15.12, 15.13, 15.16, Flashcards
Define internal air system
No effect on thrust
4 functions of internal air system
Internal cooling , nacelle cooling, engine anti ice , customer air supply
Air used to cool nozzle guide vanes
Compressor air
Where is film cooling used
Turbine blades
Method to cool engine accessories
Fan air
Air used to cool turbine discs
Compressor air
Where’s bleed air tapped from
Compressor
How is tip clearance control maintained
ACC ( active clearance control )
Starter for turbo prop
Electric
Benefits of combined starter generator
Light weight
Used on corporate jets and some APUs
First step when starting APU
Turn battery switch on
What voltage is used in a high tension ignition plug to create ionisation of the air gap
20,000 volts
Where are DC starter motors used on large aircraft
“ heavy duty aircraft “ older turbo props
Where are starter generators usually used
Light business jets
Pressures or air starter
30 to 45 psi
Rotational speed of a starter
60 to 80,000RPM
How is a manual start achieved
Open butterfly valve with Allen key or spanner
3 purposes of ignition system
Ground start up , in flight start up ,
What part of ignition system is usually cooled
Igniter sleeve
2 forms of turbo prop engines
Free turbine
Single shaft
How are turbo props coupled with engine
- Free turbine : shaft is independent to that used to drive compressor
- single shaft : coupled to reduction gears from same shaft as compressor and turbine
Benefits of free turbine
Can go in feathered position on engine shut down
Prop and turbine can run at same speed
Where are spider and planet gears used
Reduction gear system
What prevents turbo prop over speed
Over speed governor
