11.15 Oxygen

Question 1

What is the main purpose of having an oxygen system on board an aircraft?
A) To cool avionics systems
B) To ensure oxygen supply in emergencies
C) To pressurise hydraulic systems

Answer 1

B) To ensure oxygen supply in emergencies

Question 2

According to EU-OPS 1.760, what must a pressurised aircraft above 25,000 ft carry?
A) Fire extinguishers in all compartments
B) Oxygen masks for the flight crew only
C) A supply of undiluted oxygen for passengers who may need it

Answer 2

C) A supply of undiluted oxygen for passengers who may need it

Question 3

What is the metric equivalent of 25,000 feet?
A) 2500 m
B) 7620 m
C) 4300 m

Answer 3

B) 7620 m

Question 4

At what maximum altitude is the cabin altitude maintained by the pressurisation system?
A) 3048 m
B) 2440 m
C) 9144 m

Answer 4

B) 2440 m

Question 5

What happens to the density of air and oxygen availability as altitude increases?
A) Both increase
B) Density increases, but oxygen stays the same
C) Both decrease

Answer 5

C) Both decrease

Question 6

What is the oxygen percentage at 10,000 ft?
A) 20.1%
B) 14.3%
C) 11.8%

Answer 6

B) 14.3%

Question 7

What condition results from insufficient oxygen in the body?
A) Hypoxia
B) Hyperthermia
C) Hypertension

Answer 7

A) Hypoxia

Question 8

Which of the following methods is used to counteract the negative effects of reduced oxygen pressure at altitude?
A) Lowering cabin humidity
B) Increasing airspeed
C) Increasing oxygen pressure or concentration

Answer 8

C) Increasing oxygen pressure or concentration

Question 9

Why must aircraft cabins be pressurised at high altitudes?
A) To maintain hydraulic pressure
B) To prevent icing
C) To increase the pressure of oxygen

Answer 9

C) To increase the pressure of oxygen

Question 10

What color are cylinders containing pure or nearly pure gaseous oxygen typically painted?
A) Yellow
B) Green
C) Red

Answer 10

B) Green

Question 11

Which type of oxygen is suitable for use in aircraft?
A) Medical oxygen
B) Technical oxygen
C) Aviator’s breathing oxygen

Answer 11

C) Aviator’s breathing oxygen

Question 12

Why is medical oxygen not used on aircraft?
A) It is too expensive
B) It contains water droplets that freeze
C) It reacts with hydraulic fluid

Answer 12

B) It contains water droplets that freeze

Question 13

Why is technical oxygen unsuitable for aircraft use?
A) It is stored at low pressure
B) It is too dry
C) It is contaminated

Answer 13

C) It is contaminated

Question 14

What is a key safety rule when working with oxygen systems?
A) Always perform power-on checks
B) Work in enclosed spaces
C) Keep oxygen away from petroleum products

Answer 14

C) Keep oxygen away from petroleum products

Question 15

What should be avoided when working on an aircraft oxygen system?
A) Cleaning tools
B) Using power-on checks
C) Cordon off the area

Answer 15

B) Using power-on checks

Question 16

What is a good maintenance practice for oxygen systems?
A) Use tools covered in oil
B) Work indoors near heaters
C) Use clean, grease-free, dedicated tools

Answer 16

C) Use clean, grease-free, dedicated tools

Question 17

How far must smoking and open flames be kept from oxygen work areas?
A) 5 m (15 ft)
B) 10 m (33 ft)
C) 15 m (50 ft)

Answer 17

C) 15 m (50 ft)

Question 18

Where should oxygen cylinders be stored?
A) Near fuel tanks
B) In a designated cool, ventilated area
C) Next to the cockpit

Answer 18

B) In a designated cool, ventilated area

Question 19

Where are the high-pressure oxygen bottles for the flight crew system typically located?
A) Flight deck overhead
B) Near passenger seats
C) In the avionics or cargo compartment

Answer 19

C) In the avionics or cargo compartment

Question 20

What component controls the distribution pressure in the flight crew oxygen system?
A) Flow sensor
B) Pressure reducing valve (PRV)
C) Humidity regulator

Answer 20

B) Pressure reducing valve (PRV)

Question 21

What system supplies oxygen only to the cockpit crew?
A) Cabin system
B) Passenger system
C) Crew oxygen system

Answer 21

C) Crew oxygen system

Question 22

What triggers the deployment of passenger oxygen masks?
A) Loss of hydraulic pressure
B) Altitude above 4300 m (14,000 ft)
C) Manual command by flight crew

Answer 22

B) Altitude above 4300 m (14,000 ft)

Question 23

Where must passenger oxygen masks be located?
A) At cockpit entrances only
B) At each passenger seat, lavatory, and attendant station
C) In overhead bins

Answer 23

B) At each passenger seat, lavatory, and attendant station

Question 24

What colour are most high-pressure oxygen cylinders typically painted?
A) Yellow
B) Green
C) Red

Answer 24

B) Green

Question 25

Where are oxygen bottles commonly stored on an aircraft? A) In the cabin near the passenger seats B) In the wing compartments C) In the cargo compartment or Main Equipment Centre (MEC)

Answer 25

C) In the cargo compartment or Main Equipment Centre (MEC)

Question 26

What is the typical pressure rating for traditional steel oxygen bottles? A) 1000 – 1200 psi B) 1800 – 1850 psi C) 3000 – 3500 psi

Answer 26

B) 1800 – 1850 psi

Question 27

What component on an oxygen bottle prevents damage due to overpressure? A) Relief valve B) Frangible disc C) Filler valve

Answer 27

B) Frangible disc

Question 28

What indicates which oxygen bottle has discharged through the overboard discharge line? A) A red warning light B) The smell of escaping gas C) The pressure gauge on each bottle

Answer 28

C) The pressure gauge on each bottle

Question 29

What must be done if the thermal compensator’s B-nuts are disconnected? A) Retighten the nuts B) Replace the entire unit C) Leave it disconnected

Answer 29

B) Replace the entire unit

Question 30

What material is often used for high-pressure oxygen lines in aircraft? A) Copper B) Stainless steel C) Plastic

Answer 30

B) Stainless steel

Question 31

What type of thread is used on tubing-to-component fittings in oxygen systems? A) Reverse threads B) Internal threads C) External tapered pipe threads

Answer 31

C) External tapered pipe threads

Question 32

What do the green bands and printed text on oxygen tubing identification tape indicate? A) Fuel line B) Hydraulic line C) Breathing oxygen

Answer 32

C) Breathing oxygen

Question 33

How many types of valves are commonly found in high-pressure oxygen systems? A) Three B) Five C) Seven

Answer 33

B) Five

Question 34

What is the primary purpose of portable oxygen cylinders on an aircraft? A) Fuel combustion B) Routine passenger use C) Emergency and first aid use

Answer 34

C) Emergency and first aid use

Question 35

What protects the user from smoke and noxious gases and is often vacuum packed with a serviceability indicator? A) Oxygen cannula B) Smoke hood C) Emergency air bottle

Answer 35

B) Smoke hood

Question 36

What happens to a smoke hood when its oxygen supply ends? A) It expands B) It turns off C) It begins to deflate

Answer 36

C) It begins to deflate

Question 37

What must be done before charging any oxygen system? A) Check the aircraft colour code B) Fill the cylinder fully C) Consult the Aircraft Maintenance Manual (AMM)

Answer 37

C) Consult the Aircraft Maintenance Manual (AMM)

Question 38

What is used to purge air from the hose before filling an oxygen system? A) Nitrogen gas B) Purge valve C) The refilling hose itself

Answer 38

C) The refilling hose itself

Question 39

What minimum pressure must a cylinder have to be considered refillable? A) 100 psi B) 50 psi C) 10 psi

Answer 39

B) 50 psi

Question 40

What is used to detect leaks in an oxygen system? A) Water B) Alcohol C) Oxygen-safe leak check fluid

Answer 40

C) Oxygen-safe leak check fluid

Question 41

What type of oxygen system is most commonly used in light aircraft? A) Built-in continuous-flow system B) Chemical oxygen system C) Portable oxygen cylinder with a mask and regulator

Answer 41

C) Portable oxygen cylinder with a mask and regulator

Question 42

In larger portable oxygen systems, how many people can typically share the system? A) 1-2 B) 2-4 C) 4-6

Answer 42

B) 2-4

Question 43

In built-in oxygen systems, who typically controls the central regulator? A) Passengers B) Flight attendants C) Flight crew

Answer 43

C) Flight crew

Question 44

How is oxygen stored in aviation oxygen systems? A) As a liquid B) As a gas at atmospheric temperature in high-pressure cylinders C) As a solid in low-pressure containers

Answer 44

B) As a gas at atmospheric temperature in high-pressure cylinders

Question 45

What are the two main types of oxygen regulators used in aviation? A) Liquid-flow and gas-flow B) Chemical-flow and electric-flow C) Continuous-flow and demand-flow

Answer 45

C) Continuous-flow and demand-flow

Question 46

What happens in a continuous-flow system when the user is not inhaling? A) Oxygen flow stops B) Oxygen flows continuously C) Oxygen is redirected to another user

Answer 46

B) Oxygen flows continuously

Question 47

What component is used in some continuous-flow systems to fine-tune oxygen delivery? A) Emergency switch B) Pressure switch C) Adjustable flow indicator

Answer 47

C) Adjustable flow indicator

Question 48

What feature of rebreather cannulas and bags helps reduce oxygen waste? A) Built-in filters B) Capturing exhaled oxygen for reuse C) Mixing cabin air

Answer 48

B) Capturing exhaled oxygen for reuse

Question 49

In a demand-flow system, when is oxygen delivered? A) Continuously B) Only when the user inhales C) Only when the system is reset

Answer 49

B) Only when the user inhales

Question 50

What types of demand regulators exist? A) Chemical and thermal B) High-pressure and low-pressure C) Diluter-demand and pressure-demand

Answer 50

C) Diluter-demand and pressure-demand

Question 51

What special function does a diluter-demand regulator provide? A) Oxygen flows regardless of breathing B) Allows manual selection of 100% oxygen C) Built-in chemical oxygen generator

Answer 51

B) Allows manual selection of 100% oxygen

Question 52

What is the key difference in pressure-demand systems compared to diluter-demand systems? A) Continuous oxygen flow B) Oxygen is delivered under higher pressure C) Use of chemical oxygen sources

Answer 52

B) Oxygen is delivered under higher pressure

Question 53

How is oxygen pressure reduced in a two-step regulation process? A) Using solenoids and switches B) Using two types of masks C) By a pressure reducer then a regulator

Answer 53

C) By a pressure reducer then a regulator

Question 54

In Airbus aircraft, what must the crew do to receive oxygen? A) Remove a mask B) Pull a lanyard C) Operate a switch on the flight deck

Answer 54

C) Operate a switch on the flight deck

Question 55

What happens when a crew mask is removed from its stowage box? A) It ignites a chemical reaction B) A supply valve opens and oxygen flows C) The system shuts off

Answer 55

B) A supply valve opens and oxygen flows

Question 56

What does pressing the red grips on a crew oxygen mask do? A) Activates the microphone B) Inflates the harness for donning C) Releases the regulator from the mask

Answer 56

B) Inflates the harness for donning

Question 57

Where are passenger oxygen masks stored on large aircraft? A) Under the seat B) In sidewall compartments C) In the Passenger Service Unit (PSU)

Answer 57

C) In the Passenger Service Unit (PSU)

Question 58

How is oxygen flow to a passenger mask activated? A) Manually by flight attendants B) Automatically by altitude sensors C) By pulling the mask, which activates a lanyard

Answer 58

C) By pulling the mask, which activates a lanyard

Question 59

What ensures extra oxygen masks are available in a row of seats? A) A storage locker B) An additional mask per row C) Built-in rebreather bags

Answer 59

B) An additional mask per row

Question 60

What tool allows maintenance to release individual PSU boxes without deploying the entire system? A) Safety lever B) Oxygen override switch C) Restraint/release tool

Answer 60

C) Restraint/release tool

Question 61

What are the two types of passenger oxygen supply systems? A) Electrical and pneumatic B) Chemical and gaseous C) Manual and automatic

Answer 61

B) Chemical and gaseous

Question 62

What triggers oxygen flow in a chemical oxygen system? A) Battery power B) Pulling the mask to start a chemical reaction C) Opening the PSU door

Answer 62

B) Pulling the mask to start a chemical reaction

Question 63

What chemical is primarily used in chemical oxygen generators? A) Lithium oxide B) Barium chloride C) Sodium chlorate (NaClO₂)

Answer 63

C) Sodium chlorate (NaClO₂)

Question 64

What does barium peroxide do in a chemical oxygen generator? A) Initiates the reaction B) Absorbs chlorine byproducts C) Cools the reaction

Answer 64

B) Absorbs chlorine byproducts

Question 65

What does an On Board Oxygen Generating System (OBOGS) use to separate oxygen? A) Centrifugal force B) Molecular sieve C) Sodium chlorate

Answer 65

B) Molecular sieve

Question 66

What system uses Flow Control Units (FCUs)? A) Chemical oxygen system B) Gaseous passenger oxygen system C) OBOGS

Answer 66

B) Gaseous passenger oxygen system

Question 67

How do FCUs assist in PSU door opening? A) They ignite oxygen candles B) They send a pressure push C) They activate solenoids

Answer 67

B) They send a pressure push

Question 68

In the gaseous system, when does oxygen begin to flow to the passenger mask? A) When the PSU door opens B) When a flow switch is flipped C) When the lanyard is pulled

Answer 68

C) When the lanyard is pulled

Question 69

What is the purpose of a blowout disc in an aircraft oxygen system? A) To increase oxygen flow during emergencies B) To signal that system pressure is too low C) To indicate if the relief valve has released excess pressure

Answer 69

C) To indicate if the relief valve has released excess pressure

Question 70

Where is the blowout disc typically located on an aircraft? A) In the cockpit panel B) On the fuselage skin C) Inside the oxygen bottle compartment

Answer 70

B) On the fuselage skin

Question 71

What color is most commonly used for oxygen system blowout discs? A) Red B) Green C) Yellow

Answer 71

B) Green

Question 72

What is the primary function of a flow indicator in an oxygen system? A) To control the oxygen concentration B) To show whether oxygen is flowing C) To regulate bottle pressure

Answer 72

B) To show whether oxygen is flowing

Question 73

Which of the following components is moved by the oxygen stream to show system functionality? A) Blowout disc B) Pulse oximeter C) Flow indicator

Answer 73

C) Flow indicator

Question 74

What type of device can flight crew in smaller aircraft use to monitor their oxygen saturation levels? A) Barometer B) Pulse-type oximeter C) Pressure gauge

Answer 74

B) Pulse-type oximeter

Question 75

What does a pulse oximeter measure in the context of oxygen system usage? A) Cabin pressure B) Blood oxygen saturation level C) Flow rate from the bottle

Answer 75

B) Blood oxygen saturation level