During maintenance or parked, when is a ground lock installed on the landing gear?

• A. During flight to monitor gear.
• B. During maintenance or when parked to prevent gear retraction.
• C. During takeoff to assist extension.
• D. To secure the doors.

Answer: (B)

Ground locks are used to keep the landing gear from moving while the aircraft is on the ground or being serviced. They lock the gear mechanism (often by inserting a pin or similar device into the retraction linkage or gear doors) so the gear stays in the down and locked position during maintenance or when the aircraft is parked. This prevents accidental retraction due to hydraulic pressures, faults, or handling during storage and inspections. They must be removed before flight because leaving them in place would prevent gear retraction in flight, creating a dangerous gear-up situation. This isn’t something you’d install during flight or takeoff, and it isn’t used to secure the doors—its purpose is specifically to prevent gear movement while on the ground.