Definition
A small resistor built into the center electrode of an aircraft spark plug that limits the peak current of the spark and reduces electrical noise. It suppresses radio interference from the ignition system and helps extend electrode life by controlling the discharge.
Plain English
A small part inside the spark plug that softens the spark. It cuts down the radio static the ignition system would otherwise create and helps the plug last longer.
Context Anchor
Seen in aircraft ignition system maintenance, spark plug inspection, and troubleshooting for rough engine operation or radio noise.
Derivation
Resistor comes from resist, meaning to hold back or oppose. In electrical use, a resistor opposes the flow of electricity. That fits this part because it does not stop the spark; it controls how sharply the spark current flows through the plug.
Why Pilots Care
Prevents interference with communication and navigation radios while controlling spark characteristics for reliable engine operation.
Analogy
It is like a small speed bump for electricity: the spark still gets through, but the sudden rush is controlled.
Intuition Check
The resistor is not there to make the spark stronger. It is there to control the spark current and reduce unwanted electrical noise.
Example Sentence 1
The mechanic replaced two spark plugs after testing showed the spark plug resistors had drifted out of tolerance.
Example Sentence 2
During the preflight, the pilot noted that worn spark plug resistors could affect both engine performance and avionics clarity.