An automated particulate contaminant injection and control module that controls the level of contamination in the hydraulic fluid passing to a component, system or sub-system under test and removes the injected particulates upon return to the parent test stand. Using the pressure and flow of clean hydraulic fluid from the parent test stand, the contamination module prepares a concentrated contaminant slurry and injects it at a rate determined by a feedback signal from an in-line contamination sensor and an internal control algorithm.