What is a common on-ground test for gear doors?

• A. Visual inspection only.
• B. Fly the aircraft at altitude to test door seals.
• C. Apply full throttle to test door dynamism.
• D. Manual cycling of doors through their travel to confirm smooth operation and proper sealing.

Answer: (D)

On-ground checks for gear doors focus on verifying that they operate smoothly and seal properly. The standard method is to manually cycle each door through its travel—fully open and fully closed and back again—while the aircraft is secured on the ground. This reveals any binding, roughness, or misalignment in hinges, actuators, and linkages, and confirms that the latches engage and the seals compress evenly when closed. Visual inspection alone can miss hidden issues in the mechanism or sealing surface, and testing at altitude or with high power isn’t appropriate for validating ground operation and could be unsafe. Manual cycling on the ground is the practical, effective way to catch problems before flight.