Which bus would power the listed cabin loads when the aircraft is on the ground and the GPU is active?

Which bus would power the listed cabin loads when the aircraft is on the ground and the GPU is active?

• A. Bus tie bus
• B. Main bus
• C. Ground service bus
• D. Essential bus

Answer: (C)

When the aircraft is on the ground with external power (GPU) connected, cabin loads are fed by the Ground Service Bus. This dedicated bus is designed to supply nonessential cabin equipment—lighting, galley gear, climate control, and other passenger comfort systems—while the GPU powers the aircraft. It keeps these loads separate from the essential flight-control bus and the main bus, which carry critical systems and most aircraft systems in flight. The bus tie is simply a switching path that can connect or isolate buses; it’s not the source of power itself. So the Ground Service Bus is the appropriate path to power cabin loads on the ground with external power.

When the aircraft is on the ground with external power (GPU) connected, cabin loads are fed by the Ground Service Bus. This dedicated bus is designed to supply nonessential cabin equipment—lighting, galley gear, climate control, and other passenger comfort systems—while the GPU powers the aircraft. It keeps these loads separate from the essential flight-control bus and the main bus, which carry critical systems and most aircraft systems in flight. The bus tie is simply a switching path that can connect or isolate buses; it’s not the source of power itself. So the Ground Service Bus is the appropriate path to power cabin loads on the ground with external power.