Hydraulic System A powers which brakes?

• A. Inboard brakes
• B. Outboard brakes
• C. Both inboard and outboard brakes
• D. Nose wheel brakes only

Answer: (A)

Hydraulic systems on jets are split so different brake assemblies get pressure from dedicated sources. In this setup, System A feeds the inboard main-gear brakes. The inboard brakes are located near the fuselage centerline, and their hydraulic lines and pump supply go to those assemblies, giving them their braking pressure. The outboard brakes are supplied by a different system (System B), which is why System A doesn’t power them. Nose wheel brakes aren’t fed by System A in this arrangement either. So the brakes pressed by System A are the inboard brakes—the ones on the inboard main gear.