15.13 Starting & Ignition Flashcards
Does ignition occur before or after fuel is added?
Before.
When would the 2 engine systems operate individually?
Motor engine without ignition for maintenance.
Only ignition for relighting during flight.
What are the steps of engine starting?
- Ignition on
- Fuel on.
- Engine lights up.
- Engine attain self accelerating speed.
- Ignition off.
- Starter cuts out.
- Engine attains idle rpm.
How is the engine started?
By rotating the HP compressor.
What does the starter do once lite-off has occurred?
Continues to assist the engine until idle speed is reached.
Describe the cartridge started engine starter motor.
A small impulse type turbine driven by high velocity gases from a burning cartridge.
What does power output do in a cartridge started engine?
Passes through reduction gearbox and automatically disconnects.
What initiates the burning of the cartridge charge.
Electrically fired detonator.
How is the cartridge ignited?
By applying voltage.
Where is air starter used?
On most commercial jet engines.
What are the advantages of an air starter?
Lighter.
Simpler.
Economical.
How does the motor transmit power to the starter output shaft in an air starter?
Through a reduction gear and clutch.
What is the pressure of air used to start engines in an air starter?
30- 50 psi.
What does the clutch do as engine accelerates to idle rpm?
Auto disengages.
What does the transmission housing contain?
Reduction gears.
Clutch components.
Drive coupling
What does the transmission housing also provide?
Lubricating oil reservoirs.
What type of clutch assembly is used in an air starter?
Sprag clutch
What does the sprag clutch assembly incorporate?
Sight plug.
Magnetic drain plug (attracts ferrous particles).
What does the air starter valve have in case it fails to open?
A manual valve override.
What are the 2 types of engine starter systems?
Direct cranking.
Starter generator.
What does a direct cranking system use?
A DC motor.
Where is the direct cranking system used?
On small turbine engines, APUs, small turbo shaft engines.
What starting system is used on most GTE aircraft?
Starter generator.
What happens to the starter generator after functioning as a starter?
A second series of windings allow it to switch to a generator after engine is at idle.
Does the starter generator system have a clutch?
No as it is permanently engaged with the engine shaft.
What is the advantage of a starter generator system?
More economical.
Normally ignition is operated for a short time, when would continuous ignition be used?
When there’s a possibility of an engine flame out and to keep the engine from stopping.
What is more important during continuous ignition?
Cooling.
What air cools the ignitor lead?
Fan air.
What are the 2 ignition system types?
Which one is typically used?
Electronic.
Capacitor (typical).
What are the DC electrical power sources?
Battery.
115v AC
Permanent Magnet Generator.
What makes up a typical ignition system?
2 exciter units.
2 transformers.
2 ignition leads.
2 high tension leads.
Why are exciter units hermetically sealed?
To eliminate flashover possibility at altitude due to pressure change.
In a capacitor discharge exciter unit, where is energy stored ?
In capacitors.
In a capacitor discharge exciter unit, how many capacitors are in each exciter unit?
2
What can be said about an igniter plugs electrode?
It must be capable of withstanding a current of much higher energy.
What ignitor plug protrudes into the combustion chamber?
Annular gap igniter plug.
What igniter plug doesn’t protrude into the combustion chamber?
Constrained gap igniter plug.
What ignitor plug produces a more effective spark?
Annular gap ignitor plug
(Protruding type)
What ignitor plug produces a more effective spark?
Annular gap ignitor plug
(Protruding type)
