What happened
On April 2, 2017, at approximately 11:30 UTC, a DH8D aircraft was taxiing on taxiway E at Warsaw Chopin Airport (EPWA) preparing for takeoff from runway 2/20. During the taxi phase, the crew observed a warning light indicating that the nose gear door was open. Consequently, the crew decided to abort the departure and returned the aircraft to parking stand 43B. Passengers were disembarked and moved to the terminal to await a replacement aircraft.
The investigation
Following the return to the stand, technical crews inspected the aircraft and identified a malfunction in the proximity sensor within the nose gear door closed sensor system. Maintenance personnel replaced the faulty proximity sensor and its associated wiring, and subsequently performed the necessary adjustments. Following these repairs, the warning light functioned correctly, and the aircraft was cleared for further service. The issue did not recur during subsequent operations.
An analysis of the failure was conducted to determine if the existing maintenance program was sufficient. The investigation noted that sensor performance is verified through periodic inductance measurements performed before and after the winter season to identify sensors with deviating parameters. The investigation established that this was the first instance of such a failure in this specific system during the current year.