The paper describes the current technologies of multidisciplinary simulation being used in the aircraft gas turbine engine development. Two sets of examples are presented. The first example is aimed at a prediction of blade forced response using the system which consists of unsteady aerodynamic analysis for incoming gust response and aeroelastic modal analysis. The second example focused the prediction of flow and heat transfer in the multiple rotating cavities formed by the multiple discs of the HP (High Pressure) compressor with a rotating shaft running through the bores.