Alternate gear extension uses which power sources?

• A. The primary hydraulic system.
• B. A manual or alternate hydraulic power source.
• C. A pneumatic power source only.
• D. Electrical power source only.

Answer: (B)

Alternate gear extension is designed to work when the normal hydraulic system isn’t available, so the gear can still be deployed using a backup source of hydraulic power. The system is built to be operated either by a manual pump used directly by the crew or by an alternate hydraulic power source that is independent from the primary hydraulic circuit. This keeps the gear extension hydraulics alive even if the main pumps fail.

Why this is the best fit: gear actuators require hydraulic pressure to move, and the backup approach must provide that pressure without relying on the primary system. A manual hand pump can supply the necessary pressure directly, and an alternate hydraulic source (which could be driven by electric or other means) provides the same hydraulic pressure through a separate circuit. This is different from relying solely on pneumatic power, which doesn’t supply the hydraulic pressure needed to extend the gear, and it’s not limited to electrical power alone, since the important factor is the hydraulic pressure, not the primary electrical or pneumatic source.