11.16 Pneumatic and Vacuum Flashcards
What does the pneumatic system do?
Transfers energy through manipulation of air pressure.
What are the power sources for pneumatic systems?
Engines
APU
GPU
What four basic category systems are there?
Vacuum
Low pressure
Medium Pressure
High pressure
What is the main purpose of the vacuum system?
Gyros
How is the vacuum reduced for the turn and bank indicators?
Needle valves.
What is the low pressure system used for?
Anti-icing
What pressure does the medium system run at?
50-150 psi
When is engine LP or IP air used?
During take off, climb and cruise.
When is APU bleed air available?
When it is running above 95%
What three types of compressor are there?
Positive displacement
Multi stage
Centrifugal
What do stack pipes do?
prevent contamination from passing to the system or pressure gauge.
What does a rotary compressor look like?
Two screwjacks
What two types of vacuum pump are there?
Wet
Dry
How is the wet pump design been improved?
Incorporating carbon into the vanes and rotor.
How are venturi tubes rated?
When they produce 120mph
What are the two inch venturis used for?
Two inches of Mercury suction to drive one turn and bank indicators
What are 4 inch venturis used for?
Directional and attitude gyros
What is the purpose of a check valve?
One way
Where is the moisture separator located?
Downstream of the compressor
What system automatically controls the pneumatics?
Air supply control and test unit (ASCTU)
What is the duct pressure?
20 psi
What is the flow of air in a duct approx?
10 lbs/sec
With the fan air valve, the higher the temp rises what happens?
The wider the valve opens
When does the engine bleed valve automatically close?
When the temp exceeds 254 degrees c
What does white circle with flow bar in-line with the duct mean?
Open
What does white circle with flow bar perpendicular to the duct mean?
Closed
What does amber valve open symbol with amber ‘X’ mean?
Failed open
The APU starter disengages at what RPM?
55%
