What controls the landing gear?

• A. Proximity Sensing Electronic Unit (PSEU)
• B. Hydraulic Control Unit
• C. Flight Control Computer
• D. Gear Steering Computer

Answer: (A)

The system that decides when and how to move the landing gear is the electronic control unit that processes gear-related signals. In the CRJ‑550, the Proximity Sensing Electronic Unit takes inputs from the landing gear handle and from gear-position sensors to determine the current gear status and to issue the appropriate commands. It coordinates the sequence of actions (doors, extension, and locking) and ensures safe operation, such as preventing retraction if the gear isn’t fully down and locked. The actual movement is carried out by the hydraulic system, which carries out the commands once the PSEU directs it. The other components—Hydraulic Control Unit provides the hydraulic power and valve actuation, the Flight Control Computer handles flight surfaces, and the Gear Steering Computer manages nose-wheel steering—not the overall control logic for gear deployment.