What is the required psi for Engine Bleed Air Valves operation?

• A. 10 PSI
• B. 13 PSI
• C. 15 PSI
• D. 20 PSI

Answer: (B)

Engine Bleed Air Valves open when the bleed pressure from the engine reaches a defined threshold, and that threshold is set to ensure reliable supply to the packs and other bleed-dependent systems without opening too early. On the CRJ-550, the specified activation pressure is 13 psi. This value is chosen so that once the engine produces bleed air, there is enough pressure to move the valve to the open position and deliver the air where it’s needed, while still allowing the system to modulate flow as demand changes. If bleed pressure is below this threshold, the valve remains closed to prevent ineffective flow; if it's above, the valve opens to supply the downstream systems. The other pressures listed don’t match the design setting for when the valve begins to operate on this airplane.