Prospective lines of improving the process of evaluating the technical condition of aircraft hydraulic system working fluid

The article is devoted to the evaluation of the technical condition of aircraft hydraulic system working fluids. Working fluid parameters (concentration of impurities, viscosity, density, anti-oxidation, anti-wear and thermal properties) determining its technical condition are selected on the basis of a study of scientific and technical literature. The peculiarities of the existing process of its evaluation are discussed. A structural grapho-analytical model reflecting the condition of the working fluid was developed. The model takes into account the influence of the fluid’s basic parameters as well as reachability and counter-reachability matrices. Analyzing the results, it was found that the graph components are strongly interconnected. Viscosity is closely linked with anti-wear and thermal properties, while variations in mechanical impurity content in the working fluid cause variations in the rest of its parameters. Thus, we can say that the assessment of the working fluid’s condition based on measuring only its purity and viscosity is not quite reliable. We substantiate the future line of research with the aim of developing new methods to assess the condition of the working fluid, namely, development of mathematical models of the working fluid condition taking all its components into account.