LEFT RIGHT
Spoiler Control System
Figure 17
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MAINTENANCE MANUAL
(2)
Each SCM drives two PCAs, one per spoiler. Feedback from each PCA RVDT provides panel position to the SCMs. The SCMs command spoiler travel proportional to control wheel rotation. Spoiler travel is limited to a 45-degree maximum, which is equal to 85 degrees control wheel rotation.
(3)
All the spoilers are used for lateral control except panels four and nine. These are used as ground speedbrakes only and have a maximum travel of 55 degrees. The remaining spoilers can be used as inflight speedbrakes with varying maximum limits. When the airplane lands, the automatic speedbrake system deploys all panels to the maximum ground limit.
U. Elevator Control System (Fig. 18)
(1)
The elevator control system is operated either manually or by the autopilot. Manual pitch control is obtained with separate cable systems. Control columns on a torque tube move tension regulators, cable, aft quadrants, linkages, PCAs, and elevators. Manual control is unassisted mechanical movement of the PCAs, which then move the elevators. The aft quadrants are aft of the stabilizer. The PCAs are on the stabilizer aft spar.
(2)
AIRPLANES WITH CONTROL WHEEL STEERING; a column force transducer on each control column provides inputs to each FCC. This allows manual control when the autopilot is engaged in control wheel steering (CWS) mode.
(3)
Autopilot input is from three flight control computers (FCCs) to the three Autopilot Pitch Control Servos (APCSs). The servos drive the elevators and back-drive the elevator linkage to move the control columns. The servos contain LVDTs that provide servo and surface position feedback to the FCCs.
(4)
Control inputs are conditioned to provide a sense of feel and centering. Feel is introduced by a feel and centering unit. Inputs are from the neutral shift and a feel computer. The feel computer uses dynamic pressure (CAS) and stabilizer position to vary the feel. The feel unit includes the centering device. Faults are indicated with an ELEV FEEL message on the upper EICAS display unit (Ref 31-41-00).
(5)
Elevator control movements are routed to both left and right power control actuators by mechanical linkage. There is an interconnection between elevator PCA linkages by slave cable to prevent major asymetry. Position transmitters are located at each elevator to provide control surface position on the lower EICAS display unit status page.
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MAINTENANCE MANUAL
ELEVATOR
CONTROL
RUD
CABLE
LEFT SIDE
OVERHEAD CABLES AIL ELEV AIL
RIGHT SIDE EICAS DISPLAY STATUS PAGE
ELEVATOR CONTROL
DUAL AFT
QUADRANT
WITH OVERRIDE
MECHANISM
OVERRIDE
CONTROL
COLUMNS
DUAL FEEL
COMPUTER
CABLE
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