What does the APU also supply during flight?

• A. Only hydraulic power
• B. Sink power for electronic instruments
• C. Emergency electrical and hydraulic power
• D. Cargo loading assistance

Answer: (C)

The Auxiliary Power Unit (APU) is a crucial component in aircraft that provides auxiliary power while the main engines are not running. Specifically, during flight, the APU supplies emergency electrical and hydraulic power, ensuring that essential systems remain operational in case of main engine failure or during in-flight emergencies.

This capability is vital for maintaining control over various aircraft functions, such as flight instruments, control surfaces, and other critical systems that rely on hydraulic power and electrical systems. The APU ensures that in the event of an emergency, the aircraft can sustain operations and safely manage situations until a landing can be made.

In contrast, relying solely on hydraulic power without the electrical support might not maintain critical systems, nor does the APU serve the purpose of providing sink power for electronic instruments or assist with cargo loading, roles that are outside its primary design and function.