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Systems Ch.2 Pneumatics
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What systems are operated by pneumatic air
Air conditioning, Pressureizations, and ice protection
____ bleed air automatically supplements the ____ flow as necessary
during periods of low engine rpm
HP, LP
What compressor stage is the LP (P2.5) bleed air taken from?
5th
What compressor stage is the HP (P3) bleed air taken from?
6th
How is the HP valve controlled?
Electrically
How is the HP valve operated?
Pneumatically
If electric power to the HP bleed valve fails what position would the valve be in?
Closed
What are the reasons the HP valve would automatically close?
M ain DC power lost
O ver temp (bleeds) 288C
O ver pressure (bleeds) 76 PSI
F ire Handle Pulled
S hutdown Engine
If electric power to the LP bleed vlave fails what position would the vlave be in?
Open
What are the reasons the LP bleed valve close automatically
S witch Closed
A CM Temp over 225C
D uct (A/C) over 82C
F ire Handle Pulled
O ver temp (bleed air) 288C
O ver pressure (bleed air) 43 PSI downstream of valve
What does a BLD CLOSED light indicate
The respective BLD valve is closed
What does the BLD FAULT light indicate
The respective BLD valve recieved a close signal but did not close
Bleed Air Line Over Heat above 288C
Bleed Air Line Over Pressure above 43 PSI downstream of valve
What does a HP HIGH light indicate
The respective HP valve is stuck. Triggers AIR COND on CWP
How is HP bleed air cooled
Through a ram air heat exchanger (precooler)
A separate flow through the recooler acoomplishes _____ cooling for use by the pneumatic deicer system
LP bleed air
How are the pneumatic systems interconnected so that one bleed air source can supply both air conditioning systems
Cross Valve (X VALVE)
When can the cross valve be used
On ground only
What is required for he X Valve to open
One bleed valve must be open
How is the X valve operated
Pneumatically
How is the X VALVE controlled
electronically
What does a X VALVE OPEN light indicate
X Valve is open
What does a BLD AIR LEAK light indicate
Excessive temperature in bleed detection loop (engine to pack) above 205C. Triggers AIR COND on the CWP
Will a BLD LEAK close the LP bleed valve
No
What does a RECIRC light indicate
Failure of the recirc fan (less than 80%)
Will you get a Master Caution light for a Recirc Fan failing
No
What overhead light will not illuminated an AIR COND light on the CWP
L/R RECIRC light
When is the Auto mode of the temp control to be used
Always unless inop
Does the Manual mode of temp control provide temperature limiting protection to the system
No
In the Manual mode of temp control, how long does it take to move the control valve from one extreme to the other extreme
6-8 seconds
What does an AVIONICS VENT light on CWP indicate
Failure of the avionics vent fan
While in flight, if the PRESS DUMP switch is activated what happnes
The primary outflow valve is immediately fully opened
While on the ground if the PRESS DUMP siwtch is activated what happens
Both the primary and secondary valves are fully opened
In Auto Pressurization mode what is the max differential pressure
7.1 PSI
How long after touchdown is the promary outflow valve fully opened
20 seconds
Where is the primary outflow valve located
False bulkhead in the tail compartment
How are the outflow valves controlled
Elevtric and pneumatic
The outflow valves limit positive pressure to
7.6 PSI
The outflow valves limit negative pressure to
-0.5 PSI
If vacuum pressure is lost what position do the outflow valves revert to
Closed
In manual pressurization mode what position is the primary outflow valve in
Closed
What does the CABIN PRESS light indicate
Cabin altitude above 10,000' or cabin press exceeds 7.5 PSI
Where is the secondary outflow valve located on the Saab 340
Rear pressure bulkhead
The scondary outflow valve is normally only operated in what mode
Manual
What rate of cabin VSI does the detent on the auto controller provide
500 fpm up and 300 fpm down
When would the fault light on the pressurization controller illuminate
With a system failure
During a system self-test and extinguishes with no faults detected
Author
vicoliveira
ID
162337
Card Set
Systems Ch.2 Pneumatics
Description
Air Systems
Updated
2012-07-14T19:05:17Z
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