C. Trim input to the mechanism is provided by a trim actuator attached to adjacent structure. The actuator consists of an electric motor and jackscrew which provides linear motion of the output shaft. The actuator is controlled by switches on the pilots' control stand (Fig. 2). The actuator output shaft is connected to the mechanism support assembly. Output of the actuator repositions the entire trim and feel mechanism, including the input quadrant, to establish a new control system neutral position. This rotation provides an input to the CLCPs which position the lateral flight control surfaces to give the desired trim correction. Rotation of the input quadrant due to trim input also repositions the aileron control wheels away from the normal neutral positions. Positioning of the trim actuator is not affected by reverse forces resulting from normal control of the system.
D. Command from the autopilot module to the mechanism is provided by a lateral autopilot servo (LAS) attached to adjecent structure. The LAS functions in response to roll command signals received from channel C autopilot (AMM 22-13-00/001). The signals cause motion of the LAS output rod. The rod is connected to the mechanism input crank which is attached to the left body input quadrant.
5. Central Lateral Control Packages
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A. Two central lateral control packages (CLCPs), mechanically connected, receive the lateral control input and provide a hydraulically powered output which operates the aileron programmers and spoiler differentials. The CLCP-right autopilot is in the left wheel well. The left CLCP (left autopilot) is in the right wheel well. Hydraulic pressure of 3000 psi is provided to the right CLCP (right autopilot) from main hydraulic supply systems No. 1 and 2. Hydraulic supply systems No. 3 and 4 provide power for the left CLCP (left autopilot). The CLCPs also include provisions for input from the airplane autopilot system (AMM 22-10-00/001).
B. The mechanical input to each CLCP is received by an input lever and is transmitted through dual load path cranks to primary and secondary summing beams. The primary summing beam is connected directly to the spool of the main control valve. The valve is a dual tandem valve with the valve sleeve connected to the secondary summing lever. Lost motion is provided at the connection allowing the sleeve to be repositioned only after a spool motion of 50% of total travel. During normal operating conditions, the sleeve is rarely repositioned. Motion of the valve spool or sleeve ports hydraulic fluid from both supplying systems to a tandem actuator. Motion of the actuator provides the input to the spoiler differential and aileron programmer. The summing beams, connected to the actuator, provide the follow-up to close the control valve when the actuator reaches the desired position.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL
C. Hydraulic fluid to the main control valve and autopilot components passes through replaceable filters. Four anticavitation check valves in the package connect the pressure and return lines. The valves permit hydraulic fluid to flow from a return line to a pressure line to prevent a hydraulic lock which would occur if one hydraulic supply system was shut off.
D. Autopilot components within the CLCP include two solenoid valves, an electrohydraulic servo valve, an autopilot pressure regulator valve, an autopilot actuator and two linear transducers. During manual operation by the aileron control wheels, the solenoid valves are de-energized. The autopilot actuator is not clamped to the intermediate crank and so allows free movement of the summing beams. When the autopilot system is engaged, the solenoid valves energize and allow hydraulic fluid to clamp the autopilot actuator to the output actuator through the summing beams. Autopilot operation is accomplished by electrical signals applied to the transfer valve (electrohydraulic servo valve) which controls the flow of hydraulic fluid to the autopilot actuator. Movement of the autopilot actuator positions the main control valve through the summing beams. Thereafter, functioning is identical, irrespective of the mode of operation (manual or autopilot). The feedback signal to the main control valve is provided by movement of the tandem actuator transmitted through the summing beams. Autopilot feedback signals are provided by linear transducers positioned by the autopilot actuator and the tandem actuator.
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本文链接地址：747-400 AMM 飞机维护手册 飞行操纵 FLIGHT CONTROLS 1(47)
