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ELEVATOR CONTROL -ELEVATOR FEEL -FUNCTIONAL DESCRIPTION
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ELEVATOR CONTROL -COLUMN POSITION TRANSDUCERS
Purpose
The six column position transducers measure the position of the control columns. The transducers send analog electrical signals to the ACEs.
Physical Description
Each position transducer is an LVDT. The ACEs supply 7v ac, 1800 Hz excitation power.
The aft attach point on each position transducer connects to a fixed point on the elevator feel unit. The forward end attaches to a transducer crank.
Each transducer crank attaches to its shaft assembly with a spline. The spline has a missing tooth to help locate the crank on the shaft. Each transducer crank has two shear rivets to allow override of a jammed position transducer.
Each transducer has an electrical cable which connects to the ACE connector bracket. This bracket has three receptacles, one for each position transducer. The order in which each position transducer connects to the connector bracket determines the transducer-to-ACE relationship.
Location
Three column position transducers are on each elevator feel unit.
Functional Description
When the splined input shaft rotates in response to control column movement, the column position transducers extend or retract. Each position transducer sends an analog electrical signal to one ACE.
Indications
On the status display, the message CONTROL COLUMN XDCR shows that there is a failure in one of six column transducers.
The status message FLIGHT CONTROL SYS shows when two or more column position transducers are failed.
Training Information Point
The six column position transducers are identical to the six wheel position transducers and the four pedal position transducers. There are 17 of these identical position transducers on the airplane.
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ELEVATOR CONTROL -COLUMN BREAKOUT MECHANISM
Purpose
The column breakout mechanism makes it possible to control the elevators if a jam occurs in a control column, the column torque tubes, or an elevator feel unit.
Physical Description
The column breakout mechanism has a cam on the right torque tube. The cam follower assembly roller is on the left torque tube. Two springs keep the roller on the cam. The two torque tubes have connections for the elevator feel unit and backdrive actuator rods.
Location
The breakout mechanism is under the flight deck, aft of the column torque tubes. Access is through the forward equipment center door.
Functional Description
During normal operation, the two torque tubes of the column breakout mechanism are held together by the springs of the cam and roller mechanism. This supplies a load path to transfer control column force from one side to the other. During normal operations, movement of one control column will cause approximately the same movement of the other column.
If a jam occurs in the elevator control mechanism on either pilot’s side, the other side will be free to move. The roller then moves out of the cam detent which allows control column movement on the side opposite the jam.
A force at the control column of approximately 50 lb (23 kg) is necessary to move the roller out of the detent position.
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ELEVATOR CONTROL -ELEVATOR PCU -INTRODUCTION
Purpose
The elevator PCUs move the elevators. Electrical signals from the ACEs command the elevator PCUs. Each elevator has two PCUs.
Location
The two PCUs are side by side on the rear spar of the horizontal stabilizer. To get access to each PCU, remove a 24 by 24 inch (Approx.) panel on the bottom of the stabilizer.
The kick link connects the PCU to the rear spar fitting. The actuator rod and the reaction link connect to the elevator structure at the PCU fitting.
Two electrical connectors of different sizes connect to the upper side of the PCU.
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本文链接地址：777 AMM 飞机维护手册 飞行操纵 Flight Controls 2(6)
