Powerplant - Ignition Systems

Question 1

What is a magneto?

Answer 1

A special type of engine driven AC generator that uses a permanent magnet as a source of energy. The magneto develops a high voltage that is used to fire the spark plugs.

Question 2

Where is the E-gap position in a magneto?

Answer 2

A few degrees past the neutral position

Question 3

What is the piston position when the spark occurs in a cylinder?

Answer 3

A few degrees before top dead center of the compression stroke

Question 4

What is a duel magneto ignition system?

Answer 4

Two magnetos in one housing, with one rotating magnet and cam, common to two sets of breakers points and coils.

Question 5

When the ignition is in the OFF position, what is the condition of the primary?

Answer 5

It is completed through the ignition switch to the ground

Question 6

In a dual magneto ignition system, what part of the system is grounded when the ignition switch is placed in the RIGHT position?

Answer 6

The left magneto circuit will be grounded

Question 7

What is internal timing of the magneto?

Answer 7

Adjusting the breaker points to open when the rotating magnet is at the E-gap position

Question 8

What is the purpose of an impulse coupling used with a magneto?

Answer 8

To spin the magneto rapidly to produce a hot spark for starting the engine and at the same time, retard the timing of the next spark

Question 9

What is staggered timing ignition?

Answer 9

The firing of one spark plug before the other, instead of firing them simultaneously

Question 10

What type of ignition system is used in most turbine engines?

Answer 10

An electronic capacitor type ignition system

Question 11

When are turbine engine ignition systems normally in use?

Answer 11

For starting and restarting an engine only

Question 12

What are two types of igniter plugs?

Answer 12

annular gap and constrained

Question 13

What is the purpose of the condenser in a high tension magneto electrical system?

Answer 13

To prevent arcing at the points and to hasten the collapse of the magnetic field around the primary coil

Question 14

What are the three major circuits of a high tension magneto system?

Answer 14

The magneto circuit, primary electrical circuit, and secondary electrical circuit

Question 15

What are the components of a high tension magnetic circuit?

Answer 15

A permanent rotating magnet, soft iron core, and pole shoes

Question 16

What is the piston position when the spark occurs in a cylinder?

Answer 16

The piston is a specified number of degrees before top dead center on the compression stroke

Question 17

What is proper spark plug reach?

Answer 17

When the electrode end of the plug inside the cylinder is in the best position to achieve ignition

Question 18

Why is it important to keep track of the cylinders that spark plugs are installed in?

Answer 18

Because spark plugs can provide a lot of information about the health of a specific cylinder

Question 19

What is the function of the igniter plugs in a turbine engine?

Answer 19

To provide a discharge gap for the current, which is stored in the capacitor. The discharge results in a high intensity spark which ignites the fuel-air mixture

Question 20

How can you tell if a starter commutator is dirty or worn?

Answer 20

An excessively noisy starter

Question 21

What does it mean when the starter relay clicks when the starter switch is placed in the “start” position?

Answer 21

The supply voltage is too low to supply enough current to the relay coil to fully engage the contact points.

Question 22

What is an advantage of air turbine starters, when compared to electric starters, for large turbine engines?

Answer 22

They are light weight, and do not have the same cool down periods as electric starters.

Question 23

Why do turbine ignitors not get carbon fouled as often as reciprocating engine spark plugs?

Answer 23

Due to the extremely high rates of electrical discharge in the turbine ignitors

Question 24

What are the three parts of an ignition systems of a turbine?

Answer 24

Exciter, Ignition lead, and Ignitor