Answers - Cabin Environmental | Aircraft Systems

Answers - Cabin Environmental


1. Colorless, odorless, tasteless
2. Aviator Breathing Oxygen
3. 50, water vapor
4. Demand‐flow
5. Diluter‐demand, pressure‐demand
6. Moisture
7. 8,000 ft, cruising altitude
8. Pressurization, depressurization
9. Supercharger, turbocharger, engine driven compressor
10. Bleed air
11. Isobaric, differential
12. Cabin altitude, rate of change, barometric pressure
13. Outflow valve
14. Electrically, cabin pressure controller
15, Over pressurization
16. Negative relief valves
17. Vapor cycle, air cycle
18. Engine compressor, APU
19. Refrigeration turbine unit, air cycle machine
20. Thermistors, resistance
21. Liquid, vapor
22. Receiver dryer
23. Copper, aluminum
24. Exhaust gases
25. Cleaning filters, spark plug


1. true
2. false; they are painted green.
3. true
4. false; indicates that the pressure relief valve has opened and this should be investigated.
5. true
6. true
7. false; below 8,000
8. true
9. false; turbochargers are the most common.
10. false; turbochargers are driven by exhaust gases.
11. true
12. false; differential control mode of a cabin pressurization system controls pressure to maintain a constant pressure between the air outside the cabin and the ambient air.
13. true
14. false; prevent cabin over pressurization.
15. true
16. true
17. false; a swirling motion will separate the water droplets.
18. true
19. false; It is an closed system
20. false; R134‐A has replaced R12
21. true
22. false. should feel cool.
23. true
24. false; use a exhaust shroud heating system.
25. false; drawn from an aircraft fuel tank.


1. outflow valve

2. Bleed air from the turbine‐engine compressor

3. The cabin pressure controller.

4. Gasoline combustion heater, electric heater, and exhaust shroud heat exchanger.

5. carry the heat where it is needed

6. expansion turbine, air‐to‐air heat exchangers, water separator, and various temperature control valves.

7. The compressed air turns a turbine, and it undergoes a pressure and temperature drop.

8. moist air passes through a fiberglass bag that condenses the moisture in droplets, vanes swirl the air and droplets are collected and drained.

9. The compressor pressurizes low pressure vapor into high pressure vapor. The condenser cools the high pressure vapor with outside air and turns it into a high pressure liquid. At the expansion valve the high pressure liquid changes into a low pressure liquid. In evaporator the low pressure liquid absorb s cabin heat and change into a low pressure vapor and returns to the receiver dryer where the process is repeated again.

10. When the pack valve opens hot high pressure bleed air flows to air mix valve. Depending on temperature a certain amount of this bleed air travels to the mixing chamber and the rest flows to the primary heat exchanger to be cooled. The bleed air will travel through a second mixing valve and enters the compressor of the air cycle machine. The pressure and temperature of the bleed air increases. The bleed air will flow through the secondary heat exchanger where its temperature is lowered by ambient air. After the secondary heat exchanger the air enters the aircycle machine. Here the air temperature lowers because energy in the air drives the turbine which in turn drives the compressor. The shape of the turbine blades expand the air which lowers in pressure and temperature. The air that leaves the air cycle machine flows through the water separator where moisture is removed. When the sensor at the water separator senses 35 degrees the anti‐ice control valve opens to allow warmer air to mix with the air leaving the air cycle machine. The air that leaves the water separator will flow to the mixing chamber where it is mixed with hot bleed air. Temperature control is realized by positioning the two mixing valves so that the desired temperature is achieved.

11. A receiver dryer, evaporator, compressor, condenser, and expansion valve.

12. oxygen flows from a charged cylinder through a high pressure line to a reducing valve and to mask outlets.

13. system must be purged to remove moisture

14. dry nitrogen, dry air, or oxygen

15. aviators' breathing oxygen

16. provide lubrication and prevent compressor failure

17. use oil free tools, clothing, hands, adequate eye protection

18. turbocharger, supercharger, engine driven compressor

19. small amount of LOX can be converted to an enormous amount of gaseous oxygen, thus needing little storage space.

20. cabin altitude, rate of change, and barometric correction and pressurization mode