The side stick controller operation for the pitch control is similar to the roll control as described in para. 1.B.
F. Trimmable Horizontal Stabilizer (Ref. 27-40 and 27-90) The pitch trim function is achieved by the Trimmable Horizontal Stabilizer (THS) either automatically in normal in-flight manual mode or autopilot function or manually from the handwheels in normal ground operation or in-flight failure condition. The THS is moved and held by a THS actuator that includes a double load-path ball screw powered by two differentially coupled hydraulic motors mechanically servocontrolled. The ball screw is fitted with a no-back brake, the motors are fitted with pressure-off brakes. The control loops include a device that applies both pressure-off brakes in the event of either control valve jamming. The input shaft of the THS actuator is normally driven by an electrical motor servocontrolled by the ELAC 2, two other motors controlled respectively by ELAC 1 or SEC 1 and SEC 2. The input shaft of the THS actuator can also be manually driven by the pilots through a mechanical linkage normally moved by the handwheels. An overriding mechanism gives the priority to the mechanical control over the electrical control.
G. Spoilers Five spoiler surfaces are provided on each wing to achieve the functions below :
-roll spoiler (surfaces 2 to 5)
-speedbrake (surfaces 2 to 4)
-ground spoilers (all surfaces).
These surfaces are manually controlled from the side stick controllers
(roll spoilers), speedbrake control lever (speedbrake) or automatically
in autopilot and ground spoiler function.
Each surface is controlled by one servocontrol supplied from the Green,
Yellow or Blue system and signalled from the SEC 1, 2 or 3.
The combination of the different functions is achieved in the computers.
In the event of an electrical failure, the associated surface is
hydraulically held down. In the event of a hydraulic failure, the
servocontrol is hydraulically locked in one direction to prevent the
surface from raising. In both cases the control of the symmetrical
surface is automatically inhibited.
H. Electrical Flight Control System
(1) General (Ref. Fig. 002) The Electrical Flight Control System includes the ELACs, the SECs, the Flight Control Data Concentrators (FCDCs) and vertical accelerometers.
1EFF : ALL 1 27-00-00Page 7 1 1 Aug 01/04R 1 1 1CES 1
Electrical Flight Control System Architecture Figure 002
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The EFCS is built according to the principles below :
(a)
Redundancy and dissimilarity The EFCS includes two ELACs, three SECs, two FCDCs and four accelerometers. The ELACs and SECs are both able to achieve the roll and pitch control of the aircraft. These two types of computer differ by their internal architecture, hardware, type of microprocessor, software. For each computer type, the control and monitoring software are different.
(b)
Monitoring The monitoring of each computer (ELAC, SEC) is achieved as follows:
-Monitoring channel: Each computer consists of two physically and electrically-separated channels, one being dedicated to the control functions, the other to the monitoring of these. These two channels perform the actuator command signal computation using different digital processes. The monitoring channel permanently compares the results of these computations and inhibits the signal to the actuator, should a discrepancy occur.
-Self-monitoring capacity : Each channel is able to detect the failure of the critical signals it receives or emits and to detect internal failures by test of the processor and monitoring of its internal power supply.
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