Ignition Systems Flashcards
What is in a high energy discharge igniter plug?
Large storage capacitor in the ignition exciter
Ignition Units are rated in ________
Joules
How many watts per second is one joule?
1 watt per second
What joule rating will large turbofan systems?
16 Joules
Smaller engines Ignition system?
1 Exciter unit, 2 Individual high tension cable assemblies and 2 spark igniters
Larger engines ignition system?
1 Ignition exciter per igniter plug
What is the normal spark rate?
60-100 sparks per minute
Ignition Exciters can be classified as:
Intermittent duty or Continuous Duty
How do modern ignition systems ignite?
They use a solid state exciter (Continuous Duty)
What do bleed resistors within the exciter box do?
1) Dissipates excess voltage
2) Provides a discharge path
3) Bleeds off capacitor charge when the system is de-energized
Igniters are made up of 4 basic parts?
Insulators, Electrodes, Shell Body, Internal Seals
What are Insulators made of?
Aluminum Oxide Ceramic
What are Electrodes made of?
Iridium or Tungsten
What are shell bodies made of?
Stainless Steel/Inconel
Igniters will have a _________ ______ drilled around the perimeter of the plug tip that keeps it 500-600F cooler than the surrounding gas temperature
Cooling Hole
What should you always do when installing igniter plugs?
Always use new gaskets
What may some smaller gas turbine engines use instead of Igniter plugs?
Glowplugs
Do glowplugs have a higher or lower power output than a system with igniters?
Higher
Each lead assembly consists of ….
an electrical cable contained in flexible metal braiding
_________ _______ at each end of the assembly facilitate its connection to respective connectors
Coupling Nuts
What is the auto-ignition system designed to do?
Provide automatic ignition when engine torque or power falls too low, ensuring ignition during takeoff, landing, turbulence and icing conditions
On a lead-pin style connection, what should a retention test read at minimum?
0.125 lbs
