This SAE Aerospace Recommended Practice (ARP) is intended as a guide to aid in the specifying and testing of direct acting three way, two position, single and multiple coil, normally open and normally closed solenoid valves used for the pilot actuation of hydraulic control systems and the control of hydraulic components. The information presented should be useful in standardizing terminology, in specifying requirements and performance parameters, and in defining test methods. The recommendations do not restrict or attempt to define the internal design features of solenoid valves. Standard mechanical, electrical and fluid porting interfaces are recommended to provide commonalty, interchangeability, design flexibility and to be more affordable. In general, this recommended practice is directed toward solenoid valves for use in military and commercial flight control and hydraulic actuation systems.