Fuel Flashcards
EICAS color indications of fuel pump status
White - pump off
Green - pump on
Amber - pump low pressure
How many fuel tanks?
- 4 x main tanks (1,2,3,4)
- center wing tank
- 2 x reserve tanks (2,3)
- surge tanks in outer portion of each wing
- horizontal stab tank with surge tank in outboard portion (pax)
How many fuel pumps?
- 8 x AC powered main tank pumps (2 per main tank)
- 4 x AC powered override/jettison pumps (2 each for main tank 2 and 3)
- 2 x Center Wing Tank (CWT) pumps (override/jettison)
Main and Override pump pressure capability
Main Pumps
- each pump can provide enough fuel for 1 engine during TO or 2 engines during cruise
Override/Jettison Pumps
- each pump can provide enough fuel for 2 engine during TO and cruise
- higher output than main pumps
- center wing pumps are Override/Jettison pumps
- horizontal stab tank pumps are override/jettison pumps (Pax)
Fuel Tank Capacities
Main 1 and 4: 26,576 kg (13.3 ea) Main 2 and 3: 76,263 kg (38.1 ea) Center: 52,167 kg Reserves: 8,036 kg (4.0 ea) Stab Tank (pax): 10,030 kg
Total (freight): 163,042 kg
Total (pax): 173,072 kg
When does fuel transfer from Reserve Tanks to Main tanks 2 or 3?
- each reserve tank has two transfer valves
- via gravity fuel transfers when main tank 2 or 3 drop below 18,200 kg
- transfer valves can be open manually (RSV 2 and 3 XFER) or automatically by system logic
Which tank is normal/backup source for APU fuel?
- Main tank 2 supplied by main pump 2 aft
- Bankup is Main pump 3 aft
- DC pump in main tank 2 for APU battery start
How is fuel system logic managed?
2 x Fuel System Management Cards (FSMCs) command fuel valves and pumps open or closed
How is fuel jettisoned from the tanks?
- Fuel Jettison selector rotated out of OFF position
- Jettison Nozzle Valve On
- Override/Jettison pumps (Main 2 and 3, CWT) pump fuel from all fuel tanks overboard
What causes a FUEL IMBALANCE EICAS message?
- imbalance between Main 1 and 4 of 1,360 kg
- imbalance between Main 2 and 3 of 2,720 kg
- message is removed when difference less than 450 kg
How is Fuel Quantity and Fuel Temperature measured?
- Fuel Quantity sensor in each tank
- Fuel Temp sensors in main tank 1
How is fuel flow displayed in the Fuel Synoptic page
- Fuel flow is simulated based upon the pump status and valve positions
- may no represent actual system operation
How is fuel management controlled?
2 x Fuel System Management Cards (FSMCs)
- fuel valves open or closed based on logic
- fuel pumps ON or OFF based on logic
Which fuel pumps are on with the APU Running prior to engine start?
Main tanks 2 and 3 (PRESS light will be off)
How many surge tanks per wing?
- one surge tank per wing
- provide fuel surge relief and tank venting
- no controls or indications to flight crew
How many Fuel Crossfeed Valves
- 4 x Fuel Crossfeed Valves in fuel manifold
- fuel can be delivered from any Main Tank or CWT to any engine or APU
Where is the Defuel Panel located?
- overhead maintenance panel
- not normally used by flight crew
Scavenge System
- 4 scavenge pumps in CWT
- ensure all fuel from CWT to Main Tanks 2 and 3
- no control or indications
- begins when main tank 2 or 3 decrease to approx 27,200 kgs
How is Fuel Balanced between tanks?
- opening and closing of Crossfeed valves
- turning ON or OFF of specific pumps
Where is Fuel system information displayed?
- Primary EICAS
- FUEL synoptic page
Color indications for pumps on FUEL synoptic page?
White - OFF
Green - ON
Amber - Low Press
Cyan - Armed for System logic (override pumps)
What would cause Fuel Main tank quantity to display in Amber?
- imbalance condition
- less than 900 kg (2000 lbs)
Fuel Density of usable fuel at level attitude
0.8 kgs per liter
How much capacity can each AC Main pump support?
- one engine at Takeoff Thrust; or
- two engines at cruise thrust
How much capacity can each override/jettison support?
- two engines at takeoff or cruise thrust
What fuel quantity can override/jettison pumps 2 and 3 operate until?
Until standpipe level of approx 3,200 kg (7,000 lbs)
- avoids jettison of all fuel
Which pumps have priority over all others?
CWT override/jettison pumps override all other pumps
- OJPs 2 and 3 are inhibited
- One CWT pump will not inhibit or override
Can engine receive fuel if fuel pump pressure is low?
- Suction feed line to each engine, which bypasses fuel pumps
- at hight altitudes reduced thrust or engine flameout may occur (dissolved air restricting fuel flow)
How is each fuel pump activate?
Main pumps - manually via Main pump switch ON
Override/jettison pumps - system logic with switch ON
When does fuel transfer from Main tanks 1 and 4 to Main tanks 2 and 3?
- one transfer valve in each of Main tank 1 and 4
- not a normal operation
- Manually via FUEL XFER MAIN 1 and 4
- automatically during fuel jettison when 2 and 3 tanks drop below 9,072 kg
- fuel transfers via gravity
- transfers to approx 3,200 kg in each outboard main tank
When should the CWT pump switches be ON during normal flight ops?
When CWT has 7,700 kgs or more of fuel
> FUEL TANK/ENG EICAS message
- Fuel in main tank 2 is equal or less than main tank 1
- Fuel in main tank 3 is equal or less than main tank 4
Actions:
1) Manually turn #2 and #3 OVRD pumps OFF
2) Manually CLOSE cross feeds #1 and #4
Which pumps provide jettison fuel pressure?
- override/jettison pump 2 and 3 and CWT OJPs
When is Fuel Jettison prohibited?
With flaps in TRANSIT between 1 and 5
How many jettison control systems?
2 (A or B)
What kind of fuel supply?
Tank to engine
When does fuel temperature indication turn amber?
-37º C and below
Which tanks is fuel jettisoned from?
All tanks via Main tanks 2 and 3 and CWT
What EICAS indication do you get when FUEL JETTISON selector is out of OFF (A or B)
Fuel to remain (TO REMAIN) replaces fuel temp
With fuel tanks full what pumps are supplying engine during start?
Both Center Wing OJPs
Fuel Pump/Cross-feed valve configuration with Flaps Set for Takeoff (Center tank over 7,700 kg of fuel)
CWT pumps ——> Engines 1 and 4
Main pumps 2 ——> Engine 2
Main pump 3 ——> Engine 3
Cross-feed valves 2 and 3 ——>closed
Fuel Pump/Cross-feed valve configuration with Flaps Set for Takeoff (Center tank less than 7,700 kg of fuel)
Override/jettison pump 2 ——> engine 1 Override/jettison pump 3 ——> engine 4 Main pump 2 ——> engine 2 Main pump 3 ——> engine 3 Cross-feed valves 2 and 3 ——> closed
Fuel Pump/Cross-feed valve configuration with Flaps Up after Takeoff (Center Tank On)
CWT Override/Jettison pumps ——> all engines
All cross-feed valves ——> open
Fuel Pump/Cross-feed valve configuration with Flaps Up after Takeoff (Center tank pumps off)
Override/jettison pumps 2 ——> ENG 1 and 2
Override/jettison pumps 3 ——> ENG 3 and 4
Cross-feed valves 2 and 3 ——> Open
FUEL LOW CTR L, R EICAS Message
- CWT less than 7,700 kgs before start with pump ON
- CWT approx 3,200 kg in climb with pump ON
- CWT approx 1,300 kg in cruise with pump ON
What happens to the fuel quantity indication upon termination of fuel jettison?
- fuel to remain changes colors from magenta to white and flashes for 5 secs
What is the impact of an excessive fuel imbalance on the aircraft?
Adversely affects:
- CG
- aerodynamic drag
- fuel economy
When is an engine on suction feed, and how are suction feed situation corrected?
- suction feed begins when main tank pressure is low
- corrected by opening appropriate cross-feed valves to obtain pressure from a main tank with operations pumps
