757 Fly-By-Wire Demonstrator Flight Test

The Boeing Company modified a production 757-200 to emulate the 777 fly-by-wire control laws in order to evaluate the operation and performance of the 777 FBW flight control laws in flight. Following installation and checkout of the FBW system, testing began in March, 1992. Flight testing is currently planned to continue through August, 1992. The conventional 757 longitudinal flight control system is retained but controlled by only the captain’s column. The fly-by-wire system is evaluated by the pilot in the first officer’s seat and the safety pilot function is conducted from the captain’s seat. The flight test FBW longitudinal system is a 2-channel flight control system. The first officer’s column drives the current 757 left and right flight control computers (autopilots) which are modified to act as FBW computers. These FBW computers, which emulate the 777-200 FBW control laws, drive their respective autopilot actuators to control the airplane pitch axis. Directional FBW control laws arc emulated in the existing 757 yaw dampers, with corresponding modifications to the normal 757 directional control system. This paper presents a summary of the airplane FBW modifications and the flight test program to evaluate/validate the 777 FBW flight control laws.