Bleed Air Sytem Flashcards
The bleed air system is divided into how many ducts?
Two ducts ( Left pneumatic duct & Right pneumatic duct)
How are the ducts connected?
The two ducts can be connected through an isolation valve
Which duct does the APU introduce bleed air into?
The left pneumatic duct
Which duct does pressurized air from a ground source supply bleed air into?
The right pneumatic duct
What is bleed air used for?
Engine starting
Engine anti-ice
Wing anti-ice
Air conditioning & pressurization
Water tank pressurization
Hydraulic reservoir pressurization
Used by NGS (Nitrogen Generation System)
What is installed to monitor bleed air pressure and temperature?
Bleed trip sensors
How is the pressure controlled?
Pressure is controlled by the engine bleed air valves which act as Pressure Regulator and Shutoff valves (PRSOV)
During flight the engines normally supply bleed air for the pneumatic system. What stages within the engine compressor section is the air supplied from?
The 5th stage or low pressure stage ( Primary Source )
The 9th stage or high pressure stage ( Back-up Source )
What happens when 5th stage air is insufficient for bleed air system requirements?
The 9th stage valve modulates open to maintain adequate pressure.
How are the engine bleed air valves Controlled?
They are electrically (DC Power) by the engine bleed air switch.
When do the bleed air valves open?
The valve is pneumatically operated and opens once sufficient pressure is available. After the engine is started, bleed air pressure from the engine opens the bleed air valve.
What happens when the bleed air temperature is high as it passes through the bleed air valve?
The engine bleed air valve reduces bleed air outflow.
What happens when the engine bleed air temperature or pressure exceeds a predetermined limit?
The BLEED TRIP OFF light illuminates. This causes the valve to automatically close.
What are the three isolation valve switch positions?
Close
Auto
Open
What causes the isolation valve to open?
- Isolation valve switch in the open position
- Isolation valve switch in the Auto position and placing any one of the PACK switches or ENGINE BLEED AIR switches to the off position.