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The left and right aileron commands go to the ACEs and then from the ACEs to the EHSV of each aileron PCU. The lockout command also goes to the ACEs, then to the blocking solenoid of each aileron PCU.
Flaperon Bypass Logic
The flaperon bypass logic gets signals from the left and right engine running status and the position of the left and right thrust resolver angles. The logic also gets the CAS signal from the ADIRU and the air/ground signal from the WOW cards.
The logic operates on the ground with at least one engine running and its thrust resolver angle near the takeoff position. With the airspeed less than 85 knots, the logic sends a command signal to all four ACEs to put the flaperon PCUs in bypass mode. This decreases the flaperon actuator fatigue cycles caused by the engine exhaust on the flaperons.
At low airspeed with the flaperon PCUs in bypass mode, the weight of the flaperon may cause the flaperons to move down to the PCU stops. The exhaust flow of the engines may cause the flaperons to flutter. As the airspeed increases during takeoff roll, the airloads may cause the flaperons to float to the neutral position.
EFFECTIVITY BEJ ALL
When the airspeed is approximately 100 knots, the logic stops operation and sends a command signal to the ACEs to put the flaperon PCUs in the normal mode. The flaperon PCUs then gradually move the flaperons to the commanded position.
The flaperon bypass logic is inhibited for 30 seconds after an air to ground transition. This prevents the flaperon PCUs to be in bypass during touch and go operation of the airplane.
Landing Attitude Modification
The landing attitude modification (LAM) logic decreases the flaperon droop when the airplane is in an overspeed approach with flaps at the 25-unit or 30-unit position. The PFC calculates the reduction of flaperon droop proportionally to the overspeed increment. Full flaperon droop removal occurs when the airspeed is 20 knots more than the approach landing speed shown in the airplane flight manual.
When the LAM logic is active, it reduces wing lift and causes an increase in angle-of-attack. This increases the nose gear ground clearance.
Flaperon Force Fight Equalization
The PFCs use flaperon PCU differential pressure data from the ACEs to adjust all the flaperon PCU commands to decrease PCU force fight. The PFCs send these adjusted commands to the ACEs and the EHSV of each flaperon PCU.
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Bank Angle Protection
The BAP function supplies a control wheel force cue to the pilot when the bank angle is more than 35 degrees. The PFCs use flight data from the ADIRU and signals from the wheel force transducer to calculate backdrive actuator commands which go to the AFDCs. This causes the backdrive actuators to apply a force on the control wheels which increases as the bank angle increases more than 35 degrees.
When the BAP function is active, the ELMS prevents the operation of the aileron trim.
Autopilot Roll Commands
During autopilot operation, the PFCs use the autopilot roll commands to calculate the aileron and flaperon commands. They also calculate the backdrive actuator commands which go to the AFDCs. This causes the backdrive actuators to move the control wheels in the same relationship to the autopilot commands. When the pilots move the control wheels while the autopilot is engaged, the autopilot disengages. The backdrive actuators then disengage and stop movement of the control wheels.
When the autopilot is engaged, the ELMS prevents the operation of the aileron trim.
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General
In secondary mode operation of the PFCS, the PFCs calculate roll control commands based on: 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 1(42)
