How is the APU started?

How is the APU started?

• A. Via electrical power from the battery or an outside electrical source
• B. By turning a switch on the left wing
• C. By hydraulic power only
• D. By manual cranking

Answer: (A)

Starting the APU relies on electrical power to spin its starter motor. When the aircraft battery or an external ground power unit provides power, the electric starter turns the APU until it reaches operating speed and can ignite, becoming self-sustaining. Once running, the APU can supply electrical power and bleed air as needed for systems and engine starts. This is why electrical power from the battery or a GPU is the correct method. Using hydraulic power alone won’t start the APU, and manual cranking isn’t how modern APUs are started; there isn’t a simple switch on a wing used to start it in typical operations.

Starting the APU relies on electrical power to spin its starter motor. When the aircraft battery or an external ground power unit provides power, the electric starter turns the APU until it reaches operating speed and can ignite, becoming self-sustaining. Once running, the APU can supply electrical power and bleed air as needed for systems and engine starts. This is why electrical power from the battery or a GPU is the correct method. Using hydraulic power alone won’t start the APU, and manual cranking isn’t how modern APUs are started; there isn’t a simple switch on a wing used to start it in typical operations.