13.17 Oxygen Flashcards
In aircraft to be operated at flight altitudes at which atmospheric pressure in personnel compartments will be less than 700 hPa, what is the ICAO regulation regarding what is required before flight can commence?
30 minutes at 700 – 620 hPa – Sufficient stored breathing oxygen is carried to supply all crew members and 10% of the passengers
Less than 620 hPa – Sufficient for all crew and passengers
In pressurised aircraft, intended to be operated at flight altitudes at which the atmospheric pressure is less than 376 hPa, by what value must the total number of oxygen dispensing units exceed the number of passenger and cabin crew seat?
At least 10%
What does the capability to descent dependent on?
Minimum Sector Altitude (MSA)
What is Minimum Sector Altitude determined by?
Terrain
With regards to CAA requirements, what is the provision required of first aid oxygen supply?
Must be sufficient to supply simultaneously 2% or 2 passengers, whichever is greater, wherever they are seated
At what heights would you use the following regulator restrictors in a continuous flow oxygen system:
Red
Orange
Green
Red – 8,000 to 14,000 feet
Orange – 14,000 to 22,000 feet
Green – 22,000 to 25,000 feet
Where an oxygen system utilises a manual shut off valve, when must it be ensured that it is open?
Before flight
How often are disposable masks to be used (passenger masks)?
Once only
How is it indicated that oxygen is flowing in a disposable mask?
Flow indicator shows red for no flow and green for flow
What must quick–don masks demonstrate?
Ability to be donned with one hand in 5 seconds or less
Accommodate prescription glasses
In a gaseous oxygen system, the crew and passenger oxygen systems are normally independent of each other, except in what two locations?
Common charging point
Overpressure relief facility
How will British oxygen cylinders appear?
Black with a white top hemispherical portion
How will American oxygen cylinders appear?
Green
What should be done with the oxygen cylinder manual shut off valve when a cylinder is refitted?
Wire locked open
When will the green bursting disc allow oxygen to escape to the outside of the aircraft?
Cylinder pressure rise to approximately 2800 psi
What will indicate oxygen system overpressure?
Green indicator disc has been blown out exposing red interior of the discharge fitting
or
Orange streamers released from the indicator disc
How are the supply pipes in the oxygen high pressure system identified?
Green band with the words BREATHING OXYGEN and black rectangle on a white background
What are the three methods of opening the PSU door?
Manually on the door
Manually by a switch in the cockpit
Automatically, when the cabin altitude rises by a significant amount (14,000 feet)
How is the PSU door opened where pressurised oxygen already exists as in the storage cylinder type of supply?
Compressed gas opens the door pneumatically
What are the three means by which the pneumatic electric flow regulator will initiate the supply of passenger oxygen?
At high cabin altitude (14,000 feet)
Manual activation
Electrically from a switch in the control cabin
In an electrically operated system, what happens approximately 5 seconds after the PSUs have dropped and why?
Power is removed from the solenoids which operate the strikers to open the doors
Prevent over–heating of the solenoids
At what cabin altitude is 100 percent oxygen supplied on a typical oxygen diluter demand regulator?
32,000 feet
In a chemical oxygen generator system, what are the advantages over the gaseous oxygen supply?
Saves weight (no need for storage cylinders, distribution pipes, regulators)
Improved reliability (each generator is a self–contained unit)
Reduced maintenance
No regular replenishment required
Fewer components
Replaced if they’ve been used
In a chemical oxygen generator system, when are generators not allowed to be transported by air?
Time expired
Used
How must new or unused generators intended for air transport be prepared for carriage?
In accordance with current Dangerous Goods by Air regulations
Not to be carried on passenger aircraft
With therapeutic oxygen, what is the flow rate of the LO–FLOW outlet?
2 litres per minute giving 60 minutes duration from a 120 litre cylinder
With therapeutic oxygen, what is the flow rate of the HI–FLOW outlet?
4 litres per minute giving 30 minutes duration from a 120 litre cylinder
With therapeutic oxygen, what should happen if any cylinders are used for medical purposes during a flight?
Cabin crew should make an entry in the technical or cabin log to ensure that
Cylinders are replenished prior to the next flight and
Any used masks are replaced
What is the first precaution to take account of with regards to oxygen safety precautions?
Keep oil and grease away
Why should you not mix oxygen from systems not designed for AVIATION BREATHING OXYGEN?
Medical and welding oxygen contains moisture which could freeze at altitude
Why should oxygen cylinders not be allowed to empty completely?
Condensation will occur
What is the minimum pressure of an oxygen cylinder?
200 – 300 psi
How do thermal compensators work in an oxygen charging system?
Act as a heat sink to disperse any build–up of heat from the charging process
How can the charging oxygen systems with the incorrect gas be prevented?
A left hand threaded charging valve may be used
What is the purpose of the manual shut off valve in an oxygen distribution system?
Used to prevent excessive leakage taking place while the aircraft is parked for long periods
Explain what is meant by ‘re–breather’ mask?
Defined as one that has a soft plastic reservoir bag attached at the end of it that saves one–third of a person’s exhaled air, while the rest of the air gets out via side ports that are covered with a one–way valve to allow for this
What does PSU stand for?
Passenger service unit
What pressure are aircraft oxy bottles normally charged to? (ISA)
1800 psi
List 5 things to be stencilled on an oxygen cylinder?
USE NO OIL (in red)
Manufacturers name and drawing number
Test and normal working pressure
Date of test
Capacity
Which system would utilise electrical opening of a PSU?
Chemical oxygen generators
How can a PSU be manually opened?
A small access gap exists between the PSU door and the ceiling frame to allow a thin implement to be inserted and push a support cam latch
What 2 things happen to the oxygen supply on a crew regulator when emergency is selected?
Oxygen is supplied at 100%
Positive pressure avoids any inward leakage into the mask
What is the medium, that when heated, will cause a chemical reaction in the oxygen generator?
Compressed block of sodium chlorate and iron powder
In a chemical generator, what is the pressure, temperature and duration of flow?
10 psi
10°C above ambient
15 minutes
