FUEL SYSTEM Flashcards
How many fuel tanks do we have and what are their approximate capacities?
• 7 fuel tanks • 1 and 4 mains = 13.2kgseach • 2 and 3 Mains = 38.1kgs each • center tank = 52.1 kgs. • 2 and 3 Reserves = 4.0.kgs. each • total capacity = 163, 042 FCOM, VOL 2; 12.20.4
When do the FSMCs open the reserve transfer valves?
• When either main tank 2 or 3 fuel quantity decreases to
approximately 18200 kgs.
• Fuel transfers from reserve tanks 2 and 3 to the related main
tank.
FCOM, VOL 2; 12.20.12
Under what conditions would fuel automatically transfer from main tanks 1 and 4 to their adjacent tanks 2 and 3?
• During fuel jettison, when either main tank 2 or 3 fuel quantity decreases
to 9072 kgs.
- Transfer will cease when outboard main tanks reach approximately 3200 kgs.
FCOM, VOL 2; 12.20.12
Can fuel be manually transferred from any tank to another tank?
• Yes, there is a FUEL XFER MAIN 1&4 switch on the
overhead panel.
• Fuel can transfer from the outboard to the inboard main
tanks, to approximately 3200 kgs remaining in each outboard
main tank.
FCOM, VOL 2; 12.20.12/12.20.6
State what occurs when you select the Fuel Jettison Switch to A or B?
• Arms the jettison system,
• Displays preselected fuel to remain, replacing fuel temperature on
primary EICAS display.
• Jettison manifold and jettison time display on the fuel synoptic.
FCOM, VOL 2; 12.10.3/ 12.20.16
Describe how the fuel quantity indication changes upon termination of fuel Jettison?
• The fuel to remain quantity indication changes from
magenta to white, and
• Flashes for 5 seconds.
FCOM, VOL 2; 12.20.17
What occurs when you push either fuel jettison nozzle valve to ON during the QRH fuel jettison procedure?
• It activates all override/jettison pumps in the tanks containing fuel,
(pump switches must be on).
• The related jettison nozzle valve opens.
FCOM, VOL 2; 12.20.16
What is the source of fuel for the APU?
• Normally supplied from main tank 2.
• When ac power is available, fuel is supplied by main pump 2 aft.
• If AC power is not available, a dedicated DC pump in main tank 2
supplies fuel to the APU.
• Main pump 3 aft operates to prevent tank to tank transfer and
provides fuel if main pump 2 aft fails. ( Backup for AFT pump 2)
FCOM, VOL 2; 12.20.10
In general, how would you handle a fuel imbalance situation?
• By opening or closing crossfeed valves and turning off and on fuel pump switches (refer to QRH and Supplementary Procedures)
FCOM, VOL 2; 12.20.3/SP 12.1
What is the impact on the aircraft of excessive fuel imbalance?
• Adversely affects CG
• Aerodynamic drag
• Fuel economy
FCOM, VOL 2; 12.20.3
When is an engine on suction feed, and how would you correct a suction feed situation?
• An engine is on suction feed when main tank fuel pressure is low.
• Open the appropriate fuel crossfeed valve from a main tank with
operating pumps. ( Caution, continued operation in this configuration
can cause a fuel imbalance.)
FCOM, VOL 2; 12.20.3
Does the suction feed line go through the main tank fuel pumps?
• No, the suction feed line bypasses the pumps
FCOM, VOL 2; 12.20.3
A single main tank fuel pump can provide sufficient fuel to how many engines?
• One engine at takeoff thrust
• Two engines at cruise thrust.
FCOM, VOL 2; 12.20.2
A single main tank 2 or 3 override/jettison pump can provide sufficient fuel to how many engines?
• Two engines at takeoff and cruise conditions.
FCOM, VOL 2; 12.20.2
Can the main tank 2 or 3 override/jettison pumps operate when the related Main tank is below 3,200 kgs?(standpipe level)
• No
FCOM, VOL 2; 12.20.2
Fuel tank temperature is measured in which tank?
• Main tank 1
FCOM, VOL 2; 12.20.1
When does the fuel temperature display on primary EICAS display in amber?
• -37C
FCOM, VOL 2; 12.20.1
How is Center Wing Tank Fuel scavenged?
• CWT fuel is scavenged by 4 jet pumps, two pumping into each
main tank 2 and 3.
• Scavenge begins when either main tank 2 or 3 fuel quantity decreases to
approximately 27200 kgs.
FCOM, VOL 2; 12.20.2
What are the fuel imbalance differences that would generate an EICAS Advisory message?
• 1360 between tanks 1 and 4
• 2720 between tanks 2 and 3
• 2720 between inboard and outboard tanks after FUEL TANK/ENG
FCOM, QRH 12.4/12.6/12.8
When correcting a fuel imbalance condition, when would you expect the associated EICAS Advisory IMBAL message to no longer display?
• When the difference is less than 450 kgs
FCOM, VOL 2; 12.30.1
What does a visible bar indication mean for Crossfeed Valve Switches 2 and 3?
• Crossfeed valve open when commanded by system logic.
FCOM, VOL 2; 12.10.1
What does a Visible bar indication mean for Crossfeed Valve Switches 1 and 4?
• The crossfeed valve is open.
FCOM, VOL 2; 12.10.2
What does it mean when the main tank 2 and 3 Override (OVRD) Fuel Pump Switches are ON? How about OFF, ON not visible?
• ON – fuel pump operates when commanded by system logic.
• OFF (ON not visible) – fuel pump selected OFF.
FCOM, VOL 2; 12.10.2
What is shared flow?
- When CWT drops below 2300kgs,fuel consumption is greater than
6800 kg/hr, the CWT OJP’s can no longer provide full override of the
outboard main tank pumps. - This sets up a shared flow situation which allows approximately
900kgs to be used from tanks 1 and 4, prior to EICAS message
FUEL LOW CENTRE.
What is the stand pipe level during override and jettison operation?
- 3200 kgs.
In climb, how much fuel in the CWT will activate FUEL LOW CTR L,R?
- Approximately 3200 kgs.
Before start with CWT pumps switches ON, what tank quantity will
activate FUEL LOW CTR L,R?
- CWT quantity less than 7700 kgs.
In cruise and on the ground, what quantity in the centre tank will bring the advisory message FUEL OVD CTR L,R?
- 1800 kgs or more in the CWT with centre wing tank pump switches OFF.
- 7700 kgs or more with the centre wing tank pumps OFF.
