Abstract: A method of transforming a fault tree diagram of an engineering system comprising a plurality of cut-set matrices and logic gates. Each column of the cut-set matrix corresponds to an event of the system, and each row of the cut-set matrix indicates a combination of occurred events. Each logic gate takes as input the cut-set matrices and/or outputs from other logic gates. The method includes selecting at least one logic gate that has as inputs only one or more cut-set matrices and determining a set of events corresponding to f the one or more cut-set matrices received by the selected logic gate. A replacement cut-set matrix for the selected logic gate is then determined and the selected logic gate is then replaced with the replacement cut-set matrix.