Definition
A small spring-loaded device fitted around the brushes of a DC generator or motor that holds each carbon brush firmly against the commutator, ensuring continuous electrical contact as the brush wears down.
Plain English
A spring clip that keeps the carbon contact pieces in an electrical motor or generator pressed tightly against the spinning part they ride on, so the electrical connection stays solid as those pieces wear down over time.
Context Anchor
Seen during aircraft electrical component inspection, repair, or overhaul, especially around motors, generators, and starters.
Derivation
The word 'guard' here means 'something that holds in place' rather than 'something that protects from harm.' The brush guard guards the position of the brush against the commutator, not the brush against damage.
Why Pilots Care
Prevents propeller strikes and gear damage that could lead to loss of control or forced landings in remote areas.
Intuition Check
Do not read “brush guard” as a guard for plants, weeds, or cleaning brushes. In this context, it protects the electrical brush area inside a motor, generator, or starter.
Example Sentence 1
During the 100-hour inspection, the mechanic checked the brush guards in the generator to confirm each brush was still seating properly against the commutator.
Example Sentence 2
After touching down in tall grass, the helicopter's brush guard kept debris from reaching the skids and rotor head.