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Each pressure transducer connects to two pressure ports. The ports are symmetrically positioned, one on each side of the vertical stabilizer. Non metallic hoses connect the ports to the pressure transducers. An electrical cable connects to one connector on the differential pressure transducer.
There is about 6 ft (1.83 m) separation between the two pressure transducers and their associated ports.
Location
The gust suppression pressure transducers are near the vertical stabilizer leading edge, on the aft side of the auxiliary spar. The ports are on the composite skin panels of the vertical stabilizer. The pressure transducers are above the pressure ports to permit drainage of moisture from the tubes and the ports.
To get access to each transducer, remove a skin panel of approximately 30 in x 48 in (0.76 m x 1.22 m) on the left side of the vertical fin.

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RUDDER CONTROL -GUST SUPPRESSION PRESSURE TRANSDUCERS

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RUDDER CONTROL -RUDDER PCU -INTRODUCTION

Purpose

Three rudder PCUs move the rudder. Electrical signals from the ACEs command the rudder PCUs. Each rudder PCU operates with hydraulic power from a different hydraulic system.
Location

The rudder PCUs are on the rear spar of the vertical stabilizer. Remove three panels on the left side of the vertical stabilizer to access the PCUs. Each panel is approximately 20 in x 20 in (0.5 m x 0.5 m).
Physical Description

The kick link connects the PCU to the rear spar fitting. The actuator rod and the reaction link connect to the rudder PCU fitting.
Two electrical connectors of different sizes connect to the lower side of the PCU.
Hydraulic tubing connects to ports on the upper side of the PCU.
The right hydraulic system supplies power to the lower rudder PCU, the left hydraulic system to the middle PCU, and the center hydraulic system to the upper PCU.
A rate fuse is on the center hydraulic system supply line to the upper PCU. A check valve is on the return line from the upper PCU to the center system.
Training Information Point
Remove and install the rudder PCU as one assembly with the reaction link. The rudder PCU disconnects from the kick link which stays on the airplane.
Install a hoist swivel fitting to the hoist attach point of the PCU. Use a ground support equipment (GSE) hoist to support the PCU during removal and installation.
After installation of the rudder PCU, the actuator null LVDT requires adjustment. Remove the null LVDT access cover to adjust the null LVDT.
Put the nose gear steering tow lever in the tow position before you move the rudder pedals to operate the rudder system.

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RUDDER CONTROL -RUDDER PCU -INTRODUCTION

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777 AIRCRAFT MAINTENANCE MANUAL

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RUDDER CONTROL -RUDDER PCU -PHYSICAL DESCRIPTION

Physical Description

All three rudder PCUs are identical. Each rudder PCU, with its reaction link, weighs approximately 98 lb (44.5 kg).
The rudder PCU contains a hydraulic actuator with a control module. The control module contains:
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An electrohydraulic servo valve (EHSV)

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A pressure reducer solenoid valve

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A bypass solenoid valve

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A damped solenoid valve

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A mode selector valve

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A differential pressure sensor

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Two bypass check valves

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Two relief valves

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A thermal relief valve

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A compensator/relief valve

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Two anti-cavitation check valves

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An inlet check valve

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An inlet filter.

Hydraulic Actuator

The actuator piston has an LVDT that sends actuator position feedback signals to the ACE. The actuator piston also has a null LVDT to adjust the null position of the actuator piston LVDT during installation of the PCU.
EHSV
The EHSV controls the hydraulic power to the extend and retract sides of the actuator. The EHSV has an LVDT that sends EHSV position feedback signals to the ACE.
Pressure Reducer Solenoid Valve
The pressure reducer solenoid valve commands the pressure reducer valve to decrease the hydraulic pressure to 1910 psi. Reduced pressure on the actuator decreases the probability of leak and fatigue loads during normal operation.
　
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