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MAINTENANCE MANUAL
RUDDER
Rudder Structure
Figure 10
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MAINTENANCE MANUAL
T. Rudder Trim Control Switch and Indicator (Fig. 11)
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(1)
The rudder trim switch is located on aft electronic control panel P8 and activates arming and control switches which direct electrical input to the rudder trim actuator motor. The switch is spring-loaded to return to neutral. The RUD TRIM circuit breaker is located on overhead circuit breaker panel P11 and receives 28 volts dc from the dc standby bus.
(2)
The trim position indicator is driven electrically by a transmitter in the rudder trim actuator on the feel, centering and trim mechanism. The indicator shows up to 17 units of left or right trim. The indicator is located on P8 next to the rudder trim knob and is powered by 28 volts ac from left bus. The RUDDER TRIM POS circuit breaker is located on P11.
TRIM INDICATOR
RUDDER TRIM SWITCH
AILERON/RUDDER TRIM CONTROL
MODULE, M74 (P8 PANEL)
Rudder Trim Control and Indication
Figure 11
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MAINTENANCE MANUAL
3. Operation
_________
A. Functional Description (Fig. 12)
______________________
(1) Pedal Adjustment
________________
(a)
Pedal adjustment cranks drive the adjustable yokes through a flexible cable. Rotation of the crank causes rotation of a jackshaft which moves the yoke forward or aft. Control rods attached between the rudder pedals and yokes move the pedals in the direction of yoke movement, adjusting the closeness to the pilot.
(2)
Rudder Pedal Steering Interconnect Mechanism
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(a)
The rudder pedal linkage is connected to the steering cables through an interconnect mechanism. The rudder pedal steering interconnect mechanism is located below the flight compartment door under the captain's side console. It is used to engage or disengage rudder input into the nose wheel steering system. Cable motion for driving the rudder pedal interconnect mechanism is provided by strut mounted piston linkage. Rudder pedal steering is engaged depending on nose landing gear oleo position.
(3)
Pedal Input to Feel, Centering and Trim Mechanism
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(a)
Each set of pedals drives its forward quadrant through two control rods. Pushing on one pedal causes its forward quadrant to rotate. The forward quadrants are tied together by a nonadjustable bus rod. Pedal input causes the forward quadrants to rotate in opposite directions, which backdrives the other set of pedals and rotates the aft quadrant.
(4)
Rudder Feel, Centering and Trim Mechanism
_________________________________________
(a)
Flight crew inputs through the rudder pedals and inputs from the autopilot servos provide a rotational force to the offset torque tube of the feel, centering and trim mechanism. A cam plate mounted on the torque tube also rotates, forcing a roller to ride up the inclined cam face. As the roller rides up the cam, it causes the spring arms to spread, causing the tension spring to stretch. As a result, the spring load increases and when the input is removed, this load drives the cam plate back to the detent position. This back drives the pedals to the centered or trimmed position.
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