Abstract
Most papers concerning hydraulic systems contamination cover primarily the adverse effects of particulate contamination on hydraulic component and system performance. While that is a valid concern, the effects of other contaminants can also be serious. This paper concentrates on the adverse effects of water, free air, and chemical contaminants on military aerospace hydraulic component and systems performance. The hydraulic fluids used in the military aerospace systems are both the mineral oil-based MIL-PRF-5606 [1] and the synthetic hydrocarbon-based fire resistant hydraulic fluids MIL-PRF-83282 [2], and MIL-PRF-87257 [3]. Examples will be provided where each of the contaminants were responsible for some adverse effect and the recommended solution for the problems will be provided. Some of the problems encountered were stuck valves, spongy controls, “burnt” hydraulic fluid, and erratic actuator performance. The methodology used to identify the source of the problem will be presented. Based on the problems found, limits for these contaminants were recommended and, when followed, solved the problems for the aircraft involved. The major significance of this paper is to enlighten the aerospace hydraulic system community to the potential problems caused by contamination other than particulate contamination and to suggest solutions for these problems.
