This SAE Aerospace Recommended Practice (ARP) establishes the requirements for the design, manufacture, and qualification of four hydraulic switching valves used in airborne applications. Two are pressure operated, Type IA and IB and two are solenoid/pilot operated, Type IIA and IIB. They are applicable to four pressure classes 3000, 4000, 5000 and 8000 psi. The equipment as designed is intended to be installed in hydraulic systems designed to AS5440 for military applications or ARP4752 and ARP4925 depending on the type of aircraft for commercial applications. Additional or refined requirements shall be contained in the detail (procurement) specification and these shall take precedence over any potentially conflicting requirements of this ARP or documents referenced by this ARP.
This document provides guidance for the design and qualification test requirements for switching valves. These valves are typically utilized to provide secondary hydraulic power to circuits, whose primary supply source has failed. Also included is section covering relevant "Lessons Learned".