The analysis of the types and consequences of potential defects in engineering products based on the application of the theory of fuzzy sets is considered. The formulas of the corresponding linguistic variables are proposed. The calculation of the risk priority number based on mathematical operations with fuzzy numbers is given. The experimental verification of the proposed refined method of FMEA-analysis was carried out by the authors in order to improve the design of the car steering hydraulic booster. The use of elements of fuzzy sets theory in the FMEA procedure made it possible to move to such a powerful decision-making tool as a fuzzy logical conclusion, which is an approximation of the "inputsoutputs" relationship based on linguistic statements "ifthen" as well as logical operations on fuzzy sets.