Air Systems Flashcards
Define internal air system
Airlfow that does not directly contribute to the engine thrust
Internal functions for safe and efficient operation of engine
A.Sealing of bearings, chambers and labyrinth seals
B. Ventilation (purge) of torch igniters
C. Anti icing
D. Air pressure to the FCU
E. Pressure balancing of HP and power turbines
F. Internal cooling
External functions for safe and efficient operation of engine
A. Cabin air conditioning
B. Sand filter system
C. Winch motor operation
D. Cooling accessories
Internal cooling
How are mainshaft and main bearings cooled
Main shafts = by cooled compressor air fed through the bearing housing in the hollow shaft
Main bearing = cooled by lubricating oils
Cooling of Seals
The air being at greater pressure than oil migrates through the labyrinth seal preventing an oil loss. It is this air that has to be removed from scavenge system
Pressure balancing
Compresor blads have Aerofoil sections = generate thrust
Reduce loading HP pressure air is fed onto the opposing face to reduce this loading
Cooling of Combustion chamber components
Ducts cooled air between the outer wall and flame tube
Cooling Turbine assembly
Air is tapped from compressor delivery and fed through the hollow turbine blades to reduce their temperature
External accessories
Excess heat from friction in gears are conducted by lubrication oils
What else is used in (starter/generator) ?
Atmospheric air, ducted through intake louvres or may be tapped from compressor
Engine ice prevention systems has two forms
Hot air
Electrical
Where is the air taken from in hot air system
HP areas of the compressor
What is the electrical ice prevention device
Heater mat
Made from neoprene or glass cloth impregnated with resin
When anti icing is switch on the pilot may see
Slight rise in JPT ( Jet pipe temperature)
Slight drop in engine RPM
