Terms in this set (37)
Can the pneumatic duct be pressurized by more than one system?
No, system logic prevents this, however the system is unable to detect external high pressure air connected for engine starting.
In case of a failure of one Bleed Management Computer (BMC), what happens?
The other BMC takes over the main function to ensure operation of both bleed systems, but bleed leak detection on the respective engine is no longer available and if BMC 1 fails, APU bleed leak detection is no longer available since the engines and APU have only 1 loop.
If IP air pressure or temperature is not adequate, what happens?
Air is bled from the HP stage compressor. A check valve prevents backflow into the IP stage. IP and HP stage air are never employed together.
When will the engine bleed valve automatically close?
1. Starting Engines
2. Lack of airflow (spring loaded closed)
3. APU bleed valve open
4. Reverse airflow
5. Fault (overpress, overtemp, bleed leak)
How can the pilot close the engine bleed valve?
Push the ENG BLEED or ENG FIRE pb
Open the APU BLEED
When APU bleed air is available and selected on, what happens to the engine bleed valves?
The APU bleed air has priority over the engine bleeds so the engine bleed valves automatically close.
Is wing anti-ice available using APU bleed air?
It is possible for APU bleed air to enter the wing A/I ducts, but since the APU bleed air has no heat exchanger, damage may occur because the air is too hot.
How is the crossbleed valve operated?
The valve has two motors, 1 for automatic mode and 1 for manual mode. In the event of an electrical failure, the valve will fail in the last commanded position.
What commands the crossbleed valve to open and close in automatic mode?
It is commanded open and closed by the BMCs. It opens when APU bleed air is used and is closed when APU bleed air is not used or a leak is detected.
What commands the crossbleed valve to open and close in manual mode?
In manual mode, control of the crossbleed valve is removed from the BMCs and is either OPEN or SHUT according to the knob on the overhead panel.
When a bleed leak is detected, what happens automatically?
The BMC(s) command the appropriate valves to close to isolate the bad duct.
Where is bleed leak detection provided?
Engine and pylon (1 loop connected to respective BMC)
APU (1 loop connected to BMC 1)
Wings (2 loops connected each connected to a BMC)
Do we ever take off with the engine bleeds off?
No, we take off with PACKs OFF or APU bleed ON, but never with engine bleeds OFF
What happens if both BMCs fail?
The pilot can still control the engine and APU bleed valves and the crossbleed valve. Bleed leak protection is not provided.
What does a FAULT light on the ENG BLEED pb indicate?
1. Overtemp or overpressure
2. Disagreement between commanded and actual valve position
3. Bleed leak is detected
What does a FAULT light on the APU bleed pb indicate?
Bleed leak is detected
How do you operate both PACKs with one engine running and the APU off?
Open the XBLEED valve manually
The pneumatic system is designed to provided air pressure for what purposes?
1. Air conditioning
2. Engine starting
3. Wing anti-icing
4. Hydraulic reservoir pressurization
5. Potable water pressurization
High pressure air can be supplied to the pneumatic system from what three sources?
1. Engine 1 and 2 bleeds
2. APU bleed
3. High pressure ground connection
Engine bleed air is normally supplied to the pneumatic system from where?
From the intermediate pressure (IP) stage of the high pressure compressor
Why is there a check valve on the IP stage of the engine bleed?
To prevent HP air backflow into the IP stage
What are the two functions of the engine bleed valves?
1. Pressure regulation
2. Shut off valves
In what situation is it possible to have more than one bleed air source at a time?
When using external high pressure air. The BMCs do not recognize when external air is connected and therefore will not automatically reconfigure the engine or APU bleed valves.
With the XBLEED valve in AUTO, in what situation will the valve open?
When APU bleed air is in use
With the crossbleed valve in AUTO, in what situations will the valve close?
When APU bleed air is not in use or when a leak is detected in the pneumatic system.
The High Pressure Ground Air and the APU bleed air are supplied to which side of the pneumatic system?
How can you tell if High Pressure Ground Air is connected?
The green GND icon on the ECAM Bleed System page indicates both temperature and pressure.
What are the three zones the leak detection system is divided into?
1. Engine (including pylon)
2. Wing (including crossbleed duct)
3. APU (including APU duct)
Which pneumatic system ECAM valve indicator always displays green even during transit?
APU bleed valve
With the X BLEED selector in AUTO, the Engine Bleed Valves will be ______________ when the APU Bleed Valve is open.
With the X BLEED selector in AUTO, the XBLEED Valve will ____________ when the APU bleed valve is open and APU air is supplied to the pneumatic system.
With the X BLEED selector in AUTO and the engine bleed valves are selected ON with both engines running, the X BLEED valve will ___________ automatically.
If High Pressure Ground Air is applied to the Pneumatic System, will the X BLEED valve automatically open?
No. It will have to be manually opened.
If High Pressure Ground Air is to be used after parking, the X BLEED selector must be positioned to ____________ and the APU BLEED must be switched ____________.
If the engine bleed air inflight is too low, what will happen?
Engine speed is automatically increased to provide adequate bleed air pressure (modulating idle)
What is the purpose of the engine bleed air heat exchanger?
To provide cooling air from the fan stage of the engine to limit the engine bleed air temperature to approximately 200 C.
Does the APU bleed air have a heat exchanger?
No. There is no APU bleed air temperature regulation. Therefore, APU bleed air should never be used for wing anti-ice because the slats maybe damaged by excessive heat.
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