Fault Analysis of a Distributed Flight Control System

This paper presents how state consistency among distributed control nodes is maintained in the presence of faults. We analyze a fault tolerant semi-synchronous architecture concept of a Distributed Flight Control System (DFCS). This architecture has been shown robust against transient faults of continuous signals through inherent replica consistency. This approach necessitates neither atomic broadcast nor replica determinism. Here, we extend the analysis of replica consistency property to confirm robustness against transient faults in discrete signals in presence of a single permanent fault in a control node. The paper is based on a case study on JAS 39 Gripen, a modern fourth generation multi purpose combat aircraft, presently operating with a centralized FCS. Our goal is to design the DFCS fault management mechanisms so that the distributed treatment of faults corresponds to the existing non-distributed FCS. In particular, fault management mechanisms not existing in the present centralized system but only in the distributed system are considered.