How is the APU started?

• A. A DC starter motor
• B. An AC starter motor
• C. A battery start procedure
• D. Ground power start

Answer: (A)

Starting the APU relies on an internal starting device that first spins the turbine up to speed. The typical setup uses a DC starter motor powered by the aircraft’s electrical system (or a battery). This DC motor provides the initial torque needed to bring the APU up to its light-off speed; once fuel is introduced and ignition occurs, the APU becomes self-sustaining and can continue running to supply bleed air and electrical power. The other methods listed aren’t the standard self-contained start method for most APUs, which is why a DC starter motor is the correct answer.