Airbus A340 Series, Brochure

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STL 472.502/90 Issue 6
A340 Flight Controls - EFCS
5.4
Computers
Electrical control of the main surfaces is achieved by two
types of computers :
• Three Flight Control Primary Computers (PRIM) which
can process all three types of control laws (Normal,
Alternate, Direct)
• Two Flight Control Secondary Computers (SEC) which
can process the Direct Control Law.
These computers perform additional functions including :
• Speedbrakes and ground spoiler command
• Characteristic speed computation (PRIM only ) .
High-lift devices are commanded by two Slat/Flap Control
Computers
(SFCC) .
The SFCCs also command the aileron droop via PRIM or
SEC .
In order to provide all required monitoring information to
the crew and to the Central Maintenance System
(CMS) ,
two Flight Control Data Concentrators (FCDC) acquire the
outputs from the various computers to be sent to the
ECAM and Flight Data Interface Unit
(FDIU) . These two
FCDCs ensure the electrical isolation of the flight control
computers from the other systems.
Cockpit controls
Each pilot has a sidestick controller to exercise control
of pitch and roll.
The two sidestick controllers are not coupled
mechanically, and they send separate sets of signals
to the flight control computers.
Two pairs of pedals, which are rigidly interconnected,
give the pilots mechanical control of the rudder. The
pilots control speedbrakes with a lever on the center
pedestal.
The pilots use mechanically interconnected
handwheels on each side of the center pedestal to
control the trimmable horizontal stabilizer.
The pilots use a single switch on the center pedestal
to set the rudder trim.
There is no manual switch for trimming the ailerons.