(b)
Direct law When the information required for the C* law is no longer valid or upon landing gear extension when the alternate law is active, the direct law in pitch is activated. The side stick movement directly controls the elevator position. The THS is mechanically controlled from the trim control wheel. No protection is included.
(c)
Mechanical control When the electrical flight controls are lost, the THS is mechanically controlled from the trim control wheel. The elevators are centered.
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(2) Lateral control After the loss of the normal pitch law or after certain system failures, the direct lateral law is activated. The side stick movements directly control the position of the ailerons and the spoilers 4 and 5. In the event of loss of these surfaces, reconfigurations are introduced to keep a sufficient roll rate:
-
if the two ailerons are no longer available, the spoilers 2 and 3 become active in direct law,
-
if the spoilers 4 are no longer available, the spoilers 3 become
active. After the loss of the normal lateral law, the yaw alternate law activated in the FACs ensures the Dutch-roll damping function.
(3) Abnormal condition law If the main aircraft parameters (Theta, phi., Vc, M, alpha) exceed predetermined limits, the abnormal condition law is activated i.e.:
-
in pitch control, the alternate law is active without autotrim,
-
in lateral control, the direct law is active,
-the rudder control is mechanical.
If the aircraft returns to level flight (0.9 g < Nz lower than or =
to 1.2 g) during 18s, the autotrim function is again active and the
alternate law for the rudder control is active. There is no reversion
to direct law when landing gear is extended.
B. Law Distribution in the Computers
The distribution of the laws in the computers is as follows: -------------------------------------------------------------------------------| COMPUTER | LAW | CONTROL | |-----------------------------------------------------------------------------| | | - PITCH NORMAL LAW | - 2 ELEVATORS | | | - PITCH ALTERNATE LAW | - 1 THS MOTOR | | ELAC | - PITCH DIRECT LAW | - 2 AILERONS | | | - LATERAL DIRECT LAW | | |----------------------|---------------------------|--------------------------| | SEC | - PITCH ALTERNATE LAW | - 2 PAIRS OF SPOILERS | | | - PITCH DIRECT LAW | - 2 ELEVATORS | | | - LATERAL DIRECT LAW | - 1 THS MOTOR | |----------------------|---------------------------|--------------------------| | FAC | - YAW ALTERNATE LAW | | -------------------------------------------------------------------------------
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C. Functional Statuses
The various functional statuses possible are:
-"normal law" status: the normal laws are active in pitch and lateral control,
-"alternate law" status: the laws, alternate in pitch and direct in lateral are active,
-"direct law" status: the direct laws are active in pitch and lateral
control. Upon loss of all the EFCS control laws, standby mechanical controls in pitch and yaw are possible.
D. Logic of Transition between Different Statuses The purpose of this logic is, after failure, to force law degradations in a computer and take into account the functional statuses then possible in all the computers. The "normal law" status can only be authorized when:
-
the ELAC having priority in lateral meets the requirements for engagement of the lateral normal laws,
-
the ELAC having priority in pitch meets the requirements for engagement
of the pitch and lateral normal laws. If one ELAC with priority on one axis no longer meets the requirements for the normal law, the "alternate law" status is adopted. If the computer which has priority in pitch does not meet the requirements for engagement of the alternate law, the "direct law" status is adopted.
7. System Reconfiguration Logic
____________________________
A computer is engaged on one axis if:
-
it has priority,
-
it has the capability to ensure control on this axis.
This capability is related to:
-its status,
-
the status of its servoloops,
-
the status of the hydraulic systems,
-
the status of the external sensors.
A.
Switching Logics
The switching logics are as follows:
-pitch control ELAC 2 ------> ELAC 1 ------> SEC 2 ------> SEC 1,
-lateral control ELAC 1 ----> ELAC 2. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：A320飞机维护手册 AMM FLIGHT CONTROLS 飞行操纵9(9)
