This SAE Aerospace Information Report (AIR) presents data on normally accepted changes in physical properties and contamination levels for military hydraulic fluids used in hydraulic test stands. This information is of importance to all users of hydraulic test stands to assure the performance data obtained on these test stands for specific components will not be adversely affected by excessive changes in fluid properties or contamination levels. The data pertains to fluids conforming to specifications MIL-PRF-5606, MIL-PRF-83282, and MIL-PRF-87257. The guidelines incorporated in the AIR are the general consensus values of knowledgeable professionals. However, the experience and judgment of engineers and operators responsible for the equipment must be relied upon to determine when the hydraulic fluid is to be replaced.
This document is being revised to update the specification numbers for the fluids, to add MIL-PRF-87257, and to delete the non-aerospace rust inhibited hydraulic fluids. In addition, a maximum allowable limit for barium is being added due to the problems experienced when barium gets introduced to the aircraft hydraulic system.