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What percentage of air is oxygen?
As air temperature increases , density...?
What condition does the human body encounter when it becomes deprived of required oxygen?
Result of incomplete burning of fuels ?colorless odorless and tasteless
What are the 4 types of oxygen supplementation?
- Compressed gas
- Liquid oxygen
- Solid state
- Mechanically separated
Compressed O2 is stored in what color cylinders?
Typical compressed O2 bottles are pressured to what PSI?
1800 - 2400 psi
What is one advantage and one disadvantage of compressed gas O2
- adv: ease of handling
- dis: Weight
What is the #1 benefit on liquid oxygen?
Economical in space and weight
One disadvantage of O2 generators?
- Single use
- gets very hot when in use
what are 3 types of O2 storage bottles?
O2 cylenders must be tested at what pressure?
5/3 of their working pressure
composite bottles must be tested every... years?
steel bottles must be teseted every .... years?
Cylenders must be taken out of use after how many year2?
What is critical about checking on exuast shroud type heaters ?
leak checking around welded studs , carbon monoxide poisoning
What are the welded studs for on exuast shroud type heaters?
Increase surface area for more effective heating
When are electric resistance type heaters primarily used?
supplemental heat, usually on the ground
What is installed on electric resistance type heaters?
safety switch to turn them off in case of fan failure
What heating is primarily used for large transport catagory aircraft?
Medium twin engine aircraft are usually heated with what king of heat?
Combustion type heaters (Janitrol)
On a Combustion heater , what 3 switches control the fuel soleniod?
- pressure switchs
What does the duct limit switch do on a combustion heater?
shuts off fuel when there is not enough airflow to remove heat from the duct
What does the overheat switch do on a combustion type heater?
Set higher than duct limit switch but below fire temp, closes fuel , combustion air and ignition
The refrigerant used in most vapor cycle aircraft cooling systems?
R12 , freon 12
In a vapor cycle cooling system , where is the heat removed from the air?
Vapor cycle cooling system, as the refrigerant changes state , what happens to the temperature?
temperature of the coolant remains the same
What happens to water that enters the system while servicing ?(vapor cycle a/c)
desicant in the receiver/dryer catches it
what is the boiling point on freon 12?
where can you find the correct lubricant for the A/c pump?
On a belt driven freon compressor , how is the component cycled on and off?
what component controls the amount of coolant that is sprayed into the evaporator? vapor cycle a/c
thermal expansion valve
what is the purpose of the thermal expansion valve? vapor cycle a/c
to meter the correct amount of coolant into the evaporator
What 2 components in a vapor cycle a/c system seperate the high and low sides?
- thermal expansion valve
what is the pressure indicator travel for the low side gauge? vapor cycle a/c
-60 psi to 60 psi
how do you check a vapor cycle a/c system for leaks?
- soapy water
- electronic sniffer
how are the hoses for the vapor cycle a/c manifold easily identified?
- by color
how is refrigerant measured?
why must a vapor cycle a/c system be evacuated before refilling?
to remove any water vapor in the air that may lead to icing in the a/c system
how is full refrigerant seen in an a/c system ?
no more bubbles in the sight glass
why is it critical to aviod getting liqiud refigerant in the low side while filling?
it will enter the compressor pump and hydraulicly lock it .. causing major damage
what must be done before checking compressor oil level in the a/c vapor system?
run a/c for 15 minutes
what is latent heat?
the state changes but temp stays constant
what is superheat?
temperature created by a gas above its boiling pointof the base liquid
what is the purpose of the landing gear switch in the janitrol heater circuit?
to turn on the fans to supply air on the ground, because they cannot rely on ram air anymore
what TC document requires us to check muff heaters for leaks regularly?
what is the purpose of a "pack" valve on a turbine ACM cooling system?
to take or shut bleed air from the engines
where is most of the heat energy removed from the ACM system?
the expansion turbine in ACM
Why is there a water seperator on an ACM?
prevent icing in system
what is the purpose of the temp control valve that bypasses the air around compressor and turbine of ACM?
controls cabin temperature
How do you do a pressure decay test on acombustion heater liner?
plug it off, pressure to 6 psi, wait 45 seconds and check for 1 psi remaining
why is an ACM often called a pack?
Boeing calls it "Pnuematic Air Conditioning Kit"
what are the 2 air pressures in combustion heater?
- ventilation air and combustion air
- ventilation must always be higher to prevent CO poisoning
How often do you do a pressure decay test on a janitrol?
500 hours or seasonally
PACK fans are driven 4 ways?
- Mechanicly linked
- bleed air driven
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