Definition
The procedure of setting the internal timing of a magneto on a workbench, before it is installed on the engine. The breaker points are adjusted to open at the precise moment the rotating magnet is in the position that produces the strongest spark, known as the E-gap position.
Plain English
Adjusting a magneto on the workbench so that its electrical contacts open at exactly the right point in the magnet's rotation to make the strongest spark. This is done before the magneto is bolted onto the engine.
Context Anchor
Seen in aircraft maintenance when a magneto is repaired, inspected, or prepared for installation on an engine.
Derivation
"Bench" refers to the workbench where the magneto sits during this procedure, separate from the aircraft. It distinguishes this step from "engine timing," which is done after the magneto is installed on the engine.
Why Pilots Care
Ensures reliable engine starting and smooth operation while preventing potential damage from incorrect ignition timing after installation.
Intuition Check
Bench timing does not mean timing the whole engine while it is running on a test bench. It means setting the magneto itself before it is installed on the engine.
Example Sentence 1
After overhauling the magneto, the mechanic completed the bench timing before reinstalling it on the engine.
Example Sentence 2
Bench timing lets the technician verify correct spark advance without the engine running.