Air Condition Flashcards
Light Aircraft Pneumatic Source
Small engine driven vacuum pump used to generate supply for instruments and de-icing boots.
What is a possible pneumatic source in a single engine piston aircraft?
Compressor pump AND Inlet manifold.
Advantage of air over hydraulics
Plentiful supply, lighter, no reservoir.
Disadvantage of Air Systems
High Pressure leaks cannot be spotted easily.
Mass Flow Controllers
Fixed mass flow.
Sends signals to spill valves to dump unwanted air if too much.
Sends signals to spill valves to close and stop air from escaping. if not enough.
Purpose of the Choke Valve
Raise the temperature of air if required.
How does the choke valve raise the temperature of the air?
Applies a back pressure to the blower.
Where does air come from?
LP stages of the HP Compressor.
Flows to the pack valve (either ON or OFF), goes to aircraft packs, cooled down and dehumidified.
Isolation Valve
Isolate Pack 1 and 2 from engines.
High Pressure Shut Off Valve
Opens relatively slowly on start-up to prevent surging.
Closes quickly to prevent ingress of fumes and smoke.
What causes over pressure?
Failure of High Pressure Shut Off Valve
Actions upon overheat?
Close bleed switch and open isolation valve to make up for lost system.
Where does the risk for carbon monoxide come from in light aircraft?
The heat exchanger.
Purpose of Air Conditioning
To supply a constant delivery of clean air to the cockpit and cabin, within a set temperature range.
What is conditioned air?
Air which is treated for pressure and temperature.
HUMIDITY is NOT controlled.
Provision of Fresh Air
1 pound per seat
0.5lbs per seat if abnormal failure.
What is the humidity at 40000ft?
1-2%
Ideal Humidity
30%
Temperature range
18-24C
Maximum Carbon Monoxide parts
1 per 20,000
Mass Flow Controller
Ensures a constant mass flow regardless of engine rpm.
Bootstrap Air Cycle System
Primary Heat Exchanger
Compressor
Secondary Heat Exchanger (Cold)
Turbine
How does the air exit the compressor?
Exits at a tangent to the periphery.
Where is the Bootstrap System most efficient at?
At high mass flows
In an air cycle machine (bootstrap system), the main water separation unit is located:
After the cooling turbine.
Ground Cooling Fan
Draws air across surface heat exchangers on the ground, or a low speeds
What are the two types of water separators?
Impingement and centrifugal
Recirculation Fans
Reduce bleed air required but drawing air from underfloor area to overhead bins cyclically.
Gasper Air
Air tapped from one of the trim air zones. Individual punkah louvres
Where do we not recycle air from?
Toilet
Galley
Trim Air
Individual zones
