Which system provides pressure to the inboard brakes?

• A. 3
• B. 2
• C. 1
• D. 4

Answer: (A)

The main idea here is that braking pressure on an aircraft is provided by dedicated hydraulic circuits. The brakes aren’t all fed from a single source; each set of brakes is tied to its own hydraulic system so there’s still braking if another system fails.

In the diagram, the plumbing to the inboard brakes comes from a specific hydraulic circuit. When you press the brake pedal, the brake control valves route fluid from that circuit to the inner brake actuators, generating the pressure that clamps the inner wheels. The other hydraulic systems power other components or the outboard brakes, but they don’t feed the inboard brakes in this configuration. So the system shown feeding the inboard brakes is the one that provides the pressure.