What happened
On July 11, 2018, at 09:22 UTC, a Bombardier DHC-8-Q400 departed from Warsaw Chopin Airport (EPWA) on a scheduled flight to Ljubljana (LJLJ). Shortly after takeoff and following the retraction of the landing gear, the crew observed that the red and orange position lights for the left main landing gear remained illuminated. This indication persisted for approximately three minutes.
In response to the warning, the crew decided to abort the flight and return to Warsaw. To ensure safety during the approach, the crew performed a fuel burn-off procedure to reduce the aircraft's weight before landing. The aircraft landed at EPWA without further incident or damage.
The investigation
The investigation focused on the landing gear retraction and indication systems. Following the return to base, the aircraft was handed over to maintenance personnel. During a technical inspection of the landing gear extension and retraction installation, technicians identified a malfunction in the SI5 proximity sensor. The faulty component was subsequently replaced with a new unit, and successful functional tests of the landing gear system were performed.
Findings
- The primary cause of the incident was a malfunction of the SI5 proximity sensor.
- The aircraft's safety management system (SMS) recorded the event, and it was integrated into the operator's safety performance indicators (SPI) for ongoing monitoring.