Triple-triple redundant 777 primary flight computer

The flight control system for the Boeing 777 airplane is a Fly-By-Wire (FBW) system. The FBW system must meet extremely high levels of functional integrity and availability. The heart of the FBW concept is the use of triple redundancy for all hardware resources: computing system, airplane electrical power, hydraulic power and communication path. The Primary Flight Computer (PFC) is the central computation element of the FBW system. The triple modular redundancy (TMR) concept also applies to the PFC architectural design. Further, the N-version dissimilarity issue is integrated to the TMR concept. The PFCs consist of three similar channels (of the same part number), and each channel contains three dissimilar computation lanes. The 777 program design is to select the ARINC 629 bus as the communication media for the FBW.