PNEUMATICS Flashcards
What systems requires bleed air?
Air Conditioning
Wing Anti-ice
Engine Starting
Hyd reservoir pressurization
Water pressurization
Where can the bleed pressure be supplied from?
Engine bleed
APU bleed
External HP ground connection
What engine stage normally provide bleed air?
The IP stage
Can bleed air be supplied simultaneously from the IP and the HP sources?
No
When would HP bleed air be used?
During times when IP bleed pressure is not enough such as idle descents or ground operations
How is the bleed air cooled?
With a pre-cooler using cool air from the engine fan section
What is the max altitude for APU bleed?
20’000 ft
What side of the pneumatic system is the APU connected to?
The nr 1 engine side
What source bleed air source has the highest priority?
The APU
What is a limitation to be observed with HP external bleed air connected?
Do not use any other bleed air source
What is a BMC in the pneumatic system?
Bleed Monitoring Computer
How many BMC:s are there in the pneumatic system and what are their functions?
There are two. One for each bleed system.
They receive temp, press and valve position and controls the bleed valves
What is special about BMC 1 in the pneumatic system?
It also controlls the APU
What happens if one BMC fails in the pneumatic system?
The other takes over as they are interconnected
Where are the bleed leak detection loops located?
APU ducting
Engine Pylon ducting
Wing ducting
What is the indication that HP GND air is being used?
No indication other than pressure and temp indications on ECAM
Does the BMC:s control the HP GND air?
BMC:s have no control over the GND HP air connection
What does the bleed leak detection loops detect?
High temperature changes
How are the crew alerted that a bleed leak is detected?
Which system sends the message?
A message is sent to the BMC:s and pilots are alerted via ECAM
Where is dual bleed leak loop detection installed?
In the wings, and the portion forward of the APU bleed valve
When would the Engine Number on the BLEED page be amber?
When the engine is shut down or below idle
In what two ways can a pilot close the engine bleed valve?
- ENG BLEED pb set to OFF
- ENG FIRE pg pressed
For what situations would the BMC:s 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
How is the X BLEED VALVE controlled?
Normally automatically but it can also be manually controlled
What is the indication of the X BLEED VALVE if it’s not in it’s commanded position?
Valve will be amber
How can you manually isolate the left side of the pneumatic system from the right?
By using the X BLEED switch and set it to SHUT
How would you know that the APU is switched off by looking at the bleed display only?
Only the letters APU are visible. The valve indication would be gone
What is the indication on the bleed page if the APU pb is switched on?
The bleed valve appears above the APU letters
When will the X BLEED valve automatically open?
When the 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 open 30 seconds after start sequence
During an engine bleed failure, can you use APU to supplement air pressure?
No, if APU bleed is selected this will automatically close both engine bleed valve
What is an icing equipment limitation during a bleed leak?
You can’t cross feed bleed air as this would feed it to the leak
During a bleed leak can you keep wing anti-ice ON?
No because you are not allowed to cross feed during a leak. You will be directed turn off wing-anti ice as you don’t want asymmetrical de-icing
On the SD, when is GND displayed on the bleed page?
Only on the ground
What is the normal bleed air pressure from the IP stage?
42 psi +/- 3 psi
May fluctuate +- 8psi
What is the temperature regulated to by the pre-cooler in the bleed system?
Approximately 200 deg C
With the X BLEED selector in AUTO, what would cause it to close or open?
Closes when a leak is detected
Opens when the system uses APU bleed air
How is the X BLEED valve controlled technically?
By 2 electric motors, one for automatic and one for manual mode
What happens if a bleed leak occurs with the X BLEED selector in AUTO?
It closes, except during engine start
Does the overhead panel BLEED FAULT light extinguish when the temperature drops following a bleed overheat condition?
No, the light goes out only if the ENG BLEED pb sw is selected to OFF if the fault has disappeared
Is WAI allowed if only one bleed system is operating?
Yes
Which failures in the bleed system causes an ECAM warning?
Overpressure and overtemperature
How is the APU bleed valve operated and controlled?
Controlled electrically
Operated pneumatically
What part of the bleed leak detection system uses single a single loop system?
APU and the pylons
For the APU it’s dual loop forward of the shut-off valve
What does an Amber FAULT light in the APU BLEED pb indicate?
Bleed leak (APU bleed valve closes)
If the APU is running, is it necessary to manually select APU BLEED OFF prior to APU shutdown?
No
When the APU MASTER sw is selected OFF, the bleed air valve is closed and the APU is allowed to cool prior to shutdown
If one BMC fails, can the other one take over? What functinality is lost?
Yes, the other can take over and it produces the warning
Associated overtemperature protection is lost, and the associated bleed valve does not close automatically. You have to manually close it
ECAM AIR APU BLEED LEAK alert is lost if BMC 1 fails.
What happens if engine bleed air, in-flight, is too low, what will occur?
Air will be taken from the HP stage and if that’s not enough the engine speed will increase
After engine start with the APU BLEED pb ON, what source is supplying bleed air to the packs?
The APU bleed
At what psi value will the HP valve in the pneumatic system start operating?
When the psi output from the IP stage goes down to 65 psi.
Why is bleed air taken from the IP stage and not the HP stage?
To minimize fuel penalty
When will the pre-cooler inlet pressure indication turn amber?
When psi is below 4 psi or over 57-60 psi
When will the pre-cooler outlet temperature turn amber?
Over 290 deg C for more than 5 sec
Over 270 deg C for more than 15 sec
Over 257 deg C for more than 55 sec
What is the purpose of the overpressure valve in the pneumatic system and when will it close?
Acts as a last resort if the engine bleed valve can’t regulate the pressure. Closes at 75 PSI
Which bleed source has the highest priority?
Bleed from the APU
When is the GND air symbol displayed?
On the ground
