RUDDER CONTROL -RUDDER PCU -FUNCTIONAL DESCRIPTION -PCU MODES

EFFECTIVITY BEJ ALL  27-21-00 
Page 53 
D633W101-BEJ  Jan 05/2002 

RUDDER CONTROL -RUDDER ASSEMBLY

Purpose

The rudder supplies control of the airplane in the yaw direction. The rudder tab pivots on the lower trailing edge of the rudder.
Physical Description

The rudder is a light weight composite material structure. The skin is reinforced graphite/epoxy bonded to a core of Nomex honeycomb. The overall dimensions are approximately 98 in by 442 in (2.5 m by 11.2 m). The rudder weighs approximately 577 lb (262 kg).
A counterbalance at the tip of the rudder prevents flutter.

The rudder attaches to the vertical stabilizer with 10 hinges. Three PCUs attach to the rudder and move it. Jumpers and static dischargers supply electrostatic protection to airplane systems.
Functional Description

The rudder PCUs have internal stops that limit the rudder surface deflection. The rudder has a maximum movement of 27 degrees in both directions at low airspeed under no load conditions.
Under loads, the maximum PFCs and ACEs command signals move the rudder to a nominal position of 25 degrees in both direction at low air speed.
Training Information Point
Two hoist attach points are on the rudder. They are near the top and bottom rudder hinges. Remove a small hinge line seal panel to get access to the hoist attach points.

EFFECTIVITY BEJ ALL  27-21-00 
Page 54 
D633W101-BEJ  Sep 05/2002 

777 AIRCRAFT MAINTENANCE MANUAL

RUDDER CONTROL -RUDDER ASSEMBLY

EFFECTIVITY BEJ ALL  27-21-00 
Page 55 
D633W101-BEJ  Jan 05/2002 

RUDDER CONTROL -RUDDER TAB ASSEMBLY

Purpose

The rudder tab pivots on the lower trailing edge of the rudder. It moves in the same direction of the rudder to increase its effect.
Physical Description

The rudder tab is a light weight composite material structure. The skin is reinforced graphite/epoxy bonded to a core of Nomex honeycomb. The overall dimensions are approximately 50 in by 128 in (1.3 m by 3.2 m). The rudder tab weighs approximately 110 lb (50 kg).
The rudder tab attaches to the rudder by 5 hinges. Three adjustable control rods command the movement of the rudder tab based on the rudder movement. Three fairings cover the control rod connections to the rudder tab.
The rudder index plate, on the upper skin of the tail cone, shows the position of the rudder tab in relation to the airplane centerline.
Functional Description

The rudder tab has a maximum movement of 27 degrees in both directions in relation to the rudder. For each degree of movement of the rudder, the rudder tab also moves one degree.
At full movement of the rudder (27 degrees), the rudder tab moves 27 degrees in relation to the rudder. This results in a 54 degree tab movement in relation to the centerline of the airplane.
Training Information Point
Two hoist attach points are on the rudder tab. They are near the top and bottom tab hinges. Remove a small hinge line seal panel and one fairing to get access to the hoist attach points.
When the airplane is on the ground with the rudder at center, the rudder tab control rods deflect the rudder tab to the left ofthe airplane centerline. This deflection is necessary for thermal expansion of the rudder tab control rods.

EFFECTIVITY BEJ ALL  27-21-00 
Page 56 
D633W101-BEJ  Sep 05/2002 

777 AIRCRAFT MAINTENANCE MANUAL

RUDDER CONTROL -RUDDER TAB ASSEMBLY

EFFECTIVITY BEJ ALL  27-21-00 
Page 57 
D633W101-BEJ  Jan 05/2002 

RUDDER CONTROL -FUNCTIONAL DESCRIPTION

General

The rudder control system uses input command signals from the rudder pedal position transducers.
The ACEs receive the input signals and transmit them to the PFCs. The ACEs supply output command signals to the rudder PCUs.
Rudder Pedal Position Transducers

Each ACE receives the signals from one rudder pedal position transducer. The L1 ACE and C ACE receive signals from the rudder pedal position transducers on the left shaft assembly. The L2 ACE and the R ACE receive signals from the rudder pedal position transducers on the right shaft assembly. After they change the signals to digital format, the ACEs send these signals to the PFCs through the flight controls ARINC 629 buses.
Each PFC receives input signals from all four rudder pedal position transducers. The PFC selects by mid-value selection and averaging which signal to process.
Gust Suppression Pressure Transducers
　
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