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
What are the two types of spark plugs electrodes?
-Massive ground spark plugs
-Fine wire spark plugs
How is capacitance afterfiring prevented?
A resistor is built into the spark plug
What is the gap of a spark plug?
The air gap between the center electrode and the ground electrode
