Maintenance planning for fault tolerant designs used in critical applications

In the last few years, digital systems, especially computers, have been incorporated into commercial and military aircraft flight control systems, and industrial controllers. A system used in a typical critical application is the architecture of the X-29 aircraft flight control system, based on triple modular redundancy. The control system uses three identical computers performing the same operations. The results from each computer are examined and the output from the system is formed via a majority vote of the three results. For such a system, used in critical applications, it is extremely important, besides other evaluations, to plan the maintenance logistic support, knowing the failure rates and cost of all its blocks, the system quantity and installation sites, possible stock and spare source locations, etc