This paper proposes an integrated system’s approach towards design of aero-engine subsystems - seals, bearing chamber, generator and power system. In a conventional design approach, the design of the overall system is typically broken-down into subsystems. Therefore, the focus is not on the mutual interaction between different components or subsystems, resulting in a lack of characterization of the overall system performance at the design phase. A systems design approach adopts a much broader outlook, focusing on the overall optimization of the system performance. This paper is divided into two parts. The first part presents an integrated approach for modelling the electrical, mechanical and hydraulic subsystems of aero engines, in order to analyze the fluid dynamics interactions and reduce the transversal shaft vibrations. For this, an in-line starter/generator and an air-riding seal are studied. The two systems are co-related to each other through shaft transverse vibrations which tend to negatively affect the performance and stability of the seal. Moreover, a reduction of leakage flow through the seal influences the operation of the bearing chambers. The second part of the paper studies the minimization of the torsional vibrations of the shaft due to an electromechanical interaction with the electrical power system. As a result, the combined strategies presented in this paper introduce a method of study to improve the overall efficiency of the engine.