15.13 Start and Igniton Flashcards
(26 cards)
What are the two main functions of a turbine engine starting system?
1) Rotate the HP compressor fast enough to bring in air
2) Ignite the fuel/air mixture in the combustion system
What are the four types of starting systems for turbine engines?
Cartridge starter
Air Turbine starter
Electric starter
Starter- generator
How does a cartridge starter work?
Burns a cordite cartridge to produce gas that spins a turbine, which drives the engine through gears
When the engine runs the turbine
What are the main advantages of air turbine starters?
Lightweight, simple, reliable, uses air from APU, ground cart or another engine
How is an air turbine starter disengaged after engine start?
The sprag clutch disengages once engine RPM exceeds turbine RPM.
What pressure is typically required for an air turbine starter?
Around 30–50 psi.
What are two maintenance tasks for air starters?
Check oil level and inspect magnetic chip detector.
How does a direct cranking electric starter work?
A DC motor turns the engine through a reduction gear and clutch until it self-sustains.
What is the main advantage of a starter-generator?
It serves as both starter and generator, saving weight and parts.
How does the undercurrent relay work in a starter-generator system?
It keeps the starter engaged until engine current draw drops, then disconnects the system.
What happens if the air starter valve fails to open?
Manual override can be used, requiring coordination between two engineers.
What might metal chips on a starter’s magnetic drain plug indicate?
Normal wear (fuzzy) or internal damage (slivers/chunks).
Why must the starter continue after ignition?
To assist until the engine reaches self-sustaining speed to prevent hot/hung starts.
What is a sprag clutch in an air turbine starter?
A mechanism that automatically disengages the starter once engine speed exceeds turbine speed.
Why are cartridge starters limited in use?
Cartridge size and explosive handling requirements limit their practicality.
What kind of oil is used in air turbine starters?
The same turbine oil as the engine, but it does not circulate through the engine.
Whats the main role of the ignition system in turbine engines?
To provide a spark to ignite the air fuel mixture during engine start
When is continuous ignition used?
Takeoff, landing, bad weather, or when there’s a risk of flameout.
What type of ignition system is most common in turbine engines?
High-energy capacitor discharge system.
What powers the ignition system?
Aircraft battery, 115V AC, or permanent magnet generator.
Why are there two exciters and two igniters?
For redundancy and reliability
How is cooling provided to ignition system components?
Fan air is ducted to cool the exciter and igniter leads
Whats the difference between annular gap and constrained gap igniters?
: Annular enters liner; constrained sits flush and sparks beyond liner.
What must be done before disconnecting high-voltage ignition leads?
Disconnect low-voltage first and wait at least 20 minutes after shutdown.
