2001 - 2OO2 TERMS: Aftermarket: Electrohydrostatic actuation (EHA): Swashplate assembly: Primary flight controls: Six degrees of freedom: Digital interface valve: Thrust vector control: Secondary flight controls: Electrohydraulic Servocontrol Actuation: In 2001, Moog began providing a glossary of selected terms relevant to our technology and markets. This year weGLYPH<213>re providing several new terms in the same in-depth fashion as well as abbreviated definitions from the prior years. Spares, repairs, and overhaul of original equipment hardware. Flight-critical controls including ailerons, elevators,  and rudders.  New technology eliminating hydraulic connections and providing electrical power directly to the actuators. Provides adjustability of the angle of any of the rotor blades  simultaneously, allowing the craft to gain or lose altitude, or control attitude. Defines six motions: vertical, lateral, longitudinal,  pitch, roll, and yaw. Supplemental controls that refine an aircraftGLYPH<213>s  performance including trim tabs, wingflaps,  spoilers, speed brakes, and slats. Steering launch vehicles and satellites by directing  the thrust of their rocket engines and booster nozzles. Also used in high performance fighter aircraft. An Industrial servovalve with an embedded digital micro- processor enabling users to define dynamic performance. Servovalve Piston Feedback Transducer This cutaway of an actuator shows the piston which moves inside the cylinder in response to the pressure and flow control of the  servovalve. The piston extends and retracts, providing the motion or force commanded by the computer. 22 Command  Input Signal  (+) Feedback Signal  (—) Actuating Signal Output Feedback Transducer Hydraulic Power Supply Control Computer Actuator Servovalve Servoamplifier 2OO1 2OO2 2OO3 GL0SSARY 0F TERMS M00G TECHN0L0GY m An electrohydraulic servocontrol system consists of six  elements indicated in the diagram below: control electronics which may be a computer, microprocessor or guidance system and which create a command input signal; a servoamplifier which provides a low power electrical actuating signal which is the difference between the command input signal and the feedback signal  generated by the feedback transducer; a servovalve which responds to this low power electrical signal and controls the high power flow of hydraulic fluid to an actuation element such as a piston and  cylinder which positions the device being controlled; and a power supply, generally an electric motor and pump, which provides the flow of hydraulic fluid under high pressure. The feedback  transducer measures the output of the system and converts this measurement into a proportional signal which is sent to the  servoamplifier. The concepts are similar in electromechanical  systems wherein an electric drive and ballscrew are used instead of