Architecture for an airplane braking system including two computers and capable of withstanding two breakdowns, and a method of managing such an architecture

1. An architecture for a braking system for an airplane fitted with a plurality of undercarriages each carrying a plurality of wheels, at least some of which are fitted with brakes, the architecture comprising at least two braking computers each having two modules such that in each computer, one of the modules controls a first fraction of the brakes and the other module controls a second fraction of the brakes complementary to the first, the architecture being configured to operate in any one of the following modes of operation:

a first normal mode in which both modules of one of the braking computers are active for controlling all of the brakes and both modules of the other of the braking computers do not actively control the brakes;

a second normal mode in which both modules of the other braking computer are active for controlling all of the brakes and both modules of the one of the braking computers do not actively control the brakes; and

an alternative mode in which one module of one of the braking computers and one module of the other braking computer are active for controlling all of the brakes.

2. A braking system architecture according to claim 1 , wherein the modules include first monitoring means configured so that in each mode of operation the two active modules monitor each other.

3. A braking system architecture according to claim 2 , wherein each module comprises a first card adapted to generate a braking reference signal, and a second card adapted to generate a braking order for each brake associated with the module by modulating the braking reference signal in order to avoid skidding of said brake, the first monitoring means being associated with the first card of each module and being adapted to monitor the first card of the other active module.

4. A braking system architecture according to claim 3 , wherein the first card and the second card in a given module include second monitoring means configured, when said module is active, to enable the first and second cards to monitor each other.

5. A braking system architecture according to claim 4 , wherein the first card and the second card include at least one identical input.

6. A braking system architecture according to claim 1 , the architecture being configured also to operate in a degraded mode in which only one of the modules of one of the braking computers is active.

7. A braking system architecture according to claim 1 , wherein one of the modules of one of the computers is connected to a first power supply bus, one of the modules of the other computer is connected to a second power supply bus, and the other two modules that are intended to be active together in the alternative mode are connected to a third power supply bus.

8. A braking system architecture according to claim 1 , wherein each module is configured to perform at least one function other than braking and involving at least one of the undercarriages of the airplane, such as steering the airplane or lowering and/or raising the undercarriages.

9. A method of managing a braking system architecture for an airplane fitted with a plurality of brakes, the architecture comprising at least two braking computers each comprising two modules such that in each computer, one of the modules controls a first fraction of the brakes, and the other module controls a second fraction of the brakes complementary to the first, the method including the step of causing two modules each belonging to a different one of the braking computers to operate simultaneously for controlling all of the plurality of brakes, and the step of causing both modules of one of the braking computers to actively control the brakes while both modules of the other of the braking computers do not actively control the brakes.

10. A method according to claim 9 , wherein the two modules operating simultaneously monitor each other while they are operating simultaneously.