What happened
On February 23, 2018, a Bombardier DHC-8-402 was performing a scheduled flight from Chișinău (LUKK) to Warsaw (EPWA). During the approach to landing at Warsaw Chopin Airport at approximately 14:30 UTC, the crew initiated the landing gear extension procedure. After moving the landing gear lever to the gear down position, the crew observed that the nose gear had failed to lock in the extended position, indicated by a red nose gear light.
In response to the malfunction, the crew decided to execute a go-around. The crew then utilized an alternative landing gear extension method, which successfully deployed and locked the gear. Following the successful deployment, the aircraft completed a normal approach and landed without further incident. The aircraft was subsequently handed over to maintenance personnel, and an Air Safety Report (ASR) was filed.
The investigation
The investigation focused on why the nose landing gear door failed to open using the primary method. Technical inspections of the nose landing gear door opening and closing mechanism were conducted. During the analysis of the malfunction, maintenance crews identified a leak originating from the actuator component. It was also noted that this leak had not been detected during a separate maintenance task performed on February 22, 2018, which involved repairing a proximity sensor on the same mechanism.
Findings
- The primary cause of the failure to open the nose landing gear door via the standard method was the wear-induced malfunction of the nose landing gear door actuator (P/N 47830-1).
- A leak was identified within the actuator assembly.
- The leak was not visible or detectable during the previous day's maintenance work on the nose gear door proximity sensor.