M11.4 Flashcards
What are the two ways to separate water in the temperature control pack?
High-pressure loop or low-pressure loop
What is the function of the jet pump in the low-pressure system?
It sprays condensed water into the RAM air inlet duct to increase the cooling efficiency of the heat exchanger
What is a coalescer?
It is a strainer/gauze filter that combines water particles to make them into larger water droplets
When the differential pressure increases between the water separator inlet and outlet what does the pack controller assume is the fault and how does it counteract this?
It assumes that there is ice and counteracts this by opening the turbine bypass valve more
In a high-pressure loop what component could clog with ice?
The condenser
What is the minimum number of sensors you must have in a pack, and what are they?
Three; compressor discharge pressure temperature sensor, pack discharge temperature sensor and compressor overheat switch
If a pack controller fails, what protection is provided?
There is a backup pack controller
If the bypass valve fails in the open position what does the pack controller trigger and why?
Triggers the RAM air doors to open more, in order to keep the pack cool
What do the letters ECS stand for?
Environmental control system
On the ground, what position are the RAM air doors in?
They are fully open
What are the five things and air-conditioning system must provide?
Fresh, clean air, at a comfortable temperature and the correct humidity and pressure
What do regulations state about fresh air?
An acceptable limit of fresh air is 0.283 m³ per minute per person
What do we ensure about the cabin temperature?
That it ranges between 18 and 30°C
What does humidity of air depend on?
Air Temperature
Cabin pressurisation is a compromise between what?
Passenger comfort and structural design
Do you heat exchanges work using either: Conduction, convection or radiation?
Conduction
What is the function of the cooling pack?
It is to cool hot bleed air to a given value by the pack controller
What temperature and pressure is the bleed air at when it reaches the pack control valve?
200°C and 45 to 50 psi
What is the sequential process that the vapour cycle machine uses?
Evaporation, expansion, condensing and compression
What is the purpose of the ozone converter and what material is employed to do this?
To remove ozone by converting it to oxygen by using palladium
What is the purpose of the pack control valve?
It controls the amount of air that goes into the cabin
How is the pack control valve operated?
It is pneumatically operated and solenoid controlled
If the pack valve solenoid is energised and there is no flow, what position will the valve take and why?
Closed because of spring pressure
How does the air cycle machine cool air?
Hot air is cooled by the primary heat exchanger, then it is compressed which increases pressure and temperature, it then gets passed through the secondary/main heat exchanger is where temperature decreases and pressure stays the same and then the turbine expands the air reducing temperature and pressure and then cool air is produced.
If the compressor overheat sensor operates, what action will the pack controller attempt?
It will reduce flow through the pack control and open the RAM air doors more.
What does EBA stand for?
Engine bleed air
How many compressor stages are there for bleed air?
Two; intermediate pressure (IP) and high-pressure (HP)
Why is there a check valve fitted between intermediate and HP bleed off takes?
So that air that comes off the high-pressure line cannot bleed into the engine by the intermediate pressure line
How is pneumatic air distributed?
Via ducts
What are the three areas that are not pressurised?
Landing gear bays, tailcone and the radome