Need for Powered Control System The Complexity and Weight of the system (Mechanical) increased with Size and Performance of the aircraft. When the pilot’s action is not directly sufficient for the control, the main option is a powered system that assists the pilot. The hydraulic system has demonstrated to be a more suitable solution for actuation in terms of reliability, safety, weight per unit power and flexibility, with respect to the electrical system

FCS:POWERED FLYING CONTROLS 2 main types: Power assisted Power operated PURPOSE: In to transonic and near supersonic regime bought deficiencies in mechanical flying control systems also the physical power was inadequate for the task. To move the control surface by hydraulic power in response to the manual operation of the control column or rudder pedals.

FCS:POWERED FLYING CONTROLS Power Assisted

FCS:POWERED FLYING CONTROLS Power Assisted When the pilot moves the control column backward to initiate a climb, the control lever pivots about point ‘X’, and commences moving the elevator UP and at the same time, the control valve pistons in the servo valve of PFCU are displaced and this allows hydraulic fluid under pressure to flow to the left-hand side of the actuating jack piston. The piston rod which is secured to the aircraft’s will be stationary and the reaction of the pressure exerted on the piston causes the whole servo-unit, and control lever, to move to the left.

FCS:POWERED FLYING CONTROLS Power Assisted Pilot will move the control column forward to initiate a climb down tendency, the control lever pivots about point ‘X’, and commences moving the elevator DOWN and at the same time, the control valve pistons in the servo valve of PFCU are displaced This allows hydraulic fluid under pressure to flow to the right-hand side of the actuating jack piston, the piston rod which is secured to the aircraft’s will be stationary and the reaction of the pressure exerted on the piston causes the whole servo-unit, and control lever, to move to the right.

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Disadvantages of Mechanical and Hydro-Mechanical Systems Heavy and require careful routing of flight control cables through the aircraft using pulleys, cranks, tension cables and hydraulic pipes. They require redundant backup to deal with failures, which again increases weight. Limited ability to compensate for changing aerodynamic conditions

FCS:POWERED FLYING CONTROLS Fully powered flight controls PURPOSE : Mechanical input/feed back servo actuator is introduced in this control. This system is irreversible, not permitting any load feed back from the control to the cockpit. Artificial feel is available to the pilot with ‘q’ feel system. A powered flying control unit [PFCU] is a remote position of servo mechanism and servo valve.

FCS:POWERED FLYING CONTROLS Fully powered flight controls SERVO MECHANISM: A type of control system in which a small signal or small force is used to control a much larger force. In a hydraulic servomechanism, a sensor detect that some type of output movement is needed. A control valve directs hydraulic fluid into a hydraulic actuator, and the movement takes place. A feed back sensor compares the amount the actuator moves with the amount of movement the original sensor called for, and when the actuator has moved the correct amount, the selector valve is shut off.

FCS:POWERED FLYING CONTROLS Fully powered flight controls OPERATION: In the neutral position, the servo valve piston assembly closes its ports in the servo valve body, so that the hydraulic fluid is trapped in either side of the ram to lock the controls in the selected position. The fluid in the other end of the ram is directed through other port of servo valve to the return line back to reservoir. Greater the displacement of the cockpit control greater the displacement of the servo valve piston.

FCS:POWERED FLYING CONTROLS Fully powered flight controls OPERATION: A feed back sensor compares the amount the actuator movement with the amount of movement the original sensor called for, and when the actuator has moved the correct amount, the selector valve is shut off.

FCS:POWERED FLYING CONTROLS Fully powered flight controls OPERATION: This system is installed to powered flying control only as the control column is not directly connected to the control surface.