This research develops an array of durable micro-machined valves capable of operating at frequencies in excess of 10 kHz. Standard lithographic process are used to manufacture metallic check valves on the order of 100 microns with an array contained within a centimeter area. The fundamental resonance frequency of the valves is above 20 kHz and the array provides flow rates in excess of 10 cc/s. An appropriate metallic material is used for increased tough and durability when compared to conventional MEMS materials (i.e. silicon). The program consists of analytically modeling the valve/material combination, predicting valve strength, predicting resonant frequencies, and predicting flow rate. Following the analysis, a prototype valve array will be manufactured and tested during the phase I effort. Testing the valve in a representative EHA system is performed during the phase II effort.