Fuel System Flashcards
Overview 1
Two separate integral wing fuel tanks provide fuel for the engines and APU.
Fuel is automatically fed to the engines and APU during starts and while running. The flight crew has partial control of the boost pumps and full control of cross feed operations.
Overview 2
Fuel in the tank is transferred to a hopper tank in the lower section of each wing. From there it is delivered to the engines and APU through a system of pumps and fuel lines.
Normally each tank supplies it’s respective engine with fuel. The APU gets its fuel from the right tank. Crossfeeding is capable to either engine and the APU.
How many probes are found per wing?
The system consists of seven compensated capacitance probes per wing.
What type of signal conditioner is found in the fuel system?
A dual-channel fuel quantity signal conditioner.
Where are the boost pumps found?
One electrical fuel boost pump in the hopper of each tank supplies fuel to the respective engine-driven fuel pump.
Describe the crossfeed valve.
The crossfeed valve is a main DC-powered, motor driven ball valve controlled by the crossfeed selector in the cockpit.
Where is the cross feed valve found?
In the fuel tank area and connects to the left and right engine supply lines.
What happens when an individual tank quantity display is less than 500 pounds?
The respective digital text changes from green to amber inverse video.
What happens if the total quantity is less than 1000 pounds?
The digital text changes from green to amber inverse video.
The condition does not activate a CAS message.
Boxed fuel flow digits are above the fuel quantity displays to indicate engine fuel flows based on input from a fuel flow transducer on each associated engine.
A
How is the fuel temperature measured?
With fuel temperature sensors in each fuel tank.
How is the fuel temperature displayed?
The temperature is always displayed as white digits at the bottom of the fuel area on the EICAS.
FUEL BOOST in the ON position.
The ON position indicates either manual selection or automatic activation due to low fuel pressure.
FUEL BOOST button in the NORM position.
In the NORM position the fuel boost pump automatically activated for the following reasons:
- Engine start.
- Crossfeed.
- APU operation, if right engine is not running.
- Low fuel pressure.
