Definition
In an aircraft hydraulic system, the specified kick-out pressure is the preset upper pressure limit at which the pressure regulator shifts from its 'cut-in' (loaded) position to its 'cut-out' (unloaded) position. When system pressure rises to this value, the regulator routes pump output back to the reservoir at low pressure rather than into the system, holding the system at full operating pressure until demand causes pressure to drop to the cut-in value, at which point the regulator shifts back and the pump again charges the system.
Plain English
It is the high-pressure point at which the regulator stops sending pump output into the hydraulic system and instead lets the pump run freely without building more pressure. The system stays pressurized for use, but the pump is no longer working hard against it.
Context Anchor
Seen in aircraft hydraulic or pneumatic system descriptions, especially when explaining how pumps and regulators control system pressure.
Derivation
The phrase 'kick-out' comes from the regulator mechanically 'kicking' a valve open at the set pressure, releasing the pump from the system. It captures the snap-action behavior of the regulator at the upper pressure limit.
Why Pilots Care
The kick-out pressure defines the top of the normal operating range. If it drifts high, components and seals can be over-stressed; if it drifts low, the system may not deliver full force when needed for landing gear, flaps, or brakes.
Analogy
It is like a home air compressor that stops pumping when the tank reaches its set pressure. The pressure has not disappeared; the control simply stops more pressure from being added.
Intuition Check
Do not read "shifts" as the whole regulator moving to a new location. In this context, it means an internal valve or control action changes state at a preset pressure.
Example Sentence 1
When hydraulic pressure reached the specified kick-out pressure, the regulator shifted and the pump output was routed back to the reservoir.
Example Sentence 2
When system pressure hit the specified kick-out pressure, the regulator shifted, unloading the pump.