Under what conditions is alternate gear extension used?

• A. When the primary hydraulic system or electrical gear extension fails; used to extend gear via a manual or alternate hydraulic power source.
• B. Wheel nuts are loose.
• C. Landing gear doors fail to close.
• D. Landing gear is retracted.

Answer: (A)

Alternate gear extension is a backup method used when the primary hydraulic or electrical gear-extension system is not available. In that situation, a manual or alternate hydraulic power source is engaged to extend and lock the landing gear and to open the doors, ensuring a safe landing despite a primary-system failure. Other scenarios like loose wheel nuts, doors not closing, or the gear already being retracted do not involve this backup extension capability.