What happened
During a scheduled air taxi operation, an aircraft carrying five passengers departed for its destination. Shortly after takeoff, the pilot detected the smell of an electrical burn. In response to this odor, the pilot decided to abort the flight and return to the departure airport. Approximately one minute later, the smell of burning electrical components became more intense, and smoke became visible within the cockpit, prompting the pilot to declare an emergency to the control tower.
Following a successful landing, the passengers were evacuated from the aircraft without injury. Once the cabin was empty, thick smoke filled both the cockpit and the passenger area. The pilot observed a flame, described as being similar to a candle, originating from beneath the floorboards located behind the pilot and co-pilot seats. Shortly after this observation, the entire aircraft was consumed by flames.
Findings
An investigation into the airframe following the accident determined that the fire originated in the area behind the pilot's row of seats. Investigators discovered that a wire harness had been incorrectly installed directly on top of the aft fuel line leading from the left fuel tank. The examination of the harness showed thermal and electrical damage patterns that were consistent with chafing caused by the fuel line. The investigation concluded that the improper installation of the wire harness allowed it to contact the fuel line, leading to chafing and electrical arcing, which ultimately ignited the fire.