Definition
The low-pressure side of a hydraulic system that carries fluid from the actuators back to the reservoir after it has done its work, completing the closed-loop circulation of hydraulic fluid.
Plain English
The path that used hydraulic fluid takes to flow back to its storage tank after it has pushed or moved something. It is the return half of the loop.
Context Anchor
Seen in diagrams of hydromechanical flight control systems, where pressure lines send fluid to a control device and return lines carry it back.
Derivation
Hydraulic comes from the Greek hydor, meaning water, originally describing systems that moved water through pipes. Return simply means going back. Together it points to fluid travelling back to where it started, ready to be pumped out again.
Why Pilots Care
A functioning hydraulic return keeps fluid circulating so flight controls remain responsive without loss of pressure or system overheating.
Analogy
Think of a sink with a faucet and a drain. The pressure side is like the faucet sending water out; the hydraulic return is like the drain path that lets the fluid go back where it belongs.
Intuition Check
Do not read return as a command to move a control back to neutral. Here it means the fluid’s path back to the reservoir after it has passed through part of the system.
Example Sentence 1
After the actuator moved the control surface, the fluid flowed through the hydraulic return line back to the reservoir.
Example Sentence 2
During inspection, the mechanic checked the hydraulic return lines for leaks that could reduce control authority.