The analog inputs from the position and force transducers go to the A/D converter which changes them from analog to digital format. The transducers send signals from:
*
The control wheels
*
The control columns
*
The rudder pedals
*
The speedbrake lever.
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The pitch rate sensor is internal to the ACE. It sends analog input signals to the A/D converter and to the direct mode internal hardware. The ACE supplies the signals to the PFC for secondary mode.
The digital signals then go to the ARINC 629 buses.
D/A Converter
Digital commands from the buses go to the D/A converter which changes them from digital to analog format. They then go to the PCU servo loop to control the surfaces.
Direct Mode Select Logic
The pilots can manually switch the ACE to the direct mode. The PFC disconnect switch commands all ACEs to the direct mode.
The PFC automatically changes the ACE to the direct mode when data is not available from all three flight control buses or when internal monitors find failures. The ACE internal logic executes the command.
Direct Mode Command Calculation
In direct mode, the command calculation uses control laws contained in the ACE hardware. Position transducers, force transducers and the pitch rate sensor supply input signals. The analog command output signals go directly to the PCUs.
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PFCS -ACE -FUNCTIONAL DESCRIPTION
PCU Servo Loop Control
The ACE contains the servo loop control to each PCU. This servo loop operates in all three PFCS modes.
Failure Monitor
The failure monitor controls power to solenoids on the PCUs. When there is a failure, the ACE de-energizes solenoids on the effected PCUs.
Excitation Power Supply
The ACE has power supply circuits that supply 7v AC, 1800 Hz excitation power to the position and force transducers.
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PFCS -PFC -COMPONENT LOCATION
Purpose
The primary flight computers (PFC) calculate surface commands for the ailerons, flaperons, speedbrakes, spoilers, elevators, rudder and stabilizer.
These are the functions of the PFC:
*
Calculate control surface commands using pilot and autopilot inputs
*
Calculate commands for variable elevator feel and backdrive actuators
*
Supply stability augmentation
*
Supply flight envelope protection
*
Send signals for flight deck annunciations
*
Send signals for maintenance messages.
Physical Description
The PFC weighs approximately 38 pounds (17 kg). The PFC is passively cooled.
There are thirty-two program pins on each PFC. The program pins supply the following information:
*
Airplane type
*
Airplane model
*
Channel Identification (L,C,R)
*
Parity (odd).
You load the software of the PFC through the maintenance access terminal (MAT). There are no software options.
Location
The three identical and interchangeable PFCs are:
*
L PFC (left)
*
R PFC (right)
*
C PFC (center).
The L and C PFCs are in the main equipment center. The L PFC is on the E1-6 shelf and the C PFC on the E2-6 shelf. The R PFC is in the E16 rack aft of the front cargo door.
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PFCS -PFC -FUNCTIONAL DESCRIPTION
General
Each PFC has three independent lanes. The CPU of each lane is of different manufacture and part number. The lanes have identical software and capabilities. This is done to get the necessary redundancy. You use the MAT to load PFC software.
When the airplane initially gets electrical power on the ground, the PFCs do tests between lanes and between PFCs. These tests check the compatibility of software, hardware, airplane type and airplane model. Any lane or PFC that fails the tests is declared a failure.
Each lane has:
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An input signal monitor
*
A set of control laws
*
A cross-lane monitor
*
A PFC output selector.
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