Redundancy management of fault tolerant aircraft system architectures – reliability synthesis and analysis of degraded system states

The draft process for aircraft system architectures of modern commercial aircraft is getting more and more complex. This is due to the growing demands on safety and reliability with simultaneously growing requirements on function and performance. As these stipulations are in contrast to each other, and the design period is linked with a tight time and cost boundaries, computer-aided methods and processes are required even in the early phase of system development. This article shows the stage of development of the software tool SyRelAn™ (System Reliability Analysis), which offers a platform for the synthesis and analysis of complex and embedded hardware and software systems to engineers of various technical backgrounds. The system is based on hybrid system model with structure-oriented modeling of the architecture in reliability block diagrams as well as on a new concept of future-oriented modeling of imaged components with concurrent, finite state machines. For analyzing correct and degraded system states, an algorithm of reliability analysis is applied on the reliability block diagram. In the field of redundancy management for the visualization and analysis of failure injection, failure propagation and reconfiguration, this is an algorithm that based on Depth-First Search.