Prediction of Service Life of Aviation Hydraulic Fluids Based on Phosphate Esters

Abstract

The thermal stability and kinetics of change in acid numbers of phosphate-ester-based aviation hydraulic fluids with various dissolved water contents are studied. It is shown that the service life of such hydraulic fluids shortens several times if they are used at temperatures above 100°C and dissolved water contents above 0.5%. The critical concentrations of the anticorrosion additive at which its functional effectiveness is inadequate are determined. Accelerated tests using the proposed method can evaluate the effectiveness of the anticorrosion additive and predict the expected service life of phosphate-ester-based hydraulic fluids under the proposed application conditions.