fuel line, a bundle of electrical wires, and a Loran antenna cable had been routed adjacent to each other under the cabin floor. This configuration was contrary to FAA recommended methodology. The Loran antenna cable had been installed ten years prior to the accident.
Investigators discovered two small holes in the fuel line that were consistent with electrical arcing. Evidence of arcing was also found on one of the electrical wires. The wire and antenna bundle were secured to plastic clamps using plastic tie wraps; these clamps were attached to fuselage formers via bolts or screws. One clamp, located adjacent to the holes in the fuel line, had become detached from its mounting point. A screw and a small melted portion of a plastic tie wrap were recovered from the fuselage belly beneath the cabin floor.
Maintenance records indicated that an annual inspection had been performed six months prior to the accident, and a 100-hour inspection had been completed 11 days before the event. The company's inspection checklists include examinations of antenna cables and the internal structure of the fuselage.