The ignition system

Magnetos, dual ignition, the pretakeoff mag check, and the ground-safety rules that follow from it.

9 min read · The airplane: engine and systems

After this lesson you can

  • Explain why a magneto needs no electrical power from the aircraft to fire the spark plugs.
  • State why most certificated aircraft engines fire two spark plugs per cylinder from two separate magnetos.
  • Perform and interpret a pretakeoff magneto check, including what a normal drop and a "no drop" result each mean.
  • Explain why a propeller must always be treated as if the ignition were live.

Dual magneto ignition is one of the few features that sets an aircraft engine apart from a car engine. It buys redundancy and a small performance gain, but it also creates a specific, well-documented hazard around the propeller that every pilot has to internalize before ever touching one.

The rest of this lesson

  1. 1.A self-contained ignition source
  2. 2.The ignition switch
  3. 3.The pretakeoff mag check
  4. 4.Reading the result
  5. 5.Ground safety around the propeller

These 5 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.

See what the PPL track costsEvery module 1 is free to read, no account, no card.

Key terms

Try to recall each definition before turning the card.