The ground compressed air and the APU air are applied to which side of the pneumatic system?

The ground compressed air and the APU air are applied to which side of the pneumatic system?

• A. Right
• B. Left
• C. Top
• D. Bottom

Answer: (B)

Ground compressed air and APU air are applied to the left side of the pneumatic system. This left-side entry is reserved for external air sources so they can pressurize the system when engines are off or during APU operation, enabling engine starts and air conditioning/pressurization without relying on engine bleed. When the engines are running, bleed air from the engines feeds the right side of the system, providing the primary supply there. A cross-bleed valve between the sides allows air to be shared if needed, but the external sources (ground and APU) are intentionally connected to the left side.

Ground compressed air and APU air are applied to the left side of the pneumatic system. This left-side entry is reserved for external air sources so they can pressurize the system when engines are off or during APU operation, enabling engine starts and air conditioning/pressurization without relying on engine bleed. When the engines are running, bleed air from the engines feeds the right side of the system, providing the primary supply there. A cross-bleed valve between the sides allows air to be shared if needed, but the external sources (ground and APU) are intentionally connected to the left side.