Reliability is a critical feature for most vehicles, and particularly for aircrafts. In aircrafts, reliability may be improved using redundancy of components. Should one component fail, a backup is available. This strategy, however, causes reliability to be inversely proportional to desired costs and to desired overall weight. That is to say, the more redundancy is included in a design, the greater the costs and the greater the weight of the aircraft. As it is also desirable to maintain both costs and weight relatively low, there is a need for improvement to aircraft engine systems that would allow reliability to be increased without negatively affecting costs and weight.