Fuel System Flashcards
Tanks
1 integral tank/ wing
Fuel distribution
Under normal conditions each tank supplies the equidistant engine through a collector tank located at the inboard of each tank.
APU
Is supplied by the engine’s 2 collector tank.
Is fed my electrical pumps when engines are not running or by the primary ejector pumps when the engines are running.
How are engines being fed
By primary injector pumps one each side which are driven by primary ejector pumps which are driven by high pressure motive fuel pumps.
AC pumps
They are to assure engine feed in the event of a primary ejector pump failure plus it provides a source of pressurized fuel supply to the engines and APU for ground and in-flight start.
Refueling and Defueling
Refueling and Defueling is made from the right wing but only Refueling can be done from the Gravity Refuel Adapter on the top of each wing.
It is designed to provide continuous pressurized fuel to the engines without pilot intervention.
Wing Tanks include
Surge tank to collect fuel during uncoordinated manœuvres or wing down
Collector tank to ensure continuous fuel feed.
Fuel distribution is made from outboards and into the collector tank.
Baffle and Flapper check valves on each wing to prevent fuel escaping from the collector tank and from entering the surge tank.
Tank vent system
Keeps differential pressure btwn the tank and ambient
Prevents fuel spillage
The vents are separated lines for each wing into the surge tank.
Drain valves
Due to gravity, water will be collected from collectors and wing tanks and drained through the drain valves
Fuel indication system
Electrical fuel quantity
Mechanical fuel quantity
Fuel temperature
Fuel low level indication (independent probe from the fuel quantity indication probe)
Type of determining fuel quantity
AC capacitance type electrical fuel indicating subsystem. In case this fails the back up system is operated by means of magnetic level indicators and allows the aircraft to be dispatched
Temp indication
Green when temp is -37< celsius
Amber when temp -37> celsius
Amber dashes when there is a fault
Fuel status indications
White when on Standby
Green when in operation
Amber dashes when there is a fault
Fuel warnings
When fuel drops <300kg a low level warning will be displayed on EICAS.
Important Notes
- in case of loss of the transfer system followed by the EICAS warning message, fuel quantity indication monitoring during the flight is achieved through the EICAS or the MFD fuels System synoptic page.
*Engine flameout is possible due to starvation if the airplane is submitted to attitudes 15degrees up/down, uncoordinated manœuvres or negative Gs
Engine feed system
Ensures continuous pressurized fuel during the aircraft operation by using ejector and electrical pumps
Fuel feed
Provides continuous supply of pressurized fuel to the engine during aircraft operation by using ejector and electrical pumps. It has also cross-feed valve that supplies fuel to both engines from either one of the wing tanks.
Has :
1 feed ejector pump / wing which is operated from motive flow supplied by the engine driven fuel pump
1 AC pump for each wing
When in primary pump failure the AC pump provides back up boost flow to the engine.
AC Bus 1……powers the AC Left pump
AC ESS Bus ……powers the AC Right pump
In case of electrical emergency the right AC pump fails it will be supplied by the Ram Air Turbine.
APU feed
Ensures a continuous supply of pressurized fuel to the APU
DC pump
Provides pressurized fuel for APU and engine start in flight or on the ground if the engine ejector pump or AC power or AC pump are not available. Electrical power will be supplied by the DC ESS Bus 2
Knob positions
If the AC pump knob is in the AUTO position then in case of the ejector failure the AC pump will start automatically.
If the knob is in the ON position the AC pump will be powered continuously.
Pressure switches
The pressure switches are connected to their dedicated fuel pump by a sensing line and send their signals to the MAU’s.
MAU 1 monitors the status of the AC fuel pump 1
MAU 3 monitors the status of the AC fuel pump 2 and the DC fuel pump pressure switches.
The MAUs transmits the data on the ascb for EICAS display and control functions.
