If the left or right engine bleed air switch is turned OFF, what happens to bleed air sent to the pneumatic system?

If the left or right engine bleed air switch is turned OFF, what happens to bleed air sent to the pneumatic system?

• A. Bleed air continues to ECS from that side
• B. No bleed air is sent to the ECS from that side, but bleed air remains available to anti-ice
• C. Bleed air is redirected to the other side’s ECS
• D. Bleed air is completely blocked from both ECS and anti-ice

Answer: (B)

Bleed air distribution is split between environmental control (ECS) and anti-ice, with dedicated control paths for each side of the aircraft. When you turn off the bleed air switch for a given engine, the valve to the ECS side on that engine closes, so no bleed air from that engine goes to the ECS from that side. However, the anti-ice path is controlled separately, so bleed air from that same engine can still be available to anti-ice if commanded. That’s why the correct result is that no bleed air is sent to the ECS from that side, but bleed air remains available to anti-ice.

Bleed air distribution is split between environmental control (ECS) and anti-ice, with dedicated control paths for each side of the aircraft. When you turn off the bleed air switch for a given engine, the valve to the ECS side on that engine closes, so no bleed air from that engine goes to the ECS from that side. However, the anti-ice path is controlled separately, so bleed air from that same engine can still be available to anti-ice if commanded. That’s why the correct result is that no bleed air is sent to the ECS from that side, but bleed air remains available to anti-ice.