Ignition Systems

Question 1

What is in a high energy discharge igniter plug?

Answer 1

Large storage capacitor in the ignition exciter

Question 2

Ignition Units are rated in ________

Answer 2

Joules

Question 3

How many watts per second is one joule?

Answer 3

1 watt per second

Question 4

What joule rating will large turbofan systems?

Answer 4

16 Joules

Question 5

Smaller engines Ignition system?

Answer 5

1 Exciter unit, 2 Individual high tension cable assemblies and 2 spark igniters

Question 6

Larger engines ignition system?

Answer 6

1 Ignition exciter per igniter plug

Question 7

What is the normal spark rate?

Answer 7

60-100 sparks per minute

Question 8

Ignition Exciters can be classified as:

Answer 8

Intermittent duty or Continuous Duty

Question 9

How do modern ignition systems ignite?

Answer 9

They use a solid state exciter (Continuous Duty)

Question 10

What do bleed resistors within the exciter box do?

Answer 10

1) Dissipates excess voltage
2) Provides a discharge path
3) Bleeds off capacitor charge when the system is de-energized

Question 11

Igniters are made up of 4 basic parts?

Answer 11

Insulators, Electrodes, Shell Body, Internal Seals

Question 12

What are Insulators made of?

Answer 12

Aluminum Oxide Ceramic

Question 13

What are Electrodes made of?

Answer 13

Iridium or Tungsten

Question 14

What are shell bodies made of?

Answer 14

Stainless Steel/Inconel

Question 15

Igniters will have a _________ ______ drilled around the perimeter of the plug tip that keeps it 500-600F cooler than the surrounding gas temperature

Answer 15

Cooling Hole

Question 16

What should you always do when installing igniter plugs?

Answer 16

Always use new gaskets

Question 17

What may some smaller gas turbine engines use instead of Igniter plugs?

Answer 17

Glowplugs

Question 18

Do glowplugs have a higher or lower power output than a system with igniters?

Answer 18

Higher

Question 19

Each lead assembly consists of ….

Answer 19

an electrical cable contained in flexible metal braiding

Question 20

_________ _______ at each end of the assembly facilitate its connection to respective connectors

Answer 20

Coupling Nuts

Question 21

What is the auto-ignition system designed to do?

Answer 21

Provide automatic ignition when engine torque or power falls too low, ensuring ignition during takeoff, landing, turbulence and icing conditions

Question 22

On a lead-pin style connection, what should a retention test read at minimum?

Answer 22

0.125 lbs