11.16 Pneumatic Systems Flashcards
What are the 3 sources a pneumatic system gets its power from?
engines, APU & GPU
What are the 3 main parts of a pneumatic duct system?
left wing ducts, right wing ducts & crossover ducts
What psi does a low pressure system produce, where does it get it from & what is it used for?
1-10psi, from engine or APU, used for anti-icing
What psi does a medium pressure system produce, where does it get it from & what is it used for?
50-150psi, from compressor section of turbine engine & used to pressurize reservoirs in a hydraulic system
What psi does a high pressure system produce, where does it get it from & what is it used for?
1000-3000psi, from metal bottles, used in pneumatic braking system
When is LP & IP bleed air used?
during take-off, climb & cruise
What 3 places is air bled of an engine compressor from & what type?
LP bleed port (twin shaft), IP bleed port (triple shaft) & HP bleed port
When is HP bleed air used?
when LP & IP bleed air is inadequate
When is APU bleed air available?
APU running above 95%
What are the 2 types of positive displacement, vane type vacuum pumps?
wet pumps & dry pumps
What are positive displacement, vane type vacuum pumps driven by?
engine accessory drive
How are wet pumps lubricated?
from engines LP oil system
What is the function of a separator in a wet pump?
Captures oil to prevent oil streaks across the fuselage
How are dry pumps lubricated?
self-lubricated
What are the vanes & rotor made of in a dry pump design?
carbon
What are the vanes made of in a wet pump design?
steel
What do Pressure Relief Valves (PRV) function as in a pneumatic system?
pressure limiting units
What keeps a PRV in the closed position?
spring
What is the duct pressure controlled to?
20psi
How is the Fan Air Valve (FAV) operated and what type of valve is it?
pneumatically operated - butterfly valve
What is the purpose of flow sensors?
monitor air supply in the distribution system
What is used to control the pneumatic system manually & then automatically
Pneumatic control panel - pneumatic controller
What is the main parameter controlled in the flight deck?
pneumatic manifold pressure
Where is the isolation valve control switch located?
overhead panel in the flight deck
Where are the overtemperature & duct sensors located, what are they controlled by?
ducting system - pneumatic controller
What is used to turn the core engine spool during engine starting?
pneumatic power
What is the function of the overpressure valve & when does it open?
protects users against overpressure - opens in case of PRV malfunction
