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HORIZONTAL STABILIZER CONTROL -AFT STABILIZER QUADRANT ASSY -TRAVEL LIMIT DRUM ASSEMBLY
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HORIZONTAL STABILIZER CONTROL -CUTOUT SWITCHES
Purpose
The two stabilizer cutout switches stop the stabilizer movement when they are in the CUTOUT position. The pilots use these switches in the unlikely event there is uncommanded stabilizer movement. You can move the switches to the CUTOUT position separately to control either the center or right STCM shutoff valves. These valves control hydraulic power to the stabilizer motors and brakes.
Physical Description
The cutout switches are two toggle switches, each guarded with a safety cover. To move the switches to the CUTOUT position, the pilot must raise the safety guards. The guards move the switches back to the NORM position when they are closed.
Location
The switches are on the aft, left hand side of the P10 control stand.
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HORIZONTAL STABILIZER CONTROL -CUTOUT SWITCHES
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HORIZONTAL STABILIZER CONTROL -STCM -INTRODUCTION
Purpose
There are two stabilizer trim control modules. Each module controls hydraulic pressure to a hydraulic motor and brake. The STCMs receive electrical signal commands from the ACEs and mechanical commands from the alternate pitch trim levers.
Location
The two STCMs are near the ceiling of the stabilizer compartment just aft of the pressure bulkhead. Access to the compartment is by a hatch on the lower left side of the empennage.
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HORIZONTAL STABILIZER CONTROL -STCM -INTRODUCTION
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777 AIRCRAFT MAINTENANCE MANUAL
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HORIZONTAL STABILIZER CONTROL -STCM -PHYSICAL DESCRIPTION
General
The two STCMs are on the airplane structure. Between the STCMs is the control module. Control rods transfer movement in the control module to the STCMs.
Electrical connectors of different sizes connect to the STCMs.
Hydraulic tubing connects to STCM input and output ports.
The center hydraulic system supplies power to the center STCM (located on the left side). The right hydraulic system supplies power to the right STCM.
The two STCMs are identical. Each STCM weighs approximately 29 lb (13 kg).
Each STCM contains an arming and control valve which controls hydraulic power to the hydraulic motor and brake. Movement of the two valves allows hydraulic pressure to release the hydraulic brake and to drive the motor in the commanded direction.
These components control the operation of the STCM:
*
Motor operated shutoff valve
*
Nose down control solenoid
*
Nose down arm solenoid
*
Arm input crank
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Rate control solenoid
*
Nose up arm solenoid
*
Nose up control solenoid
*
Pressure switch
*
Control input crank
*
Brake bypass valve.
Motor Operated Shutoff Valve
The motor operated shutoff valve controls hydraulic power to the STCM. The cutout switches on the control stand, and the ACEs control power to the electric motor of the shutoff valve.
The motor operated shutoff valve has a manual override lever which is also a position indicator.
Nose Up and Nose Down, Arm and Control Solenoids
The ACEs control the nose up and nose down, arm and control solenoids. These solenoids operate valves which control hydraulic pilot pressure to move the arming and control valves.
Arm and Control Input Cranks
The arm and control input cranks connect to an arm and control manual valve in the STCM. The manual valves control hydraulic pilot pressure to move the arming and control valves.
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HORIZONTAL STABILIZER CONTROL -STCM -PHYSICAL DESCRIPTION
Rate Control Solenoid
The ACEs control the trim rate solenoid. The solenoid operates a two position valve. It allows either full or restricted hydraulic flow to the hydraulic motor. This controls the rotation speed of the motor. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：777 AMM 飞机维护手册 飞行操纵 Flight Controls 2(18)
