777 AIRCRAFT MAINTENANCE MANUAL
TMCS -A/T OPERATION -VNAV DESCENT
EFFECTIVITY BEJ ALL 22-31-00
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TMCS -A/T OPERATION -FLIGHT LEVEL CHANGE
Mode Selection
The TMCF sends A/T servo motor (ASM) commands to control engine thrust when all these conditions are present:
*
A/T arm switches are on
*
An autopilot (A/P) or flight director (F/D) switch is active
*
Flight level change (FLCH) switch is active
*
Airplane is in the air.
Operation
When you push the FLCH mode switch on the MCP, the airspeed window unblanks to show current airspeed. The TMCF uses the difference between the present altitude and the MCP altitude to calculate a vertical speed to capture the MCP altitude. Airspeed does not change. The A/T control laws command thrust which produces a vertical speed to complete the altitude change in 125 seconds. The A/T command can not exceed the thrust limit mode.
If an override occurs while in the FLCH mode, the A/T mode goes to HOLD. HOLD shows on the PFD. The thrust limit mode changes to CLB on the engine primary format. An override occurs when throttle position and throttle command differ by more than eight degrees. This may occur when a pilot overrides the throttles. HOLD also shows when the throttle command moves the throttles to the aft mechanical stop and the ASM continues to move.
EFFECTIVITY BEJ ALL 22-31-00
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D633W101-BEJ Sep 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
TMCS -A/T OPERATION -FLIGHT LEVEL CHANGE
EFFECTIVITY BEJ ALL 22-31-00
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D633W101-BEJ Sep 05/2002
TMCS -A/T OPERATION -SPEED
Mode Selection
In VNAV cruise, the speed (SPD) mode engages when all these conditions are true:
*
Autothrottle arm switches on
*
Airplane in the air more than 400 feet above ground level (AGL) BARO altitude
*
Takeoff (TO) mode not active
*
Go-around (GA) mode not active
*
Flight level change (FLCH) not active
*
Select the A/T switch on the mode control panel (MCP)
*
Default SPD selection (mode change from FLCH or VNAV).
Operation
The TMCF sends the A/T servo motor commands to move the throttles in the SPD mode to control the airplane speed. In VNAV, the MCP speed window is normally blank. Push the IAS/ Mach selector switch to unblank the speed window and show current FMCF target speed. Turn the selector to change FMCF target speed. The TMCF responds to speed window changes. Thrust limit, speed limit (Vmo/Mmo), and flap speed limit protection are active in this mode. SPD shows as the A/T mode on the primary flight display (PFD).
The A/T SPD mode can operate with or without an A/P pitch mode.
Climb/Continuous Switch
When two engines are in operation, this switch changes the autothrottle thrust reference to climb (CLB). When only one engine is in operation, it changes the thrust reference to maximum continuous (CON). The climb/continuous switch does not engage the autothrottle.
EFFECTIVITY BEJ ALL 22-31-00
Page 46
D633W101-BEJ Sep 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
TMCS -A/T OPERATION -SPEED
EFFECTIVITY BEJ ALL 22-31-00
Page 47
D633W101-BEJ Sep 05/2002
TMCS -A/T OPERATION -GO-AROUND
Mode selection
The go-around (GA) mode engages when all these conditions are true:
*
Autothrottle arm switches on
*
Airplane in the air
*
Glideslope active (engaged) or flaps not zero
*
Thrust limit mode not takeoff (TO)
*
Push either TO/GA lever.
Operation
The GA mode arms in approach when the flaps are down or glideslope is active. GA shows as the thrust limit mode on the EICAS display. Push any TO/GA lever to start the GA mode. The A/T mode annunciation goes to thrust (THR).
The TMCF commands the A/T servo motors (ASM) to move the throttles and control the airplane to 2000 feet per minute (FPM) vertical speed. Push any TO/GA lever again to start the full thrust GA mode. The A/T mode changes to thrust reference (THR REF). The TMCF commands the ASMs to move the throttles to the full GA thrust limit that shows on the EICAS display.
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