With a loss of control power, what will happen to the HPV, PRSOV, and APU LCV?

• A. Open to the air
• B. Fail to the closed position
• C. Remain in their last commanded position
• D. Move to the open position

Answer: (B)

When control power is lost, the electrical or electro-hydraulic actuation that holds these valves in their commanded positions no longer functions. These valves are designed with springs that bias them toward the closed position when power is unavailable. This fail-safe design prevents unintended hydraulic flow or actuation, so the HPV, PRSOV, and APU LCV will move to and remain in the closed position. They won’t remain in their last position or open on their own, because there’s no power to hold or drive them open.