*
Flight control position transducers
*
Flight control force transducers
*
FSEUs
*
Primary flight computers DISC/AUTO switch
*
Thrust asymmetry compensation switch
*
AIMS cabinets
*
PCUs.
Rudder Trim Selector and Manual Trim Cancel Switch
The rudder trim selector and the manual trim cancel switch supply signals to the ACEs. These signals show the pilot commands for rudder trim.
Pitch Trim Switches
The pitch trim switches supply signals to the ACEs to show the pilot pitch trim commands.
Flight Control Position Transducers
The flight control position transducers supply electrical inputs to the ACEs. They show the position of the:
EFFECTIVITY
BEJ ALL
*
Control wheel
*
Control column
*
Rudder pedals
*
Speedbrake lever.
Flight Control Force Transducers
The pitch and roll force transducers supply signals to the ACEs. The signals show when the pilot applies a force to the control wheel or control column.
FSEUs
The FSEUs supply a signal to each ACE showing that the flaps and slats are retracted or not retracted.
Primary Flight Computers DISC/AUTO switch
The primary flight computers DISC/AUTO switch supplies a signal to each ACE that shows the switch position. Switch positions are AUTO or DISC.
Thrust Asymmetry Compensation Switch
The thrust asymmetry compensation (TAC) switch supplies a signal to the C ACE that shows the switch position. The switch positions are AUTO or OFF.
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PFCS -ANALOG INTERFACES
AIMS Cabinets
Each ACE supplies two signals to both AIMS cabinets. The signals show that the ACE is in the direct mode and the ACE power supply is correct.
PCUs
The ACEs supply command signals to the PCUs. The PCUs supply position feedback signals to the ACE.
EFFECTIVITY BEJ ALL 27-02-00
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777 AIRCRAFT MAINTENANCE MANUAL
PFCS -ANALOG INTERFACES
EFFECTIVITY BEJ ALL 27-02-00
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PFCS -ELECTRICAL POWER DISTRIBUTION
General
Because the electrical power supply to the PFCS is very critical, a high level of redundant power is available.
Power Supply Assembly
Three identical power supply assemblies (PSAs) supply 28v dc to the components of their on-side portion of the PFCS. The PSAs supply electrical power to the ACEs, the PFCs, the PCUs and the STCMs. In addition, the PSAs supply power for the rudder trim, the auto speedbrake, the ADMs and the SAARU.
See the flight controls dc power section for more information (SECTION 24-35).
PSA Power Sources
During flight, the left PSA normally receives primary power from one permanent magnet generator (PMG) on the left engine. The right PSA receives primary power from one PMG on the right engine. The center PSA receives primary power from two PMGs, one on each engine. The PSAs change the ac variable electrical power from the PMGs to 28v dc.
If the primary power is not available or not within specified limits, the left and right PSAs change to secondary power from the left and right 28v dc buses. Secondary power to the center PSA is from the captain’s flight instrument bus.
EFFECTIVITY
BEJ ALL
When the airplane is on the ground and no engines are running, the PSAs normally change to secondary power.
If primary and secondary power is not available or not within specified limits, the PSA changes to backup power. The left and center PSAs receive backup power from the hot battery bus. The right PSA has no backup power.
Each PSA has a dedicated flight control dc battery (FCDC BATT). It supplies the flight control components with power for one minute during PSA switching.
Power to L2 ACE
The L2 ACE and its related PCUs have only one power supply from the left 28v dc bus in the P110 left power management panel. In addition, the left 28v dc bus supplies power for the stabilizer commands, the elevator feel and the aileron/rudder trim module.
Training Information Point
There are circuit breakers on the front of the PSAs and the P110 left power management panel. They control power to the components of the PFCS.
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PFCS -ELECTRICAL POWER DISTRIBUTION
If electrical power is shutdown with a PFC deactivated or removed, the FCDC battery discharges. To prevent FCDC battery discharge, open the applicable circuit breakers on the PSA. When electrical power is available, close the circuit breakers.
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