BSCU

BRAKE AND STEERING CONTROL UNIT
unité de contrôle de la direction et des freins

Braking/Steering Control Unit: The BSCU controls the operation of the electrohydraulic valves in the system. The BSCU has control of primary functions as the quantity of braking, the anti-skid function (to give maximum braking efficiency), the automatic braking of the main wheels during the L/G retraction, the nose wheel steering.

The BSCU also has these secondary functions, like monitoring the brake temperature, doing a residual pressure check in the brakes, reading the wheel speed signals, using Built-In Test Equipment (BITE) to do software controlled tests and supplying data to other systems in the aircraft.

The BSCU has two isolated channels, Channel 1 and Channel 2. Each channel connects to its related electrical subsystem. Only one channel (the active channel), controls the operation of the system. The other channel (the standby channel) is available if the active channel becomes unserviceable. If available, the two channels monitor the operation of the system. When the BSCU is supplied with power Channel 1 becomes active. After each landing the BSCU makes a record in an Electrically Erasable Programmable Read-Only Memory (EEPROM) of which channel was active during the landing. Before the next landing, the BSCU reads the EEPROM and makes active the channel that was standby during the last landing.

A tachometer is installed at each end of the MLG axles. A drive assembly connects the tachometer to the related MLG wheel. The tachometer measures the speed of the wheel and sends this data to the BSCU. The BSCU uses this data to control the hydraulic pressure supplied to the related brake.