Module 15.13 Start & ignition Flashcards
What do some aircraft use for engine starting?
- Electric
- Gas pressure
- Hydraulic
What are there two separate provisions to start a GTE?
- Provisions to rotate the compressor to induce sufficient airflow through the engine
- Provision for fuel ignition
A cartridge starter uses what type of turbine blades?
Small impulse type
Cartridge starters are driven by high velocity air driven by what?
A burning cartridge
What is the power output of the turbine passed through?
Reduction gearbox
How is the cartridge ignited?
Applying a voltage through connector at the end of the breech handle
What are the benefits to air starters?
Light, simple to operate and economical
How does the clutch disengage?
Automatically, if it is a sprag clutch it will disconnect at a certain centrifugal force
What psi is required for an air starter?
30-50 psi
What type of clutch does an air starter have?
Sprag
Does the starter motor have its own oil system?
Yes, separate from the engines
How do you turn off the air starter motor?
Close the starter valve
What type of drain plug is in the starter transmission?
Magnetic, to catch particles in the oil
What gear system is used in a starter motor?
Reduction gear system
How can the engine be started if the start valve is inoperative?
Manual valve override
What are the 2 types of electrical starter on a GTE?
- Direct cranking
- Starter-generator
What current is a a direct cranking starter supplied by?
Direct
What engines are direct cranking starters used on?
- Small turbine (APU)
- Small turboshaft
How does a starter generator work?
Acts like a direct cranking starter but once the engine has started there is a secondary series of windings which allow for generation
Does the starter-generator system have a clutch?
No, it is permanently mounted to the gearbox
What is the advantage of a starter generator?
Saves weight
How long are igniters lit for usually?
A short period
What can be said about the igniter voltage during continuous ignition?
Lower
When would continuous ignition be used?
- Takeoff, landing
- Abnormal conditions/ emergency
How are the igniter leads cooled?
Fan air
What are the two igniter types?
- Capacitance
- Electronic
What are the 3 electrical systems that power ignitors?
- 115 vac
- Aircraft battery
- Permanent magnet generator
What does a typical ignition system consist of?
- Two exciter units
- Two transformers
- Two intermediate ignition leads
- Two high tension leads
What is eliminated by hermetically sealing the igniter box?
Eliminate flashover possibility
How many capacitors are in a capacitor discharge unit?
2
What is the discharge of the second capacitor?
Low voltage, high energy
What can the high energy of the spark plug cause?
Electrode erosion
What igniter plugs protrude into the chamber liners?
Annular gap
What igniter plug operates at a much cooler temperature?
Constrained gap plug
Does a constrained gap plug protrude into the chamber?
No, hence the cooler operating temperature
What drops the resistance in the Capacitor discharge exciter unit, to allow for the high energy low voltage spark?
The first capacitor sparking
