This Aerospace Information Report presents an overview of the application and control of fixed and variable displacement pumps with the emphasis on the controls most commonly used on variable displacement pumps. It describes various options to control the operation of hydraulic pumps in terms of controlling the pump output pressure and/or flow and assisting in the selection of the pump. Purpose The information contained herein is intended to provide application information to assist system integrators in selecting the most appropriate pump controls for a given application. It can also be used as an introduction to pump designers. Field Of Application The controls described are applicable to hydraulic pumps installed on commercial and military aerospace applications. Additional details relating to design and performance characteristics of pumps in various aerospace applications are provided in the following documents: a. AS595 provides additional information on civilian aircraft pumps b. ISO8278 provides additional information on civilian and military aircraft pumps c. AS19692 and ARP560 provide additional information oriented toward general military and missile pumps@ respectively d. ISO22089 and ARP1280 provide additional information for controlling power transfer units e. AS5994 provides additional information on electric motor driven pumps