What is the role of external power (GPU) on the ground?

• A. To provide power to the aircraft systems for maintenance and preflight without using the aircraft’s batteries or starting sources.
• B. To power only the cockpit lighting.
• C. To recharge the battery only.
• D. To supply emergency power during flight.

Answer: (C)

External power on the ground supplies the aircraft’s electrical system so maintenance and preflight checks can be done without using the aircraft’s own batteries or starting sources. This allows avionics, instruments, lighting, environmental controls, and other systems to operate with the engines and APU off. While connecting ground power can also help recharge the battery, that isn’t its sole function—the power unit is there to run the whole electrical system on the ground. It isn’t used for emergency power in flight, nor is it limited to just charging the battery or lighting the cockpit.