The paper is devoted to developing a methodology for failure mode and effects analysis on the example of assessment of defects that occur during production and operation of polymer composite materials and industrial products from them. The paper uses the Ishikawa method to illustrate and further analyze the cause of defects in reinforced polymer composite material. The Ishikawa diagram was constructed and analyzed using the method of causal analysis. The types and consequences of failures and defects for polymer composite materials are analyzed. For each type of defect, the value of the priority number of risks is calculated. For the most critical defect, measures to reduce potential defects are proposed. Suggestions for improving the detected defective zones in the structures of polymer composites in the analysis process are given.