In addition to generating power, what is another purpose of the APU?

The Auxiliary Power Unit (APU) serves multiple important functions in an aircraft beyond just generating power. One of its primary roles is to provide air conditioning and pressurization, as well as to assist in engine start procedures.

During ground operations, especially before engine start-up and while the aircraft is stationary, the APU can supply the necessary bleed air for the environmental control systems, which manage cabin comfort and ensure that the aircraft's interior is properly pressurized. This is crucial for passenger comfort and safety. Additionally, the APU provides the high-pressure air required to start the main engines, particularly when the aircraft’s engines are not yet running.

While emergency power, fuel management, and structural support are essential considerations in aviation, those functions are either secondary or unrelated to the primary roles that the APU fulfills.