Which mechanism is described as holding the Main Landing Gear in the up and locked position?

• A. A mechanical uplock
• B. Hydraulic lock
• C. Electrical latch
• D. Pneumatic pin

Answer: (A)

Holding the main landing gear up and locked relies on a positive, mechanical lock built into the gear bay called a mechanical uplock. When the gear retracts, a spring-loaded uplock catches the gear leg or a corresponding feature, locking it in the stowed position to resist aerodynamic loads, vibrations, and any residual forces acting on the gear. This lock is designed to remain engaged throughout flight and does not depend on hydraulic pressure to stay in place, which is crucial in case of a hydraulic failure. The retraction sequence includes releasing this uplock as the gear moves to its stowed position, but once engaged, it provides a robust, mechanically driven hold that keeps the gear securely up. Hydraulic lock serves a separate role in some systems to prevent actuator movement if hydraulic pressure is lost, but it isn’t the mechanism that physically holds the gear up and locked. The other options aren’t standard primary devices for this purpose, as electrical latches and pneumatic pins aren’t the primary retainers for the main gear in the up position.