All modern aircraft flight control systems are literally 'fly-by-computer' systems. The flight management computer (FMC) receives the command signal from position sensors mounted in the control column, pedals and thrust levers to electro-mechanically actuate the movement of the flight control surfaces (ailerons, elevators, rudder) and the power to the engines. An aircrafts electro-hydraulic control system consists of control electronics (command signal), a servo-amplifier, a servo-valve, an electro-hydraulic actuator and a feedback sensor, which measures the position of the actuator. These position sensors are usually high specification contactless LVDT (Linear Variable Differential Transformer) or RVDT (Rotary Variable Differential Transformer) types. Contactless LVDT and RVDT sensors are chosen due to their 'long operational life' and high reliability in extreme operating conditions. Virtually all 'fly-by-wire' systems have built in redundancy, duplex or quadruplex systems (multi-channel), which mean that each control function will have up to four sensors and control wires. If the signal is lost from one or two sensors, the others will continue working on a separate electrical system.

A benefit of fly-by-wire systems for military aircraft is improved manoeuvrability and flight performance. The system also improves combat survivability as damage to hydraulic systems causes leaks that can lead to loss of aircraft control. Electrical wires can be more flexibly routed compared to hydraulic lines and are less susceptible to damage. The 'on-board' aircraft computer also offers flight envelope protection, which prevents the aircraft from exceeding pre-set limits such as stall or spin. A fly-by-wire system also improves flight economy through weight reduction, by the elimination of some of the heavy mechanical components.

Active Sensors design and manufacture LVDT and RVDT sensors for primary and secondary flight control electro-hydraulic actuators, engine control valves, brake-by-wire systems and much more... We meet customers system development needs by offering a complete sensor design and delivery service for fixed and rotary wing aircraft.

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