Abstract: Flight Control Computer Systems(FCCS) of Boeing 777 and Airbus A320 are described from a fault-tolerant standpoint. The FCCS of the new generation of civil airlines exploits dissimilar redundancy technology both in hardware and software in order to tolerate the common-mode failures. But the fault tolerant architectures and the manner in which function are allocated to each computer of this two types of FCCS are different. By using GSPN, the redundant architecture and dynamic behavior of fault-tolerant system of Boeing 777 are described, and the reliability and fault-tolerant capability are evaluated. Some suggestions are offered for analysis and design of the fault-tolerant flight control system of large aircraft of our country.

Key words: flight control computers, dissimilar redundancy, reliability, fault tolerance