Fuel System Flashcards
How many fuel tanks on freighter?
7 total
Center Tank Capacity?
52.1 kg
Main Tanks 2 & 3 Capacity?
38.1 kg
Main Tanks 1 & 4 Capacity?
13.2
Reserve Tank Capacity?
4 kg each
Total Fuel Capacity?
163,042 kg
What commands fuel valves and pumps to function?
FSMCs
Fuel System Management Cards
Which crossfeed valves are affected by flap extension on the ground?
2 & 3
- They are closed by the FSMCs when flaps extend to takeoff position on the ground
Which fuel pumps are commanded to turn ON and OFF by system logic during normal OPS?
Overide/Jettison Pumps 2 & 3
- They are inhibited from operating when pressure is detected from both CWT pumps.
With more than 7700 kgs in CWT, trace flow of fuel (for takeoff)?
- Both CWT pump switches should be ON
- XFEED valves 2 & 3 CLOSE w/flaps set for takeoff
- CWT pumps feed ENG 1 & 4
- Main pumps 2 & 3 feed related engine
With less than 7700 kgs in CWT, trace flow of fuel (for takeoff)?
- Both CWT pump switches should be OFF
- XFEED valves 2 & 3 CLOSE w/flaps set for takeoff
- O/J Pumps 2 feed ENG 1
- O/J Pumps 3 feed ENG 4
- Main Pumps 2 & 3 feed related engine
When do FSMCs open the reserve transfer valves?
- When main tank 2 or 3 quantity decreases to approx 18,200 kgs.
- Valves OPEN and fuel gravity transfers to main tanks 2 & 3.
When would fuel automatically transfer from main tanks 1 & 4 to their adjacent tanks 2 & 3?
During fuel jettison, when either main tank 2 or 3 fuel quantity decreases to 9,072 kgs.
Can fuel be manually transferred from tank to tank?
- Only with the Main Tank 1 & 4 Transfer Switch on the overhead panel.
- Fuel transfers from outboard to inboard main tanks, until approx 3,200 kgs remain in each outboard tank.
What occurs when we select the Fuel Jettison Switch to A or B?
- Arms the jettison selector
- Display preselected fuel to remain on EICAS
How does fuel quantity indication change upon termination of fuel jettison?
- The fuel to remain quantity indication changes to white & flashes for 5 seconds
What occurs when you push either fuel jettison nozzle valve to ON during the QRH fuel jettison procedure?
- Activates all O/J pumps in the tanks containing fuel
- Related jettison nozzle valve OPENS
Generally speaking, how do we handle a fuel imbalance?
With use of XFEED valves and fuel pump switches
* Refer to QRH
How does excessive fuel imbalance impact aircraft?
- Adversely affects CG
- Aerodynamic drag
- Fuel Economy
When is an engine suction fed and how would you correct a suction feed situation?
- An ENG is on suction feed w/main tank pressure is LOW
- Open appropriate fuel XFEED valve from a main tank with operating pumps.
Does the suction feed line go through the main tank fuel pumps?
NO, the suction feed line bypasses the pumps
A single main tank fuel pump can provide sufficient fuel to how many engines?
- One ENG at takeoff thrust
- Two ENG at cruise thrust
A single main tank 2 or 3 O/J pump can provide sufficient fuel to how many engines?
Two ENG at takeoff and cruise thrust
Can the main tank 2 or 3 O/J pumps operate when the related main tank is below 3,200 kgs?
NO
Where is fuel tank temp measured?
Main Tank 1
When does the fuel temp display on primary EICAS display in amber?
-37C or less
How is CWT fuel scavenged?
- By 4 jet pumps, two pumping into each main tank 2 & 3
- Begins w/ main tank 2 or 3 fuel qty decreases to approx 27,200 kgs
Fuel imbalance generated EICAS messages come on?
1360 between tanks 1 & 4
2720 between tanks 2 & 3
2720 between inboard & outboard tanks after FUEL TANK/ENG
When does IMBAL message on EICAS go away?
When difference is less than 450 kgs
What does a Crossfeed Valve ON, bar visible, indication mean for Crossfeed Valve Switches 2 & 3?
XFEED valve will OPEN per system logic
What does a Crossfeed Valve ON, bar visible, indication mean for Crossfeed Valve Switches 1 & 4?
XFEED valve is OPEN
What does is mean when main tank 2 & 3 OVRD Fuel Pump Switches are ON?
Fuel pump operates when commanded by system logic.
What is the correct way to reconfigure for FUEL TANK/ENG?
O/J Pumps Switches 2 & 3 - OFF
Crossfeed Valve Switches 1 & 4 - OFF
Why should we wait until we get a fuel imbalance message before balancing fuel?
Because the first step in a fuel imbalance checklist is to determine if a fuel leak exists.
