Operate Fuel Systems Flashcards
What is the purpose of a scavenge ejector?
Each wing fuel tank contains three (3) scavenge ejector jet pumps in each main tank that maintain the fuel level in the collector tank, ensuring a constant flow of fuel to the engine during normal flight.
What is the primary purpose of the Main Ejector?
The main ejector is the primary pump that is used to transport fuel from the collector tank to the engine.
It has no moving parts. It relies on motive flow from the engine driven fuel pump (EDP).
Pilots do not have direct control over the ejector pump or the engine driven fuel pump. Both should operate when the engine is running.
With the knob in AUTO, when will the AC Fuel Pump 1 and 2 turn on?
AC Fuel Pump 2: Draws from the right tank only
AUTO- turns the pump ON when:
-Engine 2 is starting, or
APU is starting or running without engine 2 running, or
XFEED selected to LOW 1, or
Main Ejector pump 2 fails
AC Fuel Pump 1: Draws from the left tank only
Auto- turns the pump ON when:
Engine 1 is starting or
XFEED selected to low 2, or
Main ejector pump fails
With the knob in AUTO, when will the DC Fuel Pump turn on?
Automatically commands the pump ON when:
-ENG 2 or APU is started and AC Fuel Pump 2 is not available
What does the XFEED knob do?
For 800 lbs or more of fuel imbalance, a fuel imbalance caution message will display on EICAS. Follow the QRH to resolve this.
To balance fuel when the imbalance is 704 lbs or less, select the low fuel tank.
Low 1: Opens the crossfeed valve and automatically activates the right AC fuel pump (AC PUMP 2), supplying fuel to both engines from the right wing tank
Off: Selector must be in OFF for takeoffs and landings
Low 2: Opposite of Low 1
Which fuel pumps are in the main fuel tanks? How many are there?
Each wing has 3 scavenge ejector pumps.
Which fuel pumps are in the collector tank in each wing? How many are there (pumps and collector tanks)?
The fuel system contains two integral fuel tanks with one tank located in each wing. Each wing tank incorportes:
-a collector tank
-a surge tank
Each wing fuel tank contains the following pumps:
-Ejector fuel pump
-Wing AC electric fuel pump
-Three scavenge ejector pumps
-DC electric fuel pump (right tank only)
Scavenge pumps
-Three scavenge jet pumps maintain the fuel level in the collector tank, ensuring a constant flow of fuel to the engine during normal flight
Recite Fuel Limitations: Max Imbalance
794 lbs
Takeoffs and landings are not permitted with an imbalance of more than 794 lbs.
Recite Fuel Limitations: Max QTY
20,935 lb
Recite Fuel Limitations: Min Temp
-37 degrees C
When will a FUEL IMBALANCE EICAS message appear? When will it go away?
Fuel imbalance: Indicates an imbalance of fuel between the two tanks greater than or equal to 800 lb. It remains displayed until the imbalance is reduced to 100lb.
In the event of a dual engine failure, which fuel pump will provide fuel to relight an engine?
*Check
DC fuel pump
AC fuel pump 2A
