AAIB investigation to Beechcraft 300 Super King Air, SE-KOL
Smoke in cabin due to overheated flap motor at Farnborough Airport on 13 November 2014.
Summary:
It was intended that the aircraft would perform a ferry flight to return to Sweden. During engine start, the crew detected an electrical smell in the cabin. The co-pilot left the cockpit to try to locate the source of the odour and returned shortly after, to report that there was smoke coming from below the floor aft of the main wing spar. The smoke had increased and was now starting to impair visibility so the commander declared an emergency and ordered an evacuation. The fire services attended promptly and, using infra-red equipment, detected a heat source below the floor where the smoke had been observed. A technician later identified the source as the electrical flap motor.
The flaps had overtravelled such that they were hard against their mechanical UP stop and it was evident that the motor had overheated until the circuit breaker eventually tripped. The motor, limit switch and flap control relay were all changed and the system re-rigged but the repairer does not know which of these may have been responsible for the overtravel condition.
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