In the event of a landing gear indicator failure, which mechanical condition confirms the landing gear is down and locked?

• A. Ball nut contacting the bumper stop
• B. Nose gear audible chirp
• C. Gear doors open
• D. Hydraulic pressure drop

Answer: (A)

The key idea is a positive, physical proof that the gear is fully extended and the lock is engaged, which remains valid even if the normal indicators fail. When the gear reaches its full travel and the locking mechanism engages, a ball nut seats against a bumper stop. This contact is a tangible, mechanical indication that the gear is down and locked, independent of electrical signals or status lights.

Other signs like an audible chirp, gear doors opening, or a hydraulic pressure drop aren’t as reliable for confirming the locked position. An audible chirp can vary or fail, doors opening may occur due to unrelated door faults, and a pressure drop simply shows hydraulic status rather than the actual gear position.