Fly-by-Wire (FBW) Flight Control System

The earliest aircraft were controlled by the pilot using the steel cables, pulleys and hydraulic actuators. The use of these pulleys, cranks, tension cables and hydraulic pipes adds much weight to the aircraft and it requires careful routing and maintenance work. To eliminate and reduce this problem, a new system called Fly-by-Wire (FBW) flight control system came into existence in late 1970’s using the analog implementation while digital FBW systems have been in service since the late 1980’s. The introduction of fly-by-wire (FBW) flight control system has been a watershed development in aircraft evolution as it has enabled technical advances to be made which weren’t possible before.

As the name implies, FBW system is flying the aircraft by wires because all commands and signals are transmitted electrically along wires. Fly-by-Wire technology is simply replacing mechanical equipment with the electronic wires connected to the hydraulic actuators to move the aircraft control surfaces for the preferred movement of the aircraft. Here, the response from the pilot control is converted into electrical signals which travel to the main flight computer, from there to the actuator control electronics and to the control surfaces from actuator, all through the series of cables and wires. Fly-by-Wire control system also allows aircraft computers to perform task without pilot input. Gyroscope and air data sensors mounted in an aircraft sense the various movement changes like the pitch, roll and yaw. Any change in these movements sends signals to the computer which automatically moves the control surfaces to stabilize the aircraft. The system runs onboard electrical power source generated by the turbines of the aircraft engine.

Fly-by-Wire (FBW) system is the safer, more reliable and more responsive way of aircraft control. Introduction of this system in the aircraft helps to reduce the aircraft weight and maintenance work due to the elimination of heavy cables and pulleys. FBW system insures quick, smooth and fast response to the pilot’s commands. FBW system is safer than the conventional system as any change in motion of the aircraft is immediately sensed by the motion sensors and causes the computers to move the appropriate control surfaces so as to apply forces and moments to the aircraft to correct the deviation from the commanded flight path. FBW system enables a smaller tailplane, fin and rudder to be used, thereby reducing both aircraft weight and drag, active control of the tailplane and rudder making up for the reduction in natural stability. As FBW system can control the aircraft without the pilot input, it greatly eases the autopilot integration task and helps in aircraft maneuvering.

FBW system is run by the electrical power, so the major con of FBW system is the loss of electrical power. That’s why there are redundant systems in new design to try and eliminate that kind of failure. FBW system is a computerized system consisting lots of wires and cables, so a slight malfunction in these wires or cables may cause the system failure. Also this system is a more complex and expensive than the earlier conventional system.

Fly-by-Wire (FBW) system is extremely safe and reliable technology in controlling the flight control surfaces of the aircraft. Almost every modern aircrafts and airliners have adapted this technology including the big names like Airbus and Boeing. This technology accounts as one of the greatest breakthrough in the aviation field and is in the phase of continue developing. Let us hope to see more discoveries in the field of Fly-by-Wire (FBW) system so that people can fly more safely, conveniently and economically in the future than today.