Air Conditioning & Pressurization Flashcards
How does ground air reach the system?
Connected thru the left air conditioning manifold and goes into the mix manifold then distributed.
Does ground air go thru the packs?
No
What is the function of the compartment temp control switches and how do they accomplish it?
Used to control temp in the associated zones. The knob adjusts the trim air valves for the associated zones to provide the desired temp.
When does the compartment temperature inop light come on?
- Duct temp over heat
- Fault in the temp control system
- Trim air selected off
- Associated temp control switch selected off
What does the C and W on the trim air valve control mean and what are the associated valve position?
C - cool, valve closed
W - warm, valve open
What are the min and max ranges on the automatic temp controller?
C - 65f
W - 85f
65 to 85 are the ranges
Do you have manual trim air control for fwd and aft cabin?
No.
Do you have manual control of trim air for cockpit? If so how do you accomplish that?
Yes. By selecting M on the controller and putting the switch to C or W will modulate the cockpit trim air valve
Is there a dedicated switch to close the cockpit trim air valve?
No unlike the fwd and aft cabin, there is no dedicated off position for the trim air valves. However you can still close it manually using the M mode on the controller
Which single valve is the trim air switch controlling?
The trim air regulating valve
Do we have recirc fans?
No
What is the function of the pack reset switch?
Reset the pack if it has cooled down
What does the pack inop light mean?
Pack overheat or a fault in the automatic control system.
Pack off light
Pack valve is closed
What temp will stby N set on the pack control knob?
75f
What temp will stby W set on the pack control knob?
STBY W sets the pack so the outlet temperature is controlled by ram air flowing across the pack heat exchangers. This pro-duces the warmest output possible without causing an internal overheat
Will the pack valve open or close when you set the knob to auto or manual?
The pack valve arms open.
How is the pack valve operated?
Electro Pneumatic.
Describe the PACK HIGH FLOW operation?
Ground operation whenever the APU or ground source is supplying air for air conditioning (both packs increase).
- Flight if one pack is off or inoperative.
The pack high flow system is inhibited when:
1. Wing anti-ice is on and only one engine is supplying bleed air.
- An engine is inoperative.
- Flaps are not in the up position.
- CARGO FIRE/DEPR switch is pushed
Describe PACK LOW FLOW ops?
- When the CARGO FIRE/DEPRESS switch is pushed, with both packs operating and in the same mode, the right pack is commanded OFF, and the left pack goes to low flow.
- For single pack operations, the operating pack goes to low flow.
What happens to the thrust limit of an engine in pack high flow ops?
When a pack is operating in high flow the displayed Maximum Thrust limit for the associated engine is automatically reduced.
What happens if the automatic pack control function fails?
The pack temp control valves freeze in the last position and the pack has to be run in the stby modes.
What is automatically done to the packs if the inop light comes on because of an overheat of the air leaving the packs?
The pack is automatically set and locked to maximum cooling if the INOP light illuminates because of an overheat in the air as it leaves the pack. After cooling, the pack can be reset for automatic or standby operation by pushing the PACK RESET Switch
What are some reason why a PACK OFF light may come on?
- Pack control selector off
- Pack trip has occured
- Pack has lost air supply
What happens to pack valve if you get a PACK OFF light?
Means pack valve is closed
What will the packs do if you turn the trim air off?
air conditioning packs default to a 75° F cabin temperature
What temp range will the fwd and aft cabin controllers be able to maintain with the main deck temp selector in the ANIMAL/NORMAL mode?
65f to 85f
What temp range will the fwd and aft cabin controllers be able to maintain with the main deck temp selector in the PERISHABLE mode?
35f to 71f
How many heaters do we have for the foot and shoulder heat for the pilots?
Each system has 2 heaters. One for foot and one for shoulder. The f/o and captain has independent systems.
Is the crew heat operable during ground ops?
No
How many pressurization controllers do we have?
2
What happens if one pressure controller fails?
The other one automatically takes control
Is the automatic pressurization controller ac or dc?
Ac
Is the manual pressurization controller ac or dc?
Dc - standby dc bus
What 2 modes of pressurization are available?
2.. Auto and manual
How many outflow valves do we have?
1
index mark on the pressurization control indicates what?
Pressurization rate
500 for climb and 300 for descent
Can you change the rate of airplane pressurization setting?
Yes.. Using the cabin altitude auto rate control dial
Does the auto pressure controllers have separate motors for controlling te outflow valve?
Yes. They are independent systems
When does the airplane enter cruise mode?
The pressurization cruise mode is established when the airplane altitude remains constant for one minute.
When does the airplane enter descent mode?
When the airplane descends more than 500 feet in the cruise mode, the cabin enters a descent mode.
How does the airplane get back into the climb mode after an intermediate level off for more than a minute?
Once the airplane climbs more than 500 ft it goes back into the normal climb schedule
What does the outflow valve do after landing?
It opens to slowly depressurize the airplane
What test does the pressurization system do after each landing?
A self test of the alternate controller
What does the cabin auto inop light mean?
CABIN AUTO INOP, indicates both Auto 1 and Auto 2 cabin altitude controllers are inoperative
What happens to the outflow valve when both auto controllers fail?
Freezes in the last position until manual control is taken
When does the red cabin altitude light illuminate?
Cabin altitude above 10000ft
When does the red cabin altitude light extinguish?
Cabin altitude back below 8500ft
In auto mode, what does the outflow valve do once you go above 11000 ft cabin altitude?
In automatic control, if the cabin altitude climbs above 11,000 feet, the outflow valve is automati-cally closed by an aneroid switch. Manual control is still available through the manual selector. When cabin altitude descends below 9,500 feet, the aneroid switches open and the outflow valve circuits are restored.
What does the manifold interconnect valve do?
The manifold interconnect valve supplies conditioned air or E/E cooling air to the flight deck instruments based on the temperature of pack air, when one or both packs are operating in flight.
What does the smoke/override valve do?
smoke/override valve allows cabin pressurization to supply cooling flow or exhaust smoke from the forward E/E as air is vented overboard
How many fans normally supply cooling air for avianics?
2
Both work on the ground and only 1 in the air
What happens if one avionics cooling fan goes out?
The other one automatically takes over
Which are the 2 fans for equipment cooling?
Supply fan and exhaust fan
What mode do you select if smoke is detected in the equipment cooling system?
Override
When will the NO COOLING light illuminate?
If no airflow is detected thru the e&e bay after 1 minute of selecting override mode
What happens to the supply and exhaust fans when u select the ovrd mode?
They are shutoff
Where does the air for equipment and avionics cooling come from when you select the ovrd mode?
The conditioning manifold valve opens and you get conditioned air
In auto mode in flight, which fan is normally running?
Exhaust fan
In stby mode in flight, which fan is normally running?
Supply fan
In ovrd mode, which is the only valve that will be open?
The smoke/ovrd valve
Will the ground crew horn sound if ovrd is selected on the ground?
Yes
When does the valve light come on?
When any of the inboard or overboard valves are not in the signaled position.
What happens to the inboard and overboard valves when you select stby?
They go to the inboard configuration. The inboard opens and overboard closes. The valve light goes away
What does the OVRHT light mean?
The OVHT light and the EICAS advisory message, FWD EQPT OVHT, indicate high temperature or lack of airflow in the equipment cooling system
How many cooling fans are there for the aft equipment bay?
- One runs continuously. When one fails the other take over.
What happens to the aft equipment bay cooling fans if the cargo fire/ depr switch is pressed?
They are shut off
Which are the two valves used for each cargo heat section?
Shutoff valve and heat control valve
What are the two sources for cargo heat?
Cabin air and bleed air
What temp in the cargo compartment will cause the heat shutoff valve to close?
90f
Can you get a cargo overheat light in flight?
No its inhibited
When is cargo overheat light inhibited on the ground?
If the cargo heat switches are not turned on and the cargo compartment reaches 90f or more.
What does the vent position on the bulk cargo heat selector do?
It deactivates the bulk cargo heat system
What is the range on the landing altitude selector?
-1000 to 14000
What fans run on the ground in regards to the equipment cooling system in auto mode?
Both supply and exhaust fans run.
With regard to the equipment cooling sytem, if you are in auto mode and in the air, which fan runs?
Normally the exhaust fan runs.
If the exhaust fan fails, the supply fan takes over.
In regard to equipment cooling system, if you are in the air and you are operating in standby mode, which fan runs?
The supply fan will be signaled to run and will turn off the exhaust fan. However, during ops, the supply fan fails, the exhaust fan will take over.
What happens to both the supply fan and exhaust fan in override mode?
They are both turned off
What happens to the valves in the equipment cooling system during override operation?
They go into closed circuit mode. Everything will close except the smoke override valve will open.
In regards to equipment cooling, what will the valve positions be if you press cargo fire depress switch in flight?
It will be in the same closed circuit mode as in auto in flight. Everything will be closed except the smoke override valve will open to slowly depressurize the cabin.
The normal fan logic applies. The exhaust fan runs as in auto mode.
