Definition
An electrical switch that automatically opens (disconnects) a circuit when a specified condition is reached, removing power from a component to protect it or to stop its operation. Cutout switches are typically actuated by pressure, temperature, position, or current, rather than by the pilot.
Plain English
A switch that shuts something off by itself when a set limit is reached, so the system stops drawing power or stops operating.
Context Anchor
Seen in aircraft electrical and system descriptions, such as landing gear, flap, pump, generator, or protection circuits.
Derivation
From 'cut out,' meaning to remove or disconnect. The switch literally cuts the circuit out of operation when its trigger condition is met.
Why Pilots Care
Allows a pilot or mechanic to safely disable a faulty circuit and prevent electrical damage or fire without affecting other systems.
Intuition Check
Do not assume a cutout switch is always a cockpit switch the pilot moves by hand. Many cutout switches work automatically inside the aircraft system.
Example Sentence 1
When the landing gear reaches the fully retracted position, a cutout switch opens the circuit and stops the hydraulic pump.
Example Sentence 2
During troubleshooting the mechanic used the battery cutout switch to de-energize the avionics bus.