Piper PA-31-350 Navajo Chieftain, G-VIPP
During the climb after departure, the crew observed smoke in the cockpit and flames emanating from the overhead panel. All non-essential electrics were turned off and the aircraft returned to the departure airfield safely. There were no injuries. One of the air recirculation fans was found to have suffered a mechanical failure and there was evidence that its circuit breaker had failed to trip. The excessive current drawn by the fan had caused the wiring to overheat, producing the smoke and flames.