B767
Fuel DO NOT USE FOR FLIGHT
Boeing B767 - Systems Summary [Fuel]
Introduction The fuel system supplies fuel to the engines and the APU. The fuel is contained in a center tank, and left and right main tanks. Refer to Chapter 7, Engines, APU, for an additional description of the engine and APU fuel systems.
Fuel Quantity Fuel quantity data, measured by probes in each tank, is fed to the fuel quantity processor where it is corrected for density then displayed on a fuel quantity indicator for each tank. Total fuel quantity, from a separate calculation, is shown on the total fuel quantity indicator and is also provided to the FMC. When total usable fuel in either left or right main tank drops below approximately 2200 pounds, the FUEL CONFIG light illuminates and the LOW FUEL caution message is displayed.
Fuel Temperature Temperature of the fuel in the left main tank is displayed on the fuel temperature indicator.
Fuel Pumps Each fuel tank contains two AC–powered fuel pumps. A single pump can supply sufficient fuel to operate one engine under all conditions. The two center tank fuel pumps have greater output pressure than the left and right main tank fuel pumps. When all six pumps are operating, the center tank pumps override the left and right main tank pumps so that center tank fuel is used before left or right main tank fuel. If any pump has low output pressure, the appropriate switch PRESS light illuminates and the pump pressure EICAS message is displayed. If the main tank pump switches are OFF, the low pressure lights are illuminated and EICAS messages for the pumps are displayed. When the center pump switches are OFF, the low pressure lights and EICAS messages for the center pumps are inhibited. To reduce electrical loads, the center tank pumps are inhibited when the associated N2 is less than 50% RPM. Thus both center tank pumps are inhibited when the engines are shutdown. As an engine is started and N2 RPM increases above 50%, the inhibit is removed for the associated center tank pump.
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Boeing B767 - Systems Summary [Fuel]
The EICAS caution messages, L or R FUEL SYS PRESS, displays when all fuel pumps have low output pressure or all fuel pumps on one side have low output pressure and the crossfeed switches are off. The fuel pump low pressure messages are inhibited by the corresponding L or R FUEL SYS PRESS messages. During normal operation, the EICAS advisory messages CTR L FUEL PUMP and CTR R FUEL PUMP display to indicate depletion of center tank fuel. With either message displayed, a small amount of center tank fuel may be indicated. A scavenge system will operate automatically to transfer any remaining center tank fuel to the main tanks. Fuel scavenge begins when the main tanks are approximately half empty. The left main tank contains a DC–powered fuel pump. It has no controls or indicators. The DC pump operates automatically to provide fuel to the APU when AC power is not available and the APU selector is ON.
Fuel Crossfeed The fuel manifolds are arranged so that any fuel tank pump can supply either engine. Two crossfeed valves isolate the left fuel manifold from the right. These valves are normally closed providing fuel feed from tank to engine. Both valves are opened any time it becomes necessary to feed an engine from an opposite fuel tank. Only one open crossfeed valve is required for successful crossfeed operation. A valve disagreement light illuminates and the EICAS advisory message FWD FUEL X–FEED or AFT FUEL X–FEED displays if a valve position does not agree with its switch position. The L or R FUEL SYS PRESS messages are inhibited with either crossfeed valve open.
Suction Feed When main tank fuel pump pressure is low, each engine can draw fuel from its corresponding main tank through a suction feed line that bypasses the pumps. As the airplane climbs, dissolved air is released from the fuel in the tank due to the decrease in air pressure. This air may collect in the suction feed line and restrict fuel flow. At high altitude, thrust deterioration or engine flameout may occur as a result of the fuel flow reduction. Fuel pressure can be provided from a main tank with operating fuel pumps to both engines by opening the fuel crossfeed valves. Continued crossfeed use will result in a progressive fuel imbalance. The dissolved air in the fuel tank will eventually deplete after reaching cruise altitude. The depletion time is dependent upon airplane altitude, fuel temperature, and type of fuel. Once the dissolved air is depleted, the engine may be capable of suction feed operation at cruise power. Page 2
Boeing B767 - Systems Summary [Fuel]
Fuel Configuration Light When the fuel quantity in left and right main tanks differ by 2000 pounds (plus or minus 500 pounds) or center fuel pump switches are OFF with more than 1200 pounds in the center tank, the FUEL CONFIG light illuminates and the EICAS advisory message FUEL CONFIG is displayed. The FUEL CONFIG light also illuminates when the EICAS caution message LOW FUEL is displayed.
Fuel Imbalance Fuel balancing is accomplished by opening the crossfeed valves and turning off the fuel pump switches for the left or right main fuel tank that has the lowest quantity. Fuel balancing may be done in any phase of flight.
Fuel Tank Locations and Capacities Fuel Tank Locations RIGHT MAIN TANK
CENTER TANK LEFT MAIN TANK
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Boeing B767 - Systems Summary [Fuel]
Fuel Tank Capacities Tank
U.S. Gallons
Pounds *
Left main
6,010
40,267
Right main
6,010
40,267
Center
11,900
79,730
23,920
160,264
Total
* Usable fuel at level attitude, fuel density = 6.7 LB/U.S. per Gallon
Total
Tank
U.S. Gallons
Pounds *
Left main
6,010
40,267
Right main
6,010
40,267
Center
11,960
80,132
23,980
160,666
* Usable fuel at level attitude, fuel density = 6.7 LB/U.S. per Gallon
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Boeing B767 - Systems Summary [Fuel]
Fuel System Schematic
L PUMPS AFT
FWD
FUEL XFEED
ON PRESS
VALVE
ON PRESS
VALVE
C PUMPS L
ON
P R E S S
ENGINE VALVE
SPAR VALVE
CENTER
CROSSFEED VALVES LEFT MAIN
DC APU FUEL VALVE
APU
APU Fuel Feed APU fuel is supplied from the left fuel manifold. APU fuel can be provided by any AC fuel pump supplying fuel to the left fuel manifold or by the left main tank DC fuel pump.
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Boeing B767 - Systems Summary [Fuel]
On the ground, with the APU selector ON and no AC power available, the DC pump runs automatically. With AC power available, the left forward AC fuel pump operates automatically, regardless of fuel pump switch position, and the DC fuel pump turns off.
Fuel Jettison The fuel jettison system allows jettison from the center fuel tank. Fuel is jettisoned through nozzles inboard of each outboard aileron. The common fuel manifold allows jettison pumps in the center tank to pump fuel overboard. Two dual pump units provide a high capacity jettison rate of approximately 2600 pounds per minute. Fuel jettison begins when: • the FUEL JETTISON selector is selected ON • the jettison transfer valves open • the FUEL JETTISON NOZZLE switches are selected ON • the nozzle valves open, and • the jettison pumps operate The FMC discontinues fuel value calculations and the totalizer value is used during fuel jettison operation. After fuel jettison is complete, the calculated value will reset using the same value as the totalizer value. The fuel disagree message is not displayed during fuel jettison operation.
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Boeing B767 - Systems Summary [Fuel]
Fuel Jettison Schematic
CENTER TANK
LEFT MAIN TANK
TO ENGINES OUTER MAIN (LEFT)
NOZZLE VALVE JETTISON TRANSFER VALVES CENTER/ JETTISON PUMPS
FUEL JETTISON L-NOZZLE-R ON
ON
VALVE
VALVE
FAULT
OFF
ON
Fuel System FMS CDU Messages The CDU can display the following messages. INSUFFICIENT FUEL – Predicted fuel at destination is less than the FMC reserves FUEL DISAGREE–PROG 2 – The fuel totalizer and calculated fuel quantity disagree
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Boeing B767 - Systems Summary [Fuel]
Fuel System EICAS Messages The following EICAS messages can be displayed. Message
Level
Light
FUEL CONFIG
Advisory
FUEL CONFIG
Both center pump switches are OFF with fuel in the center tank or a fuel imbalance between main tanks
AFT FUEL X-FEED
Advisory
VALVE
The crossfeed valve position disagrees with the commanded position
Advisory
VALVE
In flight, the nozzle valve position disagrees with the commanded position
FWD FUEL X-FEED FUEL JET NOZ
Aural
Condition
On the ground indicates one or both fuel nozzle valves are open L FUEL JET PUMP
Advisory
FAULT
The associated fuel jettison pump is inoperative
Advisory
FAULT
The associated fuel jettison transfer valve is not in the commanded position
Advisory
PRESS
Fuel pump output pressure is low
R FUEL JET PUMP L JET XFER VALVE R JET XFER VALVE
CTR L FUEL PUMP CTR R FUEL PUMP L AFT FUEL PUMP R AFT FUEL PUMP L FWD FUEL PUMP R FWD FUEL PUMP
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Boeing B767 - Systems Summary [Fuel]
Message L FUEL SYS PRESS
Level
Light
Caution
Aural
Condition
Beeper
All fuel pumps have low output pressure or all fuel pumps on one side have low output pressure and the crossfeed switches are off
Beeper
Fuel quantity is low in either left or right main tank
R FUEL SYS PRESS
LOW FUEL
Caution
FUEL CONFIG
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Boeing B767 - Systems Summary [Fuel]
Fuel System L PUMPS 1 2
AFT
FWD
ON
ON
PRESS
VALVE
PRESS
ON
ON
PRESS
VALVE
PRESS
L
P R E S S
P R E S S
AFT
FWD 5
C PUMPS ON
4
R PUMPS
FUEL XFEED
FUEL CONFIG ON
6
R
3
OVERHEAD PANEL 1
Left/Center/Right (L/C/R PUMPS) Switches
ON – the fuel pump is selected ON Off (ON not visible) – the fuel pump is selected off 2
Left/Right Pump Pressure (PRESS) Lights
Illuminated (amber) – fuel pump output pressure is low 3
Center Pump Pressure (PRESS) Lights
Illuminated (amber) – • fuel pump output pressure is low with the pump selected ON • associated N2 below 50% with pump switch ON Note: Illumination is inhibited when the center tank fuel pump switch is selected OFF. 4
Fuel Crossfeed (FUEL XFEED) Switches
On (bar visible) – the crossfeed valve is selected open Off (bar not visible) – the crossfeed valve is selected closed
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Boeing B767 - Systems Summary [Fuel] 5
Crossfeed VALVE Light
Illuminated (amber) – the crossfeed valve is not in the selected position 6
Fuel Configuration (FUEL CONFIG) Light
Illuminated (amber) – • low fuel quantity • imbalance between left and right main tanks • center tank fuel pumps off with fuel in center tanks
Fuel Indications Fuel Quantity Indicator
C
L
R
1 LB
LB
LB
FUEL QTY
2
X 1000
TEMP
oC
3 TOTAL
OVERHEAD PANEL
1
Fuel Quantity (L/C/R FUEL QTY) Indication
Displays usable fuel quantity in the left main, center, and right main tank (pounds x 1000) 2
Fuel Temperature (TEMP) Indication
Displays temperature of fuel in the left main tank (degrees celsius) 3
TOTAL Fuel Quantity Indication
Displays total usable fuel quantity in all tanks (pounds x 1000)
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Boeing B767 - Systems Summary [Fuel]
Fuel Jettison
FUEL JETTISON L-NOZZLE-R 1
ON
ON
2
VALVE
VALVE
FAULT
OFF
3
ON 4
OVERHEAD PANEL
1
Fuel Jettison Nozzle Switches (L–NOZZLE–R)
ON – opens respective jettison nozzle Off (ON not visible) – closes respective jettison nozzle 2
Fuel Jettison Nozzle VALVE Lights
Illuminated (amber) – the jettison nozzle valve is not in the selected position 3
FAULT Light
Illuminated (amber) – jettison pump(s) and/or transfer valve(s) disagree with jettison switch position 4
Fuel Jettison Selector
OFF – closes both jettison transfer valves and turns off jettison pumps ON – opens both jettison transfer valves and turns on jettison pumps
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Boeing B767 - Systems Summary [Fuel]
Fuel Quantity Test
1
FUEL QTY ACCESSORY PANEL 1
Fuel Quantity (FUEL QTY) Test Switch
Spring–loaded to center Initiates fuel quantity test
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