What happened
On August 24, 2016, an L-410 Turbolet was taxiing at Warsaw Chopin Airport (EPWA) in preparation for a ground-based navigation equipment test flight. During the taxiing phase, the crew observed smoke emerging from the left side of the cockpit, accompanied by the smell of burning.
In response to the smoke, the crew immediately decided to abort the taxiing procedure and returned the aircraft to its parking position. Following the incident, maintenance personnel conducted a thorough inspection of the aircraft's electrical system.
The investigation
The investigation focused on identifying the source of the smoke and the burning odor within the cockpit area. Technical personnel examined the electrical installations and identified a failure in the instrument panel lighting control component. Specifically, the investigation established that the winding of a potentiometer, used to regulate the brightness of the instrument panel illumination, had burned out.
Findings
- The primary cause of the incident was the burning of the potentiometer winding.
- The failure was most likely caused by operational wear and tear of the component.
- Following the replacement of the faulty potentiometer and subsequent functional testing, the aircraft was cleared for continued operation.