Do the generators or the GPU have priority?

Do the generators or the GPU have priority?

• A. GPU
• B. Engine-generators
• C. Batteries
• D. APU

Answer: (A)

External power from the GPU takes priority. When a GPU is connected on the ground, it powers the aircraft’s electrical buses first, so you can run avionics, lights, and start the APU or engines without needing the engine-driven generators. The engine generators are used only if external power isn’t available or isn’t sufficient. The APU serves as a secondary power source when needed, such as starting engines or providing power if external power isn’t present, but it isn’t the first source you rely on on the ground. Batteries are a limited backup for essential systems and won’t support the full electrical load for an extended period.

External power from the GPU takes priority. When a GPU is connected on the ground, it powers the aircraft’s electrical buses first, so you can run avionics, lights, and start the APU or engines without needing the engine-driven generators. The engine generators are used only if external power isn’t available or isn’t sufficient. The APU serves as a secondary power source when needed, such as starting engines or providing power if external power isn’t present, but it isn’t the first source you rely on on the ground. Batteries are a limited backup for essential systems and won’t support the full electrical load for an extended period.