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BCM
Also from: Brake control module
There are 2 BCMs in the MAUs. BCM 1 controls the outboard brakes (1 and 4), while BCM 2 controls the inboard brakes (2 and 3). Located in the MAU. The BCMs calculate a pressure command for each wheel brake given the brake pedal position. When WOW indicates inflight, with the gear lever not down and the gear not down and locked, pressure is applied to all wheels for 4s.
Touchdown protection
Brake pressure is modulated by the antiskid system, and inhibited inflight and for 3s after WOW, unless overridden by spin-up override where wheel speed is >50kts.
Locked wheel protection
Brake pressure may also be reduced if one wheel in a pair (either inboard or outboard) has a speed <33% of its partners speed, with a speed >30kts.
Brake control valves
10s after airborne, with the gear lever up and a wheel speed 0, the valves are deenergised, isolating hydraulic supply to the valves. This depressurises the brake system during flight. The valves are reenergised with the gear lever down.