Future aircraft system procurements are expected to utilise a new form of modular architecture. However, the architectures being put forward only provide for hardware partitioning, and there is little protection for safety-critical processes from interference by rogue processes. This paper puts forward a mixed static/dynamic analysis approach for assuring software partitioning of processes within a single hardware partition. Such an approach is a necessity in cost effective modular architectures if all processes are not to be classified and developed as safety-critical.