On the ground, which statement best describes the GPU's role?

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

Answer: (C)

The main idea is that a ground power unit provides external power to the aircraft while it’s on the ground, so all systems can run for maintenance and preflight without drawing from the aircraft’s own batteries or needing to start the engines or APU. This lets you run avionics, lighting, climate control, and testing gear without taxing onboard power sources. While GPUs can also help recharge batteries, the essential function described is supplying power to the aircraft systems on the ground for maintenance and preflight without using onboard starting sources. The other options are either narrower (battery charging) or describe functions not associated with ground power units (emergency power during flight).