Where are quick-disconnect fluid line couplings normally used in an aircraft hydraulic system?

• A. In the cabin air lines.
• B. In the lines that connect the engine-driven pump into the hydraulic system.
• C. In the fuel lines.
• D. In the landing gear actuators.

Answer: (B)

Quick-disconnect fluid line couplings are placed at the interface where the engine-driven hydraulic pump connects to the rest of the hydraulic system. They’re designed so the pump can be removed or serviced without draining the entire system, making maintenance quicker and cleaner. The coupling seals automatically when disconnected, minimizing fluid loss and preventing air from entering the circuit, and it allows the pump assembly to be separated from the lines for servicing. This is why they’re used at the pump connection rather than in cabin air lines (which are pneumatic), fuel lines, or other locations like actuator lines. The pump connection point is the practical, standard spot for this feature to simplify removal and replacement during engine or pump maintenance.