The two LVDTs of the wheel force transducer send signals to the L2 ACE and the C ACE. The ACEs transmit these signals to their on-side PFCs.
Aileron PCUs
Each ACE sends output command signals to the two PCUs of the same aileron. Two output command signals go to the EHSV and the bypass solenoid of one PCU on the assigned aileron. Another output command signal goes to the blocking solenoid of the adjacent PCU on the same aileron. The PCU sends feedback signals to its assigned ACE from:
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The EHSV position LVDT
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The actuator piston position LVDT
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The actuator null LVDT.
Flaperon PCUs
Each ACE sends output command signals to one flaperon PCU. The output command signals go to the EHSV and the bypass solenoid. The PCU sends feedback signals to its assigned ACE from:
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The EHSV position LVDT
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The differential pressure LVDT
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The actuator piston position LVDT
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The actuator null LVDT.
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AILERON AND FLAPERON CONTROL -FUNCTIONAL DESCRIPTION
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AILERON AND FLAPERON CONTROL -FUNCTIONAL DESCRIPTION -ACE SERVO LOOP
General
The ACE contains a servo loop circuit to produce the command signals for the PCUs.
In normal and secondary mode, the PFC sends the command signals to the ACE. In direct mode the ACE calculates the command signals.
Servo Loop Operation
The ACEs use the aileron and flaperon command signals through a servo loop. The command signals then go to the EHSV of the PCUs. The ACEs also use the command signals to monitor for failures.
The movement of the EHSV sends hydraulic pressure to extend or retract the actuator.
The EHSV LVDT measures the movement of the EHSV and supplies a feedback signal to the ACEs. The ACEs use this feedback signal in the failure monitor.
The actuator position LVDT measures the movement of the actuator and supplies a feedback signal to the ACEs through the actuator null LVDT.
The actuator null LVDT is in series with the actuator position LVDT. The actuator null LVDT modifies the signal from the actuator position LVDT.
The actuator position LVDT supplies a feedback signal to the ACEs to close the servo loop. The ACEs use this feedback signal to monitor for failure. The signal also goes to the PFC.
On the flaperon PCUs only, a differential pressure LVDT measures the differential pressure across the actuator piston. The signal from the differential pressure LVDT goes to the ACEs for the servo loop. The signal also goes to the PFCs for force fight equalization.
Failure Monitor
The ACE has a failure monitor to do a check of the correct operation of the PCU. The monitor uses the ACE command signal and the feedback signals from the EHSV LVDT and the actuator LVDT. When the failure monitor finds a fault with the PCU or the ACE, it de-energizes the bypass solenoid of the PCU.
Training Information Point
After installation of the aileron or the flaperon PCU, you do a MAT test and adjust the actuator null LVDT to have the control surface at the rig position.
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AILERON AND FLAPERON CONTROL -FUNCTIONAL DESCRIPTION -ACE SERVO LOOP
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AILERON AND FLAPERON CONTROL -FUNCTIONAL DESCRIPTION -NORMAL MODE
General
In normal mode operation of the PFCS, the PFCs calculate roll control commands based on:
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Aileron schedule
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Flaperon schedule
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Aileron and flaperon droop logic
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Aileron lockout logic
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Flaperon bypass logic
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Landing attitude modification
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Flaperon force fight equalization
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Failure monitor
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Bank angle protection (BAP)
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Autopilot roll commands.
Aileron and Flaperon Schedules
The PFCs receive roll control command signals from the wheel position transducers and from the autopilot. The aileron and flaperon schedules calculate aileron and flaperon input commands. The PFCs invert the commands for the left wing in relation to the commands for the right wing.
The aileron schedule has limits that vary as a function of the flap position data from the FSEU and the airspeed data from the ADIRU. When the flaps are in positions 5 through 30, and the airspeed is more than 65 knots, the PFC limits the aileron trailing edge down movement to 8 degrees. When the airspeed is less than 65 knots, the PFC commands let the aileron move to its maximum trailing edge down position. This lets the pilots to do a full authority check during preflight.
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