What is the role of the retract/extend actuator in a landing gear system?

• A. To damp vertical loads during landing.
• B. To provide hydraulic fluid to the brakes.
• C. To move the gear between extended and retracted positions.
• D. To illuminate gear status indicators.

Answer: (C)

The actuator’s job is to move the landing gear between extended and retracted positions. It’s usually a hydraulic cylinder that converts fluid pressure into linear motion, pushing or pulling the gear legs to unlock, fold, or deploy them as commanded. When extending, pressure drives the rod to push the gear into the down position and interface with the doors and down-locks; when retracting, pressure pulls the gear up into the wheel well and engages the up-lock to secure it. This motion is coordinated with the door mechanisms and locking hardware to ensure the gear is fully deployed for landing and securely stowed for flight. It isn’t the component that dampens vertical loads, supplies hydraulic fluid to the brakes, or provides gear status illumination.