How does the APU assist in aircraft functionality during flight?

The auxiliary power unit (APU) is a crucial component of an aircraft that provides essential services when the main engines are not operating. One of the primary functions of the APU is to supply bleed air, which is vital for various systems on the aircraft. This bleed air is used for engine start, environmental control systems, and de-icing systems, ensuring the aircraft remains operational and comfortable under various conditions during flight.

Understanding the role of the APU in supplying essential bleed air highlights its significance in maintaining safe and efficient operations. The ability to generate bleed air independently allows the aircraft to start engines in flight, manage cabin pressure, and deliver environmental controls, thereby enhancing overall safety and performance.