Oxygen and pressurization systems

Question 1

What are the 4 types of oxygen mask used with supplemental oxygen?

Answer 1

Cannula
Re-breather
Diluter-demand mask
Pressure-demand mask

Question 2

What are the 4 types of oxygen supply?

Answer 2

Gaseous
Liquid
Solid
Mechanical extrication

Question 3

How is gaseous oxygen supplied?

Answer 3

Stored in cylinders around 2000PSI

Question 4

How is liquid oxygen (LOX) supplied?

Answer 4

Kept cool (-180 F0, expands 862:1

Question 5

How is solid chemical oxygen supplied?

Answer 5

“Candle” of sodium chlorate, chemical reactions heat and breathable oxygen

Question 6

How is Mechanical extraction oxygen supplied?

Answer 6

Uses molecular sieve to trap all gas molecules except oxygen from compressor bleed air

Question 7

What is the molecular makeup of the atmosphere?

Answer 7

21% oxygen, 78% nitrogen, and 1% miscellaneous

Question 8

What colors can oxygen cylinders be and what two markings must be on them?

Answer 8

Normally green (high pressure); yellow (low pressure)

Marked with hydro-static date and must be marked “aviators breathing oxygen

Question 9

Explain the differences between the continuous flow and demand type oxygen systems.

Answer 9

Continuous flow: turned on by pilots or an altitude sensing anderoid w/pressure regulator. Oxygen flows continuously to the mask when turned on

Demand: Uses pressure regulators at each mask to allow gas to flow only when the user inhales

Question 10

What is hypoxia?

Answer 10

A physiological condition caused by high altitude without sufficient oxygen

Question 11

How does hypoxia affect people?

Answer 11

Impairs vision and judgment, gives a headache, increases breathing rate, eventually unconsciousness and death.

Question 12

What tools can be used while servicing oxygen systems?

Answer 12

Clean tools. Dedicated clean tools clean of greases, fuel, and oil

Question 13

What is a hydrostatic test and why is it important?

Answer 13

Oxygen bottle test

Bottles filled with water and pressurized 5/3 working pressure to test integrity of the bottle

Question 14

Name 5 things to check for when servicing an oxygen bottle?

Answer 14

Hydrostatic date (stamped near neck)
Bottle pressure ( do not service if under 50PSI)
Inspect for damage
Filled with “aviators breathing oxygen”
Use a pressure-temperature chart and fill slowly
Service from the lowest bottle first

Question 15

When would you need to purge an oxygen system?

Answer 15

If the system is low or they system is contaminated

Question 16

Name advantages for aircraft pressurized and flying at high altitudes

Answer 16

Less drag
Less turbulence
Avoid bad weather
Reduced air traffic

Question 17

Name disadvantages for aircraft being pressurized and flying at high altitudes

Answer 17

Cabin has to be pressurized=heavier
Costly and requires more maintenance and training
Pressurization failures
Shorter life cycle due to strain on aircraft

Question 18

What is cabin differential pressure?

Answer 18

Difference between the cabin atmospheric pressure and the outside atmospheric pressure

Question 19

What are 3 common sources that provide pressurized air to the reciprocating engines?

Answer 19

Superchargers
Turbochargers
Engine drive compressors

Question 20

What is the advantage to the crew of using engine driven compressors over superchargers or turbo chargers?

Answer 20

Avoids contamination from either the fuel intake system or the exhaust system

Question 21

What are three sources of pressurization for turboprops?

Answer 21

Piston type pump
Root blower
Jet pumps

Question 22

What are 3 sources of pressurization for full jet aircraft?

Answer 22

Engine bleed air
Turbo-compressors
Jet pumps

Question 23

Three modes of pressurization

Answer 23

Unpressurized
Isobaric
Constant differential

Question 24

What is unpressurized mode?

Answer 24

Cabin pressure is the same as ambient air pressure (outflow valve fully open)

Question 25

What is isobaric mode?

Answer 25

The pressure controller closes and opens the outflow valve to maintain a set cabin altitude

Question 26

What is constant-differential mode?

Answer 26

The ratio between internal and external air pressure. The pressure controller will maintain a constant pressure differential as altitude changes

Question 27

Three modes of operation?

Answer 27

Auto
Alternate
Manual

Question 28

Explain auto

Answer 28

Normal mode providing automatic control

Question 29

Explain alternate

Answer 29

Standby mode also providing automatic control but usually w/ different inputs and a standby controller and standby outflow valve operation

Question 30

Explain Manual

Answer 30

In case auto and standby fail, allowing crew to directly position the outflow valve through pneumatic or electric control

Question 31

What is the purpose of the outflow valve?

Answer 31

To let air out of the pressurized vessel, keeping the cabin pressure constant at the correct pressure

Question 32

What is the difference between the negative pressure relief valve and the safety valve?

Answer 32

Negative pressure relief valve: makes sure that the inside cabin pressure is always equal to or greater than the outside air pressure. Valve will open if outside air pressure increases above cabin pressure to allow outside air into the cabin to balance the pressure

Question 33

What mode of operation would an A&P mechanic use to perform a pressure check and why?

Answer 33

The manual mode would be used so that the outflow valve would close and pressurize on the ground

Question 34

What is a standard day condition?

Answer 34

59F
14.69PSI

Question 35

Explain partial pressure?

Answer 35

The percentage of the total pressure of a mixture of gases produced by each of the individual gases in the mixture

Question 36

At what altitude do humans need supplemental oxygen?

Answer 36

10,000ft

Question 37

What is humidity?

Answer 37

The measure of water vapor in the air

Question 38

What is cabin pressure differential formula?

Answer 38

Cabin pressure-Ambient pressure=differential pressure