Powerplant - AM.III.H.K1 - Ignition system theory Flashcards
What is the main advantage of a magneto ignition system over a battery ignition system for an aircraft reciprocating engine?
a magneto has its own source of electrical energy and is not dependent upon the battery
What is an all weather spark plug?
a shielded spark plug that has a recess in the shielding in which a resilient grommet on the ignition lead forms a weathertight seal
What is meant by the reach of a spark plug?
the length of the threads on the spark plug that screw into the cylinder head
What is the difference between a hot spark plug and a cold spark plug?
- hot spark plug has a long path for the heat to travel between the nose core insulator and the spark plug shell
- in a cold spark plug, the heat has a shorter distance to travel, and the spark plug operates cooler than a hot spark plug
What is the advantage of fine wire spark plugs over massive electrode spark plugs?
- fine wire spark plugs gave a firing end that is more open that that of a massive electrode spark plug
- the open firing end allows the gases that contain lead to be purged from the spark plug so they will not form solid lead contaminates
why is it important that the spark plugs be kept in numbered holes in a tray when they are removed from an engine?
- spark plugs tell a good deal about the internal condition of the cylinders from which they were taken
- by knowing the cylinder from which each spark plug came, the mechanic can take the proper action when a spark plug indicates such conditions such as detonation or overheating
why is it important that a torque wrench always be used when installing spark plugs in an aircraft engine?
- if spark plugs not tight enough, there’s a possibility of a poor seal
- the they are too tight, there is danger of cracking the insulation of damaging the threads on the spark plug or cylinder
what kind of gauge should be used to measure the electrode gap in aircraft spark plugs?
a round wire gauge
