IGNITION SYSTEMS - FAA POWERPLANT
The ignition system provides the spark that ignites the fuel-air mixture in the engine cylinder at the correct time. This process is critical for efficient engine operation and power production.
Why Aircrafts Use Magnetos
Aircraft engines use magnetos instead of battery-powered ignition systems because magnetos are self-contained and do not rely on the aircraft electrical system. This ensures the engine continues to operate even if the electrical system fails.
Basic Operation (Simple Explanation)
A magneto generates electricity through electromagnetic induction. As the magnet rotates, it creates a magnetic field. When the breaker points open, the magnetic field collapses rapidly, inducing a high voltage in the secondary coil. This high voltage is sent to the spark plug to create a spark.
Main Components
. Magneto
. Breaker Points
.Capacitor (Condenser)
. Ignition Harness
. Spark Plug
Key Concept to Remember
The faster the magnetic field collapses, the stronger the spark produced at the spark plug.
Practice Questions
What is the purpose of a capacitor in a magneto ignition system?
The capacitor prevents arcing at the breaker points and helps the magnetic field collapse rapidly, producing a strong spark.
Why are magnetos used instead of battery ignition systems in aircraft?
Magnetos are self-contained and do not rely on the aircraft electrical system.
What happens when the breaker points open?
The magnetic field collapses, inducing high voltage and producing spark.
Oral Questions
. Explain how a magneto generates electricity
. What is the function of a capacitor?
. What happens if the capacitor fails?
. Why is ignition timing important?
Troubleshooting
. Weak spark - means the breaker points are worn, the magnet is weak or the capacitor is faulty.
. No spark- means
Open primary or secondary coil in the magneto
Failed capacitor (shorted or open)
Broken ignition lead (P-lead grounded)
Defective ignition harness
Fouled or damaged spark plugs
. Rough engine- fouled spark plug or incorrect timing or ignition lead issues.
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