Incident Details
On 24 August 2016, a Let L-410 Turbolet was taxiing at Warsaw Chopin Airport (EPWA) for a flight to perform a ground-based navigation aid calibration. During taxi, smoke appeared from the left side of the cockpit, accompanied by a smell of burning. The crew decided to discontinue the taxi and return the aircraft to its parking position.
Technical personnel subsequently inspected the aircraft's electrical system. They found that the winding of a potentiometer used for adjusting the instrument panel lighting had burned through. The potentiometer was replaced, and after a functional check, the aircraft was cleared for further operation.
Four persons were on board; none sustained injuries.
Cause
The burning of the potentiometer winding was most likely due to wear and tear from normal service use.
Preventive Measures
As a preventive measure, the technical condition of the remaining potentiometers on this aircraft and on another aircraft operated by the same user was checked. All were found to be in satisfactory condition. No safety recommendations were issued by the investigating body.