M15.12 Air Systems Flashcards
Due to the large volumes of air, the engine maintains a temperature of what?
800-1150 degrees C
Where is the hottest section of the engine?
Around the turbines
What is the most critical lubricating point?
The exhaust turbine bearing
Three turbine engine cooling zones?
The fan case compartment
The intermediate compressor case compartment
The core engine compartment
What is Zone 1?
The area around the fan case that contains the accessory case and the electronic engine control
What is zone 2?
Cooled by fan air from the upper part of the fan duct and is exhausted at the lower end back into the fan air stream
What is zone 3?
The area around the high pressure compressor to the turbine cases. This zone contains fuel and oil lines.
Where can an indication of the anti icing valve being open be displayed?
On the engine parameters page
How is the compressor cooled?
The compressor rotor cavity is provided with cooling air from an intermediate compressor stage
The secondary airflow in the combustion chamber forms what types of cooling?
Removes heat from combustion liner
Creates a film which acts as thermal barrier between hot gases and combustion liner
Most common method of cooling components in turbine?
Engine bleed air
How are guide vanes and blades cooled?
By compressor discharge air
How are accessories cooled?
Air is ducted from intakes in the fan cowlings or from a specific stage of the compressor
How is the engine bearing chambers sealed?
By the LP compressor bleed air
What additional effect does the pressurised air acting on the air and oil seals have?
Additionally sealing effect to prevent oil escaping from bearing chamber
The air that enters the bearing compartments vents overboard through what?
The hollow N1 rotor shaft
Where is the external air usually bled from in the compressor?
The final or highest pressure stages
What services does engine bleed air help with?
Cabin pressurisation
De-Icing and anti-icing
Pneumatic starting of engines
Auxiliary drive units (ADU)
What type of ventilation occurs of the core compartment when engine operates?
Only positive
What is it known as when an engine bends after shutdown due to expansions?
Bowed rotor
