Is there ever a condition that allows hydraulic fluid to migrate from one system to another system?

Is there ever a condition that allows hydraulic fluid to migrate from one system to another system?

• A. No
• B. Yes
• C. Only during engine start
• D. Only on the ground

Answer: (A)

Hydraulic circuits are kept separate by design. The A320 uses three independent hydraulic systems, each with its own reservoir, pumps, lines, and isolation valves that prevent crossflow. Because of these barriers and check valves, there isn’t a normal path for fluid to move from one system to another. Only a fault condition—such as a valve failure, a leak that breaches a barrier, or a damaged line that ties the systems together—could allow migration. In normal operation, hydraulic fluid cannot migrate between systems.

Hydraulic circuits are kept separate by design. The A320 uses three independent hydraulic systems, each with its own reservoir, pumps, lines, and isolation valves that prevent crossflow. Because of these barriers and check valves, there isn’t a normal path for fluid to move from one system to another. Only a fault condition—such as a valve failure, a leak that breaches a barrier, or a damaged line that ties the systems together—could allow migration. In normal operation, hydraulic fluid cannot migrate between systems.