What is the function of the uplock in landing gear?

• A. To dampen wheel shimmy.
• B. To register gear down status.
• C. To house hydraulic reservoirs for the gear system.
• D. To secure the gear in the extended position and prevent inadvertent retraction by latching the leg in place until a retraction command is given.

Answer: (D)

In landing gear systems, the uplock acts as the latch that secures the gear leg in the extended position. Once the gear has deployed, the uplock engages a hook or catch to hold the leg in place, preventing any inadvertent retraction due to aerodynamic loads, vibrations, or other forces. This locking stays in effect until a deliberate retraction command is issued, at which point the retraction sequence releases the uplock and allows the gear to fold back into the bay. This mechanism works together with the downlock to ensure the gear remains safely deployed when needed and only retracts when commanded.