Which hydraulic color is associated with the parking brake operation?

Which hydraulic color is associated with the parking brake operation?

• A. Blue
• B. Green
• C. Red
• D. Yellow

Answer: (D)

Hydraulic color coding identifies which circuit handles each function, and the parking brake is tied to the yellow system. On the A320, the three color-coded hydraulic circuits are blue, green, and yellow. The parking brake uses the yellow circuit (System 3), giving it a dedicated source of hydraulic pressure to hold the brakes when the aircraft is parked. This separation ensures the parking brake remains functional even if the other hydraulic systems are in use or degraded. The blue and green circuits power the other primary flight-control and braking functions during normal operations, but the parking brake relies on yellow for independent operation on the ground.

Hydraulic color coding identifies which circuit handles each function, and the parking brake is tied to the yellow system. On the A320, the three color-coded hydraulic circuits are blue, green, and yellow. The parking brake uses the yellow circuit (System 3), giving it a dedicated source of hydraulic pressure to hold the brakes when the aircraft is parked. This separation ensures the parking brake remains functional even if the other hydraulic systems are in use or degraded. The blue and green circuits power the other primary flight-control and braking functions during normal operations, but the parking brake relies on yellow for independent operation on the ground.