Pneumatics Flashcards
What systems require bleed air?
Air Conditioning
Wing Anti-Icing
Engine Starting
Hyd reservoir pressurization
Water pressurization
Where is the pressure supplied from?
Engine bleed
APU bleed or
External High Pressure ground connection
Bleed air is usually supplied from the Intermediate Pressure stage except for…
Idle conditions where the High Pressure stage supplies the bleed air.
Note: IP and HP bleed is never used at the same time
How is the bleed air cooled?
With a pre-cooler using cool air from the fan section
What is the max altitude for APU bleed?
20,000 feet
What side is the APU bleed connected to?
1 engine side, the crossfeed valve supplies APU bleed to both sides
What is unique about APU bleed air priority?
The APU has priority supplying bleed air
What is a limitation with the External High Pressure air connection?
When connected, DO NOT use any other bleed source!
Where are the leak detection loops?
APU ducting
Engine Pylon ducting
Wing ducting
What does BMC1 control?
Bleed air from Engine 1 and APU
What is special about the wing ducting?
There are 2 leak detection loops in the wings. Each monitored by different BMCs. Both loops must detect a leak for a pilot alert. Otherwise, the leak is automatically isolated.
Why would the Engine Number on the BLEED page be amber?
When the engine is below idele (off)
What happens to the associated PACK when you manually close an engine bleed valve?
Turning off the engine bleed valve automatically shuts off the associated Air Conditioning PACK.
How is the engine bleed valve closed by the pilot?
END BLEED pb OFF
OR
ENG FIRE pb engaged
Why would the BMC close the engine bleed valve?
Over temp
Over Pressure
Bleed Leak
Engine Start sequence
APU Bleed selected ON
How would Physics close the engine bleed valve?
No air pressure (spring loaded closed)
If reverse pressure is sensed
When will the auto X BLEED valve open?
When APU bleed is selected on.
What happens to the PACK control valve during engine start?
They automatically close to provide max pressure for engine start.
They will auto open ~30 seconds after start sequence
If a engine bleed fails during icing conditions, what is a limitation?
One engine bleed CAN NOT operate both PACKs when de-icing is on
During an engine bleed failure, can you use APU to supplement pressure?
NO, remember if you select APU bleed this will automatically close both engine bleed valves!
What is a icing limitation during a bleed air leak?
You CANNOT XFEED bleed air because of the leak as this will feed it the leak. Since you do not want to de-ice only one wing, you must depart icing conditions.
