What is a ground lock and when is it used?

• A. A mechanical device that locks the gear in the extended position for maintenance or when parked to prevent retraction.
• B. A device to lock wheels during towing.
• C. A sensor to measure gear wear.
• D. An emergency door interlock.

Answer: (A)

A ground lock is a mechanical device that locks the landing gear in the down and locked position, used when the aircraft is on the ground for maintenance or when parked to prevent retraction. It keeps the gear extended if hydraulic pressure is lost or if there are system faults, allowing safe access for servicing and for stable towing or parking. It is removed before flight so the gear can retract normally.

The other options describe things that don’t match this purpose: locking wheels during towing would be wheel chocks or a tow pin, a sensor to measure gear wear is a wear or position sensor, and an emergency door interlock is unrelated to landing gear.