Oxygen System Flashcards
In broad terms, describe how the Oxygen system operates.
Air is bled from the engine and cooled down. The air is dried out and fed into the OBOGS machine. This machine used a zeolite sieve to concentrate oxygen. This is then fed to the pilots via a plenum, to keep the flow smooth.
What does OBOGS stand for?
On Board Oxygen Generation System
How many minutes of oxygen does the emergency oxygen system provide?
10 minutes
How is the emergency oxygen system activated?
By pulling the green ring on the left of the seat up aft. Left for life.
If you start coughing, and find white dust in your oxygen mask, what is the probable cause and what should you do?
Probable cause: The zeolite sieve that concentrates the oxygen has broken down.
Actions: Activate emergency oxygen system and descend below 10,000ft within 10 mins.
What engine stage is air bled from for the Environmental Control System?
Stage 3
The Bleed Air Inflow switch controls the position of the Bleed Air Inflow Valve. Describe the position of the valve when the switch is in the following positions:
A) OFF
B) NORM
C) HI
A) Closed
B) Mid-Open
C) Fully Open
When the air conditioning is ON, above what height will the Bleed Air Inflow valve automatically close?
7500ft
What does turning DEFOG ON do?
It will:
Open the DEFOG Valve
Set the Inflow Valve to high
Turns on the Air Conditioning
What effect on performance will turning DEFOG ON have?
Rate of climb will reduce by 4-7%.
ITT will increase.
When the DEFOG valve is turned Off, how long can it take for the DEFOG valve to close?
Up to 40 seconds.
What happens if the OBOGS Duct temperature goes above 148 degrees C?
The OBOGS TEMP caption will appear on the EICAS.
The RAM AIR FLOW switch controls the position of the Fresh Air Valve. Describe the position of the valve when the switch is in the following positions:
A) OFF
B) NORM
C) HI
A) Closed
B) Mid-Open
C) Fully Open
Above what height does the Fresh Air Valve close automatically? Why?
8000ft. To allow for cockpit pressurisation.
You want to isolate airflow from the engine to the cockpit, but without using the firewall cut off lever. What switches must you set to Off.
Bleed Air Inflow.
Defog.
