Incremental avionics upgrades for legacy aircraft

An affordable and practical methodology to performing legacy aircraft upgrades has been shown using open systems and incremental concepts. This methodology can be applied to the diverse architectures and technologies in legacy aircraft, both to implement new requirements, to replace obsolete parts and to apply required technology. It can be applied at several different levels including components, SRUs, LRUs or systems, depending on what changes are required. The replacement of obsolete military standard parts is rapidly becoming a major issue. However, the replacement of obsolete commercial parts is in many ways even more of a problem because they become obsolete much faster. The incremental upgrade methodology outlined in this paper provides an affordable and practical approach to solving this problem. The key is that the interfaces must be defined and rigorously adhered to so that changes do not ripple to otherwise unaffected parts of the system