Fault tree analysis of hydraulic power-steering system

The historical development is presented in the introductory part and it points out the importance of using the Fault Tree Analysis (FTA) method for analysis of the reliability and safety of technical systems. By analysing a number of references related to the FTA method, a FTA methodology is established, whose algorithm, with explanation of some steps, is given in this paper. As an example of the practical application of the method, the fault tree of the hydraulic power booster of the steering system of light commercial vehicles is qualitatively analysed. Based on data from the development phase and through a team approach, a fault tree for hydraulic power steering was developed. Along with an explanation of certain parts of the fault tree, the estimation of significance of certain events is done and the possibilities are considered to eliminate causes of failure or to minimise the consequences of failure.