Ignition Systems Flashcards
Why does the FAA require engines to have a redundant ignition system?
For safety
What are the three circuits in a magneto?
-Magnetic
-Primary
-Secondary
What is the purpose of a capacitor in a magneto?
-To aid in the collapse of the magnetic field
-Prevents arcing across the breaker
Components in a magnetic circuit?
-Rotating magnet
-Soft iron core
-Pole shoes
Components in a primary circuit?
-Primary coil
-Cam actuated breaker points
-Capacitor
-Ignition switch
Components of a secondary circuit?
-Secondary coil
-Distributor rotor and block
How is the amount of voltage induced into primary coil by the rotating magnet determined?
-Rate at which the flux through the core changes
-Number of turn of wire in the coil
How is the voltage in the secondary coil determined?
-Rate at which the magnetic field collapses
-The number of turns in the primary and secondary windings
What are the two ways to temporarily retard the the timing of the spark plug?
-Impulse coupling system
-Shower of sparks
What is flashover?
At higher altitudes higher voltage has a tendency to jump to the wrong electrode in the distributor due to the lower resistance of the thinner air.
What are the three main components of a spark plug?
-Electrode
-Insulator
-Outer shell
What prevents gas from escaping around the plug?
-Close tolerance screw threads
-Copper gaskets
How is the size of a spark plug determined?
Diameter
Threads per inch
What is the heat range of a spark plug?
The measure of a spark plugs ability to transfer the heat of the combustion to the cylinder head
Why are ignition leads shielded?
To absorb electromagnetic interference
