Incident Overview
On February 1, 2021, a Bombardier DHC-8-402 aircraft with registration SP-EQC was operating a passenger flight from Gdańsk (EPGD) to Warsaw (EPWA). Shortly after takeoff from Gdańsk, the pilot moved the landing gear lever to the "UP" position to retract the gear. In response, the three green gear position indicator lights extinguished and three red lights illuminated, accompanied by a "WT ON WHEELS" (weight on wheels) warning. The landing gear did not retract and remained in the extended position.
Crew Actions
The flight crew performed the procedures specified in the applicable checklists for this situation. When the gear lever was returned to the down position, the three green gear indicator lights immediately illuminated, confirming gear extension. After assessing the weather conditions (favorable wind direction and no icing) and fuel quantity (an additional 800 kg of fuel onboard), and after consulting with the lead flight attendant and the maintenance control center, the crew decided to continue the flight as planned and land at Warsaw.
Landing and Post-Flight Inspection
The landing at Warsaw was normal. Upon touchdown, the "WT ON WHEELS" alert extinguished. A subsequent inspection of the landing gear by maintenance personnel revealed that the unloaded nose landing gear (NLG) shock absorber did not fully extend. This caused the NLG proximity sensor to provide an erroneous signal indicating weight on the wheels while in flight. Consequently, the proximity switch electronic unit (PSEU), which controls gear retraction and extension, inhibited the gear retraction sequence.
Cause
The cause of the incident was incomplete extension of the unloaded nose landing gear shock absorber after takeoff, which prevented the initiation of the gear retraction sequence.
Contributing Factors and Recommendations
The investigation did not identify any contributing factors. No safety recommendations were issued.