Skyblue CBT fuel system Flashcards
what can each wing tank carry?
2500kg of fuel
how much does the feeder tank carry?
160kg
what is the feeder tank used for?
ensures that fuel is available for pumping through all flight manouvres
what does the feeder tank use to pump fuel?
an electric pump and a jet pump
what is max fuel imbalance between tanks?
730kg
what are the 2 fuel lines that cross the wing center box used for?
1 for crossfeed and the other for refueling the left tank
what does the vent line do?
prevents concentration of fuel vapour
what does the ven system do?
keeps a positive pressure on the fuel in the tanks while the aircraft is pitching and rolling
where are the surge tanks?
outboard section of the wings. fuel is vented to these tanks
what does the NACA vent?
provides atmospheric pressure to the surge tank and prevents ice accumulation on the surge tank inlet
what does the float valve do?
allows fuel to collect into the surge tank before it is returned to the fuel tank via the vent duct
how is excess fuel drained in the event of overfuel?
through the surge tank inlet into the surge tank
how long does it take to completely refuel the aircraft?
16 mins
what is max pressure for fueling?
50 psi
what can we not do when refueling?
- operate switches
- smoke
- use a phone
- refuel near a thunderstorm
what controls flow of fuel during refueling to each wing tank?
2 solenoid refuel control valves downstream of the refuel connector
what happens when the refuel valves are opened?
fuel flows to the associated tank and dispensed through diffusers
what normally closes the refueling valves?
fuel quantity indicating system in the FCU closes the valves when the tank reaches 2500kg
what is the purpose of the backup high level sensor in each tank?
control the refuel valve in the event of a malfunction of the Fuel indicating systems high level sensor
how is defueling carried out?
by applying 11 psi suction to the connector and opening the refueling valves
how many litres will the feeder tank hold?
200L
what is the purpose of the electrical pump?
supplies fuel to one engine throughout the whole flight envelope
what powers the electric fuel pump?
DC ESS BUS
What can the electric fuel pump and its associated jet pump do?
can supply both engines throughout the entire flight envelope
when can one jet pump not supply both engines?
when using jet b fuel
when is the electric fuel pump mainly used?
for engine start. it shuts down once the engine is operating
what 2 directions does the elctrical fuel pump send fuel?
- through a check valve and out to the LP fuel valve
- through a check valve to a feeder jet pump in order to refuel the feeder tank
when is the LP fuel valve closed?
when the fire handle is pulled
what is required to close the LP valve?
electrical power from the HOT EMER BAT BUS or the associated DC BUS
where does fuel flow after the LP valve? (in order)
- fuel heater
- HP pump
- fuel filter
- hydro mechanical unit (HMU)
- engine
where does the HMU send fuel?
- engine
- to the motive flow valve to provide pressurised fuel to operate the jet pump
what controls the motive flow valve?
button on LH overhead panel
how is fuel pumped back to the feeder tank?
tapped off the engine jet pump and fed through a check valve to the feeder jet pump
what does the pressure sensor monitor?
output of each feeder jet pump
what if fuel pressure drops below 5psi?
electric jet pump starts automatically as long as the button is pushed in
what does FEED LO PR mean?
fuel pressure below 4 psi
what will both electrical pumps do during crossfeed operations?
automatically start as long as the buttons are pushed in
at what feeder tank level will the electric fuel pump begin to operate?
below 160kg. this is accompanied by FUEL LO LVL on EWD
what powers the fuel crossfeed valve?
DC ESS BUS
how many fuel probes are there per tank?
6
what does the fuel quantity system operate based on?
dielectric constant of fuel and fuel density
what is used to measure fuel quantity on the ground in the event of an indiczting system failure?
magnetic fuel indicator which measures amount in cm
what do the pump push buttons control?
electric fuel pump and motive fuel valve
when will the motive fuel valve close?
when sufficient fuel pressure is unavailable
when will the electric fuel pump automatically switch off?
when jet pump pressure exceeds 8.5psi for 30 seconds
what does 2 amber dashes on the fuel temp readout mean?
invalid data
what does an amber LP valve indication mean?
LP not open or closed after 3 seconds
what does a CLOG caution mean?
excessive pressure loss at the fuel filter
how many magnetic level indicators are there in each tank?
2
