Final answer:
The operation of the APU is automatic after the APU switch is turned ON, but it can be controlled and adjusted manually by the pilots. The APU provides electrical power and drives the aircraft's systems when the main engines are not running.
Step-by-step explanation:
The statement is true. The APU (Auxiliary Power Unit) is a device found on aircraft that provides electrical power and drives the aircraft's air conditioning and pneumatic systems when the main engines are not running. After the APU switch is placed ON, the operation of the APU is indeed automatic.
Once the APU switch is turned ON, the APU starts its automatic sequence, which includes self-checks and monitoring. The APU will begin to spool up, stabilize its speed, and then start generating electrical power and supplying the necessary services to the aircraft, such as air conditioning and hydraulic pressure.
While the APU operates automatically, it is still monitored by the pilots and can be controlled and adjusted manually as needed. The APU can be turned OFF if there are malfunctions or if it is not required during a particular stage of flight.