How are main gear actuators synchronized to ensure equal extension?

• A. Activated by electric motors that synchronize movement.
• B. Through hydraulic crossfeed, matched actuators, and valve timing to balance movement.
• C. With separate circuits for each main gear and no crossfeed to balance movement.
• D. By pilot manual control for each actuator.

Answer: (B)

The key is coordinating hydraulic flow and pressure so all main gear actuators move together. Hydraulic crossfeed links the actuator circuits on the same gear, so if one side starts to move a bit faster, fluid can shift to or from the other actuator to equalize speed and travel. This helps cancel out small differences in friction, stroke, or hose length that would otherwise cause one leg to extend sooner.

Using matched actuators means each unit has very similar characteristics, so they respond similarly under the same hydraulic conditions. Even tiny discrepancies can create unequal extension, so matching them keeps motion more uniform.

Valve timing ensures the fluid is delivered to all actuators in a synchronized way. Proper sequencing and control of the valves prevent one actuator from receiving flow earlier or longer than another, further aligning their movements. In combination with crossfeed and matched components, this yields equal extension and retraction of the main gear, preserving alignment and proper operation on touchdown.