P25-349A-450 - Textron Aviation OEM Relief Valve

P25-349A-450 – Textron Aviation OEM Relief Valve

Available now on the Airparts.aero Marketplace.

Overview

The P25-349A-450 is a genuine OEM, high-precision pressure relief valve, a flight-critical safety component engineered for the hydraulic systems of Textron Aviation aircraft, particularly the Cessna Citation series. Manufactured by industry leaders like Circle Seal Controls to Textron's exact specifications, this valve is designed to act as an automatic safeguard against system over-pressurization. It continuously monitors system pressure and, should it exceed a factory-set limit of 450 PSI, the valve opens to relieve excess pressure, protecting lines, actuators, and other critical components from damage.

Key Features

• Automatic Over-Pressure Protection: Its primary function is to act as a passive safety device. It automatically opens to vent hydraulic fluid when system pressure exceeds its cracking pressure, preventing the catastrophic failure of hydraulic lines, seals, and components.
• Precise Cracking Pressure: Factory set and calibrated to a precise "cracking pressure" of 450 PSI. This ensures the valve only actuates when a true over-pressure event occurs and does not interfere with normal system operation.
• Zero-Leak "Bubble-Tight" Seal: Engineered for zero internal leakage ("bubble-tight") right up to its cracking pressure. This ensures system pressure and fluid volume are maintained perfectly during normal operations, preventing pressure bleed-down.
• High-Reliability Reseating: After relieving an over-pressure event, the valve is designed to reseat positively at a pressure slightly below the cracking pressure, restoring the hydraulic system's integrity for continued safe operation.
• Stainless Steel Construction: Machined from high-grade stainless steel, providing superior corrosion resistance and compatibility with all standard aviation hydraulic fluids, including MIL-H-5606 and Skydrol.

Technical Specifications

• Part Number: P25-349A-450
• Component Type: Pressure Relief Valve
• OEM Manufacturer (Typical): Circle Seal Controls
• Material: Stainless Steel
• Cracking Pressure: 450 PSI
• Reseat Pressure: Typically >90% of cracking pressure
• Sealing: Zero-leak up to 95-98% of set pressure
• Application: Aerospace Hydraulic Systems
• Certification: FAA Production Approval

Aircraft Compatibility

The P25-349A-450 is a key safety component in the high-pressure hydraulic systems of various Cessna Citation business jets. It is imperative to consult the specific aircraft's Illustrated Parts Catalog (IPC) for final verification.

• Primary Aircraft Models:
  • Cessna Citation Series (various models)

Applications

The P25-349A-450 is a critical safety device within the aircraft's hydraulic power system:

• System Protection: The primary safeguard against pressure spikes caused by thermal expansion of the fluid, pressure surges from the hydraulic pump, or the rapid actuation of a large hydraulic component.
• Component Overhaul: A key component to be tested, calibrated, or replaced during the overhaul of a hydraulic power pack or system.
• Troubleshooting: Inspected and tested when diagnosing issues of fluctuating or excessive hydraulic system pressure.

Why Choose P25-349A-450?

The hydraulic system operates landing gear, flaps, and flight controls on many aircraft. A system failure due to over-pressurization would be a critical emergency. The P25-349A-450 relief valve is the simple, highly reliable device that prevents this from happening. Using a genuine OEM-specified part is the only way to ensure the valve is calibrated to the correct pressure setting for your specific aircraft system. For a component this vital to the safety of the entire hydraulic system, there is no substitute for a genuine, certified part.

Order Your P25-349A-450 Relief Valve Now

Protect your aircraft's critical hydraulic systems with a genuine, factory-calibrated safety component. Visit Airparts.aero to order your P25-349A-450 pressure relief valve today.

The P25-349A-450 is a direct-acting relief valve. Inside the valve body, a precisely calibrated spring holds a poppet or ball firmly against a seat. The force exerted by the spring (​​) is greater than the force exerted by the hydraulic fluid at normal operating pressure (, where P is pressure and A is the area of the poppet exposed to the pressure). When the system pressure rises, $$F_{hydraulic}$$increases. At the moment system pressure reaches 450 PSI, $$F_{hydraulic}$$becomes greater than$$F_{spring}$$, forcing the poppet off its seat. This opens a path for the excess fluid to be vented, typically back to the main hydraulic reservoir, until the pressure drops enough for the spring force to reseat the poppet, sealing the valve once again.

Note: This is a flight-critical safety component. Installation must be performed by a certified A&P mechanic. The cracking pressure is factory-set and should not be adjusted in the field. The valve must be installed in the correct orientation to properly sense system pressure.

Use in Air Conditioning of Beechcraft 58 Aircraft