Effects of Contamination on Hydraulic Pumps

This paper describes a program whose first objective was to obtain data on the effect of hydraulic fluid contaminants on the operation of a typical aircraft hydraulic pump from the point of view of contaminant concentration by weight, by particle size, and by type of contaminant. A second objective was to evaluate the methods used to determine contaminant concentration and a method suited to field use was to be recommended.

The paper describes the tests performed and gives maximum allowable values for contaminant weight, size, and hardness. Two alternate field contamination test methods are recommended and the weakest point for pump contamination tolerance is discussed.