Definition
A self-contained ignition generator used on most piston aircraft engines that produces the full high voltage needed to fire the spark plugs directly within the magneto itself, then distributes it through shielded ignition leads to each spark plug.
Plain English
A magneto that makes the strong, high-voltage spark inside the unit and sends that finished high voltage out through the ignition wires to the spark plugs.
Context Anchor
Seen in piston-engine aircraft ignition system descriptions, maintenance discussions, and engine troubleshooting.
Derivation
High-tension' is an older electrical term meaning 'high voltage.' 'Tension' here refers to electrical pressure, not physical pulling. The name distinguishes it from a low-tension magneto, which produces only low voltage internally and relies on a separate transformer near each spark plug to step it up.
Why Pilots Care
It supplies the spark that ignites the fuel-air mixture, directly affecting engine starting, smooth running, and reliability in flight.
Intuition Check
Do not read “tension” as physical tightness here. In this term, “high-tension” means high voltage for making a spark.
Example Sentence 1
Most light piston aircraft use two high-tension magnetos for ignition redundancy.
Example Sentence 2
Maintenance on the high-tension magneto includes checking the distributor block for cracks that could cause misfiring.