Differentiate gravity extension from emergency hydraulic extension.

• A. Gravity extension uses an alternate power source or manual mechanism to extend gear.
• B. Gravity extension uses aircraft weight to lower gear without hydraulic power; emergency hydraulic extension uses an alternate power source or manual mechanism to extend gear.
• C. Both rely on gravity to open doors.
• D. Gravity extension uses electric motors to extend gear.

Answer: (B)

Gravity extension relies on the aircraft’s weight to move the landing gear into the down position after the uplocks are released, so no hydraulic power is needed to lower the gear. This means the gear simply drops into place under gravity, and the doors and links are designed to accommodate that movement without relying on hydraulic pressure.

Emergency hydraulic extension, in contrast, is a back-up method used when the normal hydraulic system isn’t available. It uses an alternate power source or a manual mechanism to provide the necessary force to extend the gear and lock it down. This ensures the aircraft can land safely even if the primary hydraulics fail.

So the statement that gravity extension uses aircraft weight to lower gear without hydraulic power, while emergency hydraulic extension uses an alternate power source or manual mechanism to extend gear, accurately captures the distinction.