Incident Overview
On July 11, 2018, at 09:22 UTC, a Bombardier DHC-8-Q400 aircraft departed from Warsaw Chopin Airport (EPWA) on a scheduled flight to Ljubljana (LJLJ). After the landing gear was retracted, the red and orange indicators for the left main landing gear remained illuminated for approximately three minutes. In response, the crew decided to return to Warsaw. After burning off excess fuel, the aircraft landed without further incident.
Maintenance Findings
Following the landing, the crew notified the maintenance control center (MCC), and the aircraft was handed over to technical staff. During inspection of the landing gear retraction and extension system, a malfunctioning proximity sensor designated SI5 was identified. The sensor was replaced with a new unit, and a functional test of the landing gear system was successfully conducted.
Probable Cause
The investigation determined that the cause of the incident was a faulty proximity sensor.