How do you visually confirm the landing gear is down and locked in the event of an indicator failure?

• A. Ball nut contacting the bumper stop
• B. Green landing gear indicator light on
• C. Gear handle in the down position
• D. Hydraulic system pressure within normal range

Answer: (A)

When indicator failure is possible, rely on a direct mechanical cue from the gear system itself. The ball nut contacting the bumper stop is a concrete, physical sign that the landing gear has reached full down and is locked. This stopping point happens as the locking mechanism engages, so the nut physically bears on the stop, confirming that the gear is fully extended and secured in place. This check is independent of any electrical indicators, making it the most reliable way to verify down and locked status when the indicator light or system isn’t trustworthy.

Relying on the green indicator light isn’t helpful when there’s an indicator failure, since that visual cue could be inoperative. The gear handle being in the down position reflects a commanded position, not the actual locked condition, so it doesn’t guarantee that the gear is truly locked. Hydraulic system pressure being normal doesn’t prove the gear is locked either, because a mechanical fault could prevent locking even with normal pressure.