777 AIRCRAFT MAINTENANCE MANUAL
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AFDS -FUNCTIONAL DESCRIPTION -PITCH CONTROL
General
The AFDC pitch control laws calculate part of the pitch command signal that goes to the PFC. They also calculate the F/D data.
The AFDC calculates a vertical speed command for these modes:
*
Vertical speed (V/S)
*
Flight path angle (FPA).
The AFDC calculates a speed command for these modes:
*
Takeoff (TO)
*
Go-around (G/A)
*
Flight level change (FLCH).
The AFDC calculates a position command for these modes:
*
Altitude hold
*
Altitude select
*
Glideslope (G/S)
*
Flare.
These commands go to the flight directors (F/D) and the PFCs.
Vertical Speed/Flight Path Angle
The AFDC calculates a vertical speed command.
EFFECTIVITY
BEJ ALL
The AFDC uses these signals to calculate the vertical speed command:
*
MCP selected vertical speed or flight path angle calculated vertical speed
*
Vertical speed.
Speed-Through-Elevator
The speed-through-elevator function supplies protection for:
*
Minimum speed
*
Windshear
*
Maximum speed.
The AFDC uses angle of attack (AOA) and pitch rate to calculate the minimum speed.
The AFDC uses altitude rate and forward gust rate to calculate the windshear.
The AFDC uses these to calculate the maximum speed:
*
Maximum velocity (VMO)
*
Maximum mach (MMO)
*
Flap placard signals.
The AFDC uses selected mach or speed to calculate the speed signal. It also uses engine out during TO calculations.
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AFDS -FUNCTIONAL DESCRIPTION -PITCH CONTROL
The AFDC uses the speed signal with true airspeed to calculate the speed command. The AFDC also makes sure the speed error stays in the protection limits.
Vertical Position
The AFDC uses these to calculate the altitude hold/altitude select position command:
*
MCP selected altitude
*
Baro altitude
*
Altitude rate.
The AFDC uses G/S deviation and G/S deviation rate to calculate the glideslope position command.
The AFDC uses gear altitude and gear altitude rate to calculate the flare position command.
Vertical Navigation (VNAV)
The AIMS cabinet sends VNAV steering commands to the AFDC.
Pitch Flight Director (F/D)
The AFDC uses these to calculate the pitch F/D command:
*
Pitch attitude
*
Turn compensation
*
Pitch command.
The F/D then formats the signal and sends it to AIMS.
Pitch CMD Limit
The AFDC limits the rate and angle of the pitch command signal that goes to the PFCs.
EFFECTIVITY BEJ ALL 22-11-00
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AFDS -FUNCTIONAL DESCRIPTION -PITCH CONTROL
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777 AIRCRAFT MAINTENANCE MANUAL
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AFDS -FUNCTIONAL DESCRIPTION -ROLL AND YAW CONTROL
General
The AFDC roll/yaw control laws calculate the roll and yaw signals that go to the PFC. They also calculate the F/D data.
Lateral Navigation (LNAV)
The AIMS flight management computer function or the control and display units send LNAV steering commands to the AFDC.
Roll Attitude Hold
The AFDC calculates a roll attitude hold command when the pilot engages the autopilot with the bank angle more than 5 degrees, and with no roll mode armed.
Heading/Track
The AFDC calculates a heading/track command for these modes:
*
Heading select
*
Heading hold
*
Track select
*
Track hold.
The AFDC uses these inputs to calculate the roll command:
*
Mode control panel (MCP) bank limit
*
Heading/track select
*
MCP selected heading
*
Airplane heading
EFFECTIVITY
BEJ ALL
*
MCP selected track
*
Ground track.
Localizer
The AFDC calculates localizer commands for approach and localizer modes.
The AFDC uses these inputs to calculate the roll command:
*
Localizer deviation
*
Localizer deviation rate
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本文链接地址：777 AMM 飞机维护手册 自动飞行 Autoflight(22)
