Aircon and Pressurisation Flashcards
What are the two types of controlling cabin temperature?
Vapour Cycle
Air cycle Machine
What does the vapour cycle do?
Process and uses the evaporation of refrigerant gas which causes temp to drop
Where is vapour cycle commonly used?
Business jets
Light turboprops
What does aircycle do?
Cooling air by expansions as it drives a turbine
Where is air bled from for aircon?
Hot compressed air is bled from high pressure end of gas turbine engine compressor
What is ram air from the ram air door used for in air con system
Cool primary and secondary heat exchangers. Results in less work by air cycle machine
Where is the water separator located?
Between the trim air valve and cabin air valve
What are the two types of pressurisation control?
Auto and Manual
What happens when max differential is reached and aircraft still climbs?
Cabin climbs at same rate as aircraft
What do outflow valves do?
Regulate outflow of cabin air to control cabin pressure at desirable and safe levels
What sort of signals do outflow valves respond to?
Electrical or pneumatic
How is the outflow valve opened and closed?
Spring loaded to closed
Low pressure vacuum pumps open it
What happens if cabin pressure exceeds a certain predetemined value?
Outflow valve will open, cabin air flows overboard
What are negative relief valves?
Cabin air pressure inside is greater than outside air pressure.
Spring loaded doors, valve that opens to dump excess pressure overboard
When do negative relief valves open?
Negative pressure reaches 0.5psi
