What is the primary purpose of the auxiliary power unit (APU) in the ERJ?

The auxiliary power unit (APU) in the ERJ plays a critical role in supporting various functions of the aircraft when the main engines are not operating. The primary purpose of the APU is to provide electrical power and bleed air. This capability allows it to supply necessary power for starting the main engines, as well as for onboard systems while the aircraft is on the ground. Additionally, the APU can provide bleed air for various pneumatic systems, which is crucial for air conditioning and engine start processes.

Using the APU enhances operational efficiency during ground operations by enabling the aircraft to maintain essential systems without needing to run the main engines, thus conserving fuel and reducing wear on the engines. The versatility of the APU in delivering both electrical and pneumatic resources makes it an indispensable component of the ERJ's ground operations.