Air Conditioning + Pressurisation Flashcards
What 3 sources of air are there on an Aircraft (2 in flight and on ground, 1 on ground only)
- Engine Bleed Air
- Auxiliary Power Unit
- High pressure ground connectors
What 3 types of air can be taken from the engine?
- Fan Air
- Intermediate Pressure
- High Pressure
What does the check valve on the Intermediate Pressure stage protect against and when is it used?
Protects the compressor from backflow (compressor stall) when Air is being taken from the High Pressure stage
What does a fan air valve do?
Allows more or less fan air to pass the pre cooler
Through what 2 methods (1 manual, 1 automatic) is control of the pneumatic system achieved?
- pneumatic control panel in flight deck
- pneumatic controller
How many pneumatic controllers are there on each engine bleed air system?
1 per engine
What areas of the aircraft does the air conditioning system pressurise?
- Passenger compartment
- All Cargo compartments
- Flight deck
- Avionics Compartment
How often must cabin air be exchanged to ensure freshness?
Every 3-5minutes
What two devices are fitted to keep air clean?
- Air filters
- Ozone converters (At high altitudes)
What is the permitted temperature range to ensure passenger comfort?
18-30 degrees Celsius
Why is water separated from the air? (2 reasons)
- Prevents parts and valves freezing
- Stops fog and water droplets forming in the cabin
What is considered the ideal cabin altitude?
8000ft
What Valves regulates the flow of bleed air from the pneumatic system into the air conditioning system?
Pack valves
What do air conditioning packs do to pneumatic bleed air?
Cool it to a basic temperature
What does the mixing unit mix?
Cold air from the packs with recirculated cabin air
What is trim air?
A certain amount of hot air that comes from upstream of the packs that makes the final adjustment to the temperature of the air leaving the mixing unit
What do Pack controllers regulate?
The temperature of cold air leaving the pack
What 3 functions do Zone controllers have?
- Regulates the amount of trim air mixed with the cold air from the packs
- Regulates temperature by comparing actual cabin temperature with selected zone temperature set by flight crew
- Defines the temperature of the cool air and sends this info to the pack controller
Where are the air conditioning packs, valves and mixing units located on the aircraft?
In the centre wing box area
What are the 3 types of cooling device used on aircraft?
- Heat exchanger
- Vapour-cycle machine
- Air-cycle machine
What is the disadvantage of Heat exchangers?
They do not have sufficient power to cool all of the cabin air, especially on the ground
