Engine bleed Flashcards
Which compressor stages correspond to the IP stage and HP stage in the CF6 engine?
Intermediate Pressure (IP) stage = HP stage 8
High Pressure (HP) stage = HP stage 14
What happens to the HP valve and IP check valve at low power settings?
The HP valve opens at low power settings. This closes the IP check valve, preventing backflow of air from the HP stage into the IP stage.
What pressure does the HP valve regulate air to?
The HP valve regulates air to 36 psi.
What pressure does the Pressure Regulating Valve (PRV) regulate air to?
The PRV regulates air to 50 psi.
What type of air is used to cool bleed air in the precooler?
Fan air is used to cool bleed air in the precooler.
How is the fan air flow regulated to cool the precooler?
The Fan Air Valve (FAV) modulates the flow of fan air across the precooler.
What are the two bleed air temperature settings after passing through the precooler?
200°C & 150°C
Each temperature setting has its own probe for monitoring.
What determines whether the 150°C or 200°C setting is used for bleed air cooling?
-The 150°C setting is commanded by the Zone Controller for air conditioning demand.
-The 200°C setting is used if Wing Anti-Ice is active.
Where is the Overpressure Valve (OPV) located in the pneumatic system?
The Overpressure Valve (OPV) is located between the PRV and the precooler to protect the system from excessive pressure.
What happens if there is an over-temperature coming out of the precooler?
A control thermostat solenoid can modulate the PRV to reduce bleed air temperature.
At what temperature does the BMC command the PRV to close?
At 257°C, the BMC (Bleed Monitoring Computer) commands the PRV to close to prevent overheating.
What happens if the bleed air temperature is too low?
1- A low temperature ECAM warning is triggered.
2- The bleed temperature is displayed in amber on the SD.
From where is hydraulic reservoir pressurization air tapped?
It is tapped from 14th stage bleed air on Engine 1 only.
Where is the Transfer Pressure Transducer located, and what does it monitor?
The Transfer Pressure Transducer is installed downstream of the HP valve and upstream of the PRV.
It provides information on the HP valve position.
What two cockpit actions will close the PRV?
The PRV will close if:
1- The Fire Handle is released.
2- The Bleed Pushbutton is pressed.
What controls the Fan Air Valve (FAV)?
The FAV Control Thermostat controls the Fan Air Valve by supplying and regulating motive pressure based on the precooler outlet temperature.
When does automatic isolation occur in the pneumatic system?
Auto isolation occurs in the following conditions:
1- Pylon or wing leak detected.
2- Overpressure condition.
3- Overtemperature condition.
4- During engine start.
5- When APU bleed is supplying air.
What components make up the bleed temperature regulation system?
The bleed temperature regulation system comprises the following components:
1- Fan Air Valve (FAV) associated with a control thermostat.
2- Precooler.
3- Bleed temperature sensor
What type of sensor is the outlet temperature bleed sensor, and where is it located?
The outlet temperature bleed sensor is a dual sensor, with each element feeding temperature data to one of the BMCs. It is installed in the bleed duct downstream of the precooler.
How is the Fan Air Valve (FAV) pneumatically controlled?
The FAV is pneumatically controlled by the FAV Control Thermostat, which supplies and regulates the FAV motive pressure based on the precooler outlet temperature. The pressure to the FAV is modulated by the expansion of the thermostat elements.
What happens to the Fan Air Valve (FAV) if no motive pressure is present?
The FAV is spring-loaded closed if no motive pressure is present.
How many position microswitches does the Fan Air Valve (FAV) have?
The FAV has two position microswitches.
