With the X Bleed switch in AUTO, the engine bleed valves will be ____________ when the APU bleed valve is open.

With the X Bleed switch in AUTO, the engine bleed valves will be ____________ when the APU bleed valve is open.

• A. Open
• B. Off
• C. Closed
• D. Partially open

Answer: (C)

Bleed-air sources are kept separate and controlled automatically so only one source feeds the system at a time. When the APU bleed valve is open, the engine bleed valves are closed to prevent bleed air from the APU circulating into the engine bleed ducts or back into the engine. This isolation ensures the APU bleed air goes to the packs or the intended cross-bleed path as needed, without mixing sources. So, with the X Bleed switch in AUTO and the APU bleed valve open, the engine bleed valves are closed.

Bleed-air sources are kept separate and controlled automatically so only one source feeds the system at a time. When the APU bleed valve is open, the engine bleed valves are closed to prevent bleed air from the APU circulating into the engine bleed ducts or back into the engine. This isolation ensures the APU bleed air goes to the packs or the intended cross-bleed path as needed, without mixing sources. So, with the X Bleed switch in AUTO and the APU bleed valve open, the engine bleed valves are closed.