b737-300/400 fuel

of 83PT. METRO BATAVIAPT. METRO BATAVIADirectorate of OperationalDirectorate of Operational

737-300/400737-300/400FUELFUEL

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737-300/400 Fuel Schematic

To APU

APU fuelshutoffvalveAPU bypass

valve

Bypassvalve

No. 1fuel tank

No. 1engine

No. 2engine

Engine drivenfuel pump

BypassvalveCenter fuel tank

No. 2fuel tank

Engine fuelshutoff valve



Manual defueling valve

Center left pump

Center right pump

No. 2 fwdpump

No. 2 aftpump

Center right pump inlet

Center left pump inletNo. 1 fwd

pump

No. 1 aftpump

Fueling receptacle

When pulled,closes No. 1 engine

fuel shutoff valve


fuel shutoff valve

Fuel temperatureindicator

Pressure fuelingstation

Surge tankSurge tank

Crossfeed valve

Scavengevalve

Scavengeinlet

Center tankscavenge jet

pump

Fuel shutoffvalves (3)



No. 1fuel tank Center fuel tank

No. 2fuel tank

There are three fuel tanks: No. 1, Center, and No. 2. The No. 1 and No. 2 fuel tanks are located in the interspar area of each wing. The center fuel

tank is contained in the fuselage (wing center section).




No. 2fuel tank

A pressure fueling station is installed on the right wing leading edge. A fueling receptacle allows a hose to be connected for fueling. Shutoff valves control fuel distribution to the tanks.

Fueling receptacle


No. 2fuel tank

Center fuel tankNo. 1

fuel tank




One surge tank can be found outboard of each wing fuel tank. Vent channels allow the surge tanks to collect any fuel overflow from the main tanks. A surge tank drain line then allows the fuel overflow to drain back into the center tank, but

prevents fuel flow from the center tank to the surge tank. Each surge tank has a capacity of approximately 30 U.S. gallons.



No. 2fuel tank

No. 2fuel tank


fuel tank

Fueling receptacle





A fuel vent scoop is located on each outboard lower wing surface, under the surge tank. The scoops create positive pressure during flight and are the overboard vents for the vent system. If a significant amount of overflow fuel is collected in a surge

tank, the fuel will be discharged overboard via the vent scoops. The scoops are designed to prevent ice accumulation.

See picture of See picture of fuel vent scoopfuel vent scoop


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle





The No. 1 fuel tank contains a forward and aft fuel boost pump. Each pump is AC powered and is fuel cooled and lubricated. The forward pump is attached to the forward wing spar and the aft pump is installed in a dry bay within the fuel tank. The wing spar and dry bay isolate the pump motor from the fuel in the tank.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle



No. 1 fwdpump

No. 1 aftpump



Fuel from the tank enters each pump through a wire mesh screen via a suction tube inlet. Fuel is discharged from the pump under pressure through the boost pump check valve. The check valves are located inside the fuel tank and will open when respective fuel pump pressure is approximately 12 psi.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle



No. 1 fwdpump

No. 1 aftpump



The No. 1 tank fuel LOW PRESSURE lights will illuminate when the respective fuel pump switch is ON and fuel boost pump pressure is low. The LOW PRESSURE

lights will also illuminate when the respective fuel pump switch is OFF.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump






fuel shutoff valve

Prior to fuel entering the No. 1 engine, it must first pass through the engine fuel shutoff valve. The valve is electrically (DC) opened when the No. 1 engine start lever is positioned from CUTOFF to IDLE. The valve closes when

the start lever is lowered from IDLE to CUTOFF. The valve also closes when the No. 1 engine fire switch is pulled.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




From the engine fuel shutoff valve, fuel is delivered to the No. 1 engine via the main engine control (MEC).

No. 1engine


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump



fuel shutoff valve




A bypass valve allows fuel to be drawn out of the tank by an engine driven fuel pump. This would only occur if both No. 1 fuel tank pumps were to

fail. The engine driven fuel pump is attached to the engine gearbox.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump



fuel shutoff valveNo. 1

engine


Bypassvalve




A fuel temperature sensor is located in the No. 1 fuel tank. The fuel temperature indicator displays the results in °C.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve






The No. 2 fuel tank contains a forward and aft fuel boost pump. Each pump is AC powered and is fuel cooled and lubricated. The forward pump is attached to the forward wing spar and the aft pump is installed in a dry bay within the fuel tank. The wing spar and dry bay isolate the pump motor from the fuel in the tank.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve




No. 2 fwdpump

No. 2 aftpump



Fuel from the tank enters each pump through a wire mesh screen via a suction tube inlet. Fuel is discharged from the pump under pressure through the boost pump check valve. The check valves are located inside the fuel tank and will open when respective fuel pump pressure is approximately 12 psi.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve




No. 2 fwdpump

No. 2 aftpump



The No. 2 tank fuel LOW PRESSURE lights will illuminate when the respective fuel pump switch is ON and fuel boost pump pressure is low. The LOW PRESSURE

lights will also illuminate when the respective fuel pump switch is OFF.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve


Fuel temperatureindicator No. 2 fwd

pump

No. 2 aftpump






fuel shutoff valve

Prior to fuel entering the No. 2 engine, it must first pass through the engine fuel shutoff valve. The valve is electrically (DC) opened when the No. 2 engine start lever is positioned from CUTOFF to IDLE. The valve closes when

the start lever is lowered from IDLE to CUTOFF. The valve also closes when the No. 2 engine fire switch is pulled.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




From the engine fuel shutoff valve, fuel is delivered to the No. 2 engine via the main engine control (MEC).

No. 2engine


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump



fuel shutoff valve




A bypass valve allows fuel to be drawn out of the tank by an engine driven fuel pump. This would only occur if both No. 2 fuel tank pumps were to

fail. The engine driven fuel pump is attached to the engine gearbox.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump



fuel shutoff valve No. 2engine


Bypassvalve




The DC powered crossfeed valve connects the left and right fuel manifold. It provides a means of directing fuel to either engine from any tank.

Crossfeed valve


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve





The center fuel tank utilizes the left and right fuel boost pump. Each pump is AC powered and is fuel cooled and lubricated. The center left pump is installed in a dry bay within the No. 1 fuel tank. The center right pump is installed in a dry bay within the No. 2 fuel tank. The dry bay isolates the pump motor from the fuel in the tank.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve


Center left pump

Center right pump



Fuel from the center tank enters each pump through a wire mesh screen via a suction tube inlet. Fuel is discharged from the pump under pressure through the boost pump check valve. The check valves are located inside the fuel tank and will open when respective fuel pump pressure is approximately 1.3 psi.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve


Center left pump inlet


Center left pump

Center right pump



As previously stated, the main tank and center tank check valves open at a boost pump pressure of approximately 12 and 1.3 psi, respectively. Therefore, assuming fuel in all three tanks and all six pumps operating, fuel is delivered to the engines from the center tank first due to the lower “cracking” pressure of the check valves.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump




The center tank fuel LOW PRESSURE lights will illuminate when the respective fuel pump switch is ON and fuel boost pump pressure is low. The LOW PRESSURE

lights will extinguish when the respective fuel pump switch is OFF.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump




A center tank fuel scavenge system is installed to drain unusable fuel from the center tank into the No. 1 tank. This occurs when both center tank pump switches are positioned to OFF. This action sends an electrical signal to the scavenge valve to open for a time period of 20 minutes.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump


Scavengeinlet

Scavengevalve


pump



With the scavenge valve now open, fuel from the No. 1 fwd pump flows to the center tank scavenge jet pump. This results in low pressure being created in the scavenge inlet. Remaining fuel in the center tank is now drawn out and drained into the No. 1 tank. The scavenge valve will close

at the end of 20 minutes. The scavenge valve may be re-opened, for 20 minutes, by cycling the center pump switches to ON and back OFF.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump

Scavengeinlet

Scavengevalve


pump




Fuel may be delivered to the APU from any one of the three tanks. The APU fuel shutoff valve controls delivery of fuel to the APU. The valve is opened and closed by the APU

start switch. Pulling the APU fire switch will also close the APU fuel shutoff valve.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump

Scavengeinlet

Scavengevalve


To APU

APU fuelshutoffvalve


pump



With no AC power available to the aircraft, all six fuel pumps are inoperative. If attempting to start the APU with no AC power on the aircraft, the fuel pumps are not available to feed fuel to the APU. Therefore, an APU bypass valve is located in the No. 1 fuel tank which allows fuel to be drawn out of the tank for APU operation. The APU cannot draw fuel out of the No. 2 or center tank.


No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump

Scavengeinlet

Scavengevalve

To APU



pump


APU bypassvalve



The manual defueling valve is located inboard of the pressure fueling station on the right wing front spar. It controls fuel flow from the fuel manifold to the pressure fueling station. It is used to defuel any one of the three tanks, or to transfer fuel from tank to tank (on the ground

only). The handle of the defueling valve is such that its access door cannot be closed when the defueling valve is in the open position.



No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump

Scavengeinlet

Scavengevalve

To APU



pumpAPU bypassvalve




Although not shown in the schematic above, overwing fill ports (for gravity fueling) are provided for the No. 1 and No. 2 fuel tanks. These receptacles would be utilized if pressure fueling facilities are not available. If fuel is desired in the center tank during this type of scenario, fuel must be transferred from the main tanks via the manual defueling valve.



No. 2fuel tank

No. 2fuel tank


fuel tank


Fueling receptacle


No. 1 fwdpump

No. 1 aftpump




engine

Bypassvalve



pump

No. 2 aftpump




Bypassvalve


Crossfeed valve



Center left pump

Center right pump

Scavengeinlet

Scavengevalve

To APU



pumpAPU bypassvalve


This concludes the review of the Fuel Schematic. The next section This concludes the review of the Fuel Schematic. The next section will discuss various fueling related panels. Click will discuss various fueling related panels. Click NextNext to continue. to continue.


Fuel Control PanelFuel Control Panel

Forward Overhead PanelForward Overhead Panel


Fuel Control PanelFuel Control PanelFUEL VALVE CLOSED lights:FUEL VALVE CLOSED lights:Illuminated Illuminated brightbright blue – blue –• Related engine fuel shutoff valve in transit.Related engine fuel shutoff valve in transit.• Related engine fuel shutoff valve position Related engine fuel shutoff valve position

disagrees with start lever or engine fire warning disagrees with start lever or engine fire warning switch position.switch position.

Illuminated Illuminated dimdim blue – blue –• Related engine fuel shutoff valve is closed.Related engine fuel shutoff valve is closed.

Extinguished –Extinguished –• Related engine fuel shutoff valve is open.Related engine fuel shutoff valve is open.


Fuel Control PanelFuel Control PanelFUEL TEMP Indicator:FUEL TEMP Indicator:Indicates fuel temperature in the No. 1 Indicates fuel temperature in the No. 1 fuel tank only.fuel tank only.


Fuel Control PanelFuel Control PanelFILTER BYPASS Lights:FILTER BYPASS Lights:Illuminated –Illuminated –Impending fuel filter bypass on respective engine Impending fuel filter bypass on respective engine due to a contaminated filter. due to a contaminated filter.

Note: During a FILTER BYPASS, fuel is routed Note: During a FILTER BYPASS, fuel is routed around the filter and delivered to the engine around the filter and delivered to the engine unfiltered.unfiltered.


Fuel Control PanelFuel Control PanelCROSSFEED Selector:CROSSFEED Selector:Controls fuel crossfeed valve.Controls fuel crossfeed valve.

Open –Open –Connects left and right fuel manifold.Connects left and right fuel manifold.

Closed –Closed –Isolates left and right fuel manifold.Isolates left and right fuel manifold.


Fuel Control PanelFuel Control PanelCrossfeed VALVE OPEN light:Crossfeed VALVE OPEN light:Illuminated Illuminated brightbright blue – blue –• Crossfeed valve in transit.Crossfeed valve in transit.• Crossfeed valve and CROSSFEED selector Crossfeed valve and CROSSFEED selector

disagree.disagree.

Illuminated Illuminated dimdim blue – blue –• Crossfeed valve is open.Crossfeed valve is open.

Extinguished –Extinguished –• Crossfeed valve is closed.Crossfeed valve is closed.


Fuel Control PanelFuel Control PanelCTR Tank Fuel Pump Switches (L and R):CTR Tank Fuel Pump Switches (L and R):ON –ON –Activates respective center tank fuel pump.Activates respective center tank fuel pump.

OFF –OFF –Deactivates respective center tank fuel pump.Deactivates respective center tank fuel pump.


Fuel Control PanelFuel Control PanelCenter Tank Fuel Pump LOW PRESSURE Lights:Center Tank Fuel Pump LOW PRESSURE Lights:Illuminated –Illuminated –Respective fuel pump switch is ON and output Respective fuel pump switch is ON and output pressure is low.pressure is low.

Extinguished –Extinguished –• Respective fuel pump switch is ON and output Respective fuel pump switch is ON and output

pressure is normal.pressure is normal.• Respective fuel pump switch is OFF.Respective fuel pump switch is OFF.


Fuel Control PanelFuel Control PanelMain Tank Fuel Pump Switches (FWD and AFT):Main Tank Fuel Pump Switches (FWD and AFT):ON –ON –Activates respective main tank fuel pump.Activates respective main tank fuel pump.

OFF –OFF –Deactivates respective main tank fuel pump.Deactivates respective main tank fuel pump.


Fuel Control PanelFuel Control PanelMain Tank Fuel Pump LOW PRESSURE Lights:Main Tank Fuel Pump LOW PRESSURE Lights:Illuminated –Illuminated –• Respective fuel pump switch is ON and output Respective fuel pump switch is ON and output

pressure is low.pressure is low.• Respective fuel pump switch is OFF.Respective fuel pump switch is OFF.

Extinguished –Extinguished –• Respective fuel pump switch is ON and output Respective fuel pump switch is ON and output

pressure is normal.pressure is normal.


Fuel Quantity IndicationsFuel Quantity Indications

Instrument PanelsInstrument Panels


Fuel Quantity IndicationsFuel Quantity IndicationsFuel Quantity Indicators:Fuel Quantity Indicators:• Indicates total weight of usable fuel in Indicates total weight of usable fuel in respective respective tank.tank.• AC standby power is required.AC standby power is required.• Segmented arc indicates fuel quantity as a Segmented arc indicates fuel quantity as a

percentage of fuel capacity.percentage of fuel capacity.

Note: There are many different types of fuel Note: There are many different types of fuel quantity indicators. The type installed in your quantity indicators. The type installed in your aircraft may not necessarily match the type aircraft may not necessarily match the type discussed in this presentation. The type shown discussed in this presentation. The type shown here is manufactured by Simmondshere is manufactured by Simmonds®.®.


Fuel Quantity IndicationsFuel Quantity IndicationsERR Indicator:ERR Indicator:• ERR appears with associated error codes (0-9) ERR appears with associated error codes (0-9)

whenever a malfunction occurs.whenever a malfunction occurs.• Used for maintenance purposes onlyUsed for maintenance purposes only


Fuel Quantity IndicationsFuel Quantity IndicationsFuel QTY TEST Switch:Fuel QTY TEST Switch:Press and hold –Press and hold –• Fuel quantity indicators display a value of “0”.Fuel quantity indicators display a value of “0”.• ““ERR 4” is shown.ERR 4” is shown.

When switch is released, a self test is initiated –When switch is released, a self test is initiated –• All segments of the indicators display for two All segments of the indicators display for two

seconds.seconds.• All segments of the indicators extinguish for All segments of the indicators extinguish for two two seconds.seconds.• Indicators display full tank capacity and stored Indicators display full tank capacity and stored

error codes, if any, for two seconds.error codes, if any, for two seconds.• Indicators return to actual fuel quantity.Indicators return to actual fuel quantity.


Measurement/Fueling/Defueling

Dripstick(five on each wing)

Pressure fueling station

Defueling valve

See picture of See picture of fuel tank access panelfuel tank access panel

and dripstick headand dripstick head


Measurement/Fueling/DefuelingFuel Measuring Stick:Fuel Measuring Stick:• Utilized to measure fuel quantity in the No. 1 and Utilized to measure fuel quantity in the No. 1 and

No. 2 fuel tanks. No dripsticks associated with No. 2 fuel tanks. No dripsticks associated with the center fuel tank.the center fuel tank.• Allows a comparison of fuel weight (as indicated Allows a comparison of fuel weight (as indicated

by the fuel quantity indicators) to the value by the fuel quantity indicators) to the value shown on the measuring sticks to ensure the shown on the measuring sticks to ensure the indicators are operating normally.indicators are operating normally.• Five sticks installed on each main tank.Five sticks installed on each main tank.• Reading is obtained by turning the head of the Reading is obtained by turning the head of the

dripstick 90dripstick 90° in a counter-clockwise direction. ° in a counter-clockwise direction. Slowly lower the stick until fuel begins to “drip” Slowly lower the stick until fuel begins to “drip” from the hole located near the bottom of the from the hole located near the bottom of the stick. Quantity may now be determined by stick. Quantity may now be determined by reading the measuring units on the stick. This reading the measuring units on the stick. This procedure is best performed by trained procedure is best performed by trained

maintenance personnel. maintenance personnel.


Measurement/Fueling/DefuelingPressure Fueling Station:Pressure Fueling Station:• Provides all the necessary switches, Provides all the necessary switches, indicators, and valves to quickly fuel all three indicators, and valves to quickly fuel all three

tanks.tanks.• Located on right wing, aft of leading edge Located on right wing, aft of leading edge

slats.slats.


Fueling Receptacle:Fueling Receptacle:Connects the fueling hose to the pressure Connects the fueling hose to the pressure fueling system.fueling system.

Measurement/Fueling/Defueling


Measurement/Fueling/DefuelingFueling Shutoff Valves:Fueling Shutoff Valves:• Controls fuel distribution to their respective Controls fuel distribution to their respective tank.tank.• Electrically (DC) activated.Electrically (DC) activated.• Solenoid actuated, spring-loaded to the closed Solenoid actuated, spring-loaded to the closed

position.position.

Left-half of pressure fueling stationLeft-half of pressure fueling station


Measurement/Fueling/DefuelingManual Override Push Buttons Manual Override Push Buttons (Solenoid Override)(Solenoid Override)::• Utilized if DC power is not available to the Utilized if DC power is not available to the fueling fueling shutoff valves.shutoff valves.• Mechanically opens shutoff valve when fuel Mechanically opens shutoff valve when fuel

pressure pressure is supplied.is supplied.



Measurement/Fueling/DefuelingFueling Power Control Switch:Fueling Power Control Switch:Door closed –Door closed –Proximity sensor deactivates DC power to fueling Proximity sensor deactivates DC power to fueling valve switches and panel floodlights. Also valve switches and panel floodlights. Also deactivates AC power to refuel quantity deactivates AC power to refuel quantity indicators.indicators.

Door open –Door open –Proximity sensor allows DC power to fueling Proximity sensor allows DC power to fueling valve switches and panel floodlights. Also allows valve switches and panel floodlights. Also allows AC power to the refuel quantity indicators.AC power to the refuel quantity indicators.



Measurement/Fueling/DefuelingTest Gauges and Fueling Panel:Test Gauges and Fueling Panel:Used by fueling personnel to coordinate the Used by fueling personnel to coordinate the distribution of fuel to the tanks. distribution of fuel to the tanks.

Right-half of pressure fueling stationRight-half of pressure fueling station



Measurement/Fueling/DefuelingFueling Valve Switches:Fueling Valve Switches:OPEN –OPEN –Energizes fueling shutoff valve for respective Energizes fueling shutoff valve for respective tank.tank.

CLOSED –CLOSED –De-energizes fueling shutoff valve for respective De-energizes fueling shutoff valve for respective tank. tank.



Measurement/Fueling/DefuelingFueling VALVE POSITION LIGHTS:Fueling VALVE POSITION LIGHTS:Illuminated –Illuminated –• Respective fueling valve switch in in the OPEN Respective fueling valve switch in in the OPEN

position and the related tank is not full.position and the related tank is not full.

Extinguished –Extinguished –• Respective fueling valve switch in in the OPEN Respective fueling valve switch in in the OPEN

position and the related tank is full.position and the related tank is full.• Respective fueling valve switch is in the Respective fueling valve switch is in the CLOSED CLOSED position.position.



Measurement/Fueling/DefuelingRefuel Quantity Indicators:Refuel Quantity Indicators:Indicates total weight of usable fuel in respective Indicates total weight of usable fuel in respective tank.tank.



Measurement/Fueling/DefuelingTEST GAUGES and FUELING CONTROL Switch:TEST GAUGES and FUELING CONTROL Switch:(spring-loaded to OFF)(spring-loaded to OFF)TEST GAUGES –TEST GAUGES –Checks the operation of the refuel quantity Checks the operation of the refuel quantity indicators by performing a self-test.indicators by performing a self-test.

AUX POWER FUELING CONTROL –AUX POWER FUELING CONTROL –Energizes the fueling system if the fueling power Energizes the fueling system if the fueling power control switch should fail to operate when the control switch should fail to operate when the fueling door is open.fueling door is open.


Measurement/Fueling/DefuelingManual Defueling Valve:Manual Defueling Valve:Open –Open –Connects fuel manifold to pressure fueling station Connects fuel manifold to pressure fueling station for defueling or to transfer fuel from tank to tank. for defueling or to transfer fuel from tank to tank. Transferring of fuel from tank to tank can only be Transferring of fuel from tank to tank can only be performed while the aircraft is on the ground.performed while the aircraft is on the ground.

Closed (picture shows handle in closed position) –Closed (picture shows handle in closed position) –Isolates fuel manifold from pressure fueling Isolates fuel manifold from pressure fueling station.station.

Note: The handle of the defueling valve is such Note: The handle of the defueling valve is such that its access door cannot be closed when the that its access door cannot be closed when the defueling valve is in the open position.defueling valve is in the open position.

This concludes the review of the fueling related panels. The remainderThis concludes the review of the fueling related panels. The remainderof the presentation will discuss more details of the fuel system.of the presentation will discuss more details of the fuel system.

Click Click NextNext to continue. to continue.


Fuel Pump LOW PRESSURE LightsFuel Pump LOW PRESSURE Lights

The fuel pump switches normally The fuel pump switches normally remain in the OFF position until the remain in the OFF position until the pumps are needed.pumps are needed.

With the No. 1 and No. 2 tank fuel pump With the No. 1 and No. 2 tank fuel pump switches in the OFF position, it is switches in the OFF position, it is normal for LOW PRESSURE lights to be normal for LOW PRESSURE lights to be illuminatedilluminated..

With the center tank fuel pump switches With the center tank fuel pump switches in the OFF position, it is normal for in the OFF position, it is normal for LOW PRESSURE lights to be LOW PRESSURE lights to be extinguishedextinguished. The reason for this is . The reason for this is because the center tank is not always because the center tank is not always scheduled to be fueled. Therefore, the scheduled to be fueled. Therefore, the pumps are not utilized and the pump pumps are not utilized and the pump switches are selected OFF. The LOW switches are selected OFF. The LOW PRESSURE lights would be a nuisance PRESSURE lights would be a nuisance to the pilots if they were to remain to the pilots if they were to remain illuminated with the center pump illuminated with the center pump switches in the OFF position. switches in the OFF position.


The following assumes all six fuel The following assumes all six fuel pumps are operating normally and all pumps are operating normally and all three tanks have been fueled:three tanks have been fueled:

When the No. 1 and No. 2 tank pumps When the No. 1 and No. 2 tank pumps are selected ON, the LOW PRESSURE are selected ON, the LOW PRESSURE lights extinguish.lights extinguish.

When the center tank pumps are When the center tank pumps are selected ON, the LOW PRESSURE selected ON, the LOW PRESSURE lights remain extinguished.lights remain extinguished.

Recall that with all six pumps operating, Recall that with all six pumps operating, fuel is delivered to the engines from the fuel is delivered to the engines from the center tank first.center tank first.

Fuel Pump LOW PRESSURE LightsFuel Pump LOW PRESSURE Lights


The following scenarios will The following scenarios will demonstrate the relationship between demonstrate the relationship between the fuel LOW PRESSURE lights and the the fuel LOW PRESSURE lights and the master caution system.master caution system.

Let’s first discuss the LOW PRESSURE Let’s first discuss the LOW PRESSURE lights in the center fuel tank.lights in the center fuel tank.

Fuel Pump LOW PRESSURE LightsFuel Pump LOW PRESSURE LightsWhen their illumination results in a Master CautionWhen their illumination results in a Master Caution


Let’s assume that the center left pump Let’s assume that the center left pump has failed. Because the pump is no has failed. Because the pump is no longer a provider of fuel pressure, the longer a provider of fuel pressure, the respective LOW PRESSURE light respective LOW PRESSURE light illuminates. This illuminates. This does notdoes not result in a result in a MASTER CAUTION because with MASTER CAUTION because with bothboth center pumps ON, center pumps ON, bothboth LOW LOW PRESSURE lights must be illuminated PRESSURE lights must be illuminated in order for the MASTER CAUTION and in order for the MASTER CAUTION and FUEL annunciator lights to FUEL annunciator lights to automatically illuminate. automatically illuminate.

As a result of the center left pump As a result of the center left pump failure, the No. 1 tank pumps will begin failure, the No. 1 tank pumps will begin to feed the No. 1 engine. However, it is to feed the No. 1 engine. However, it is likely that the non-normal procedure likely that the non-normal procedure will suggest opening the crossfeed will suggest opening the crossfeed valve to allow the center right pump to valve to allow the center right pump to deplete center tank fuel. This will also deplete center tank fuel. This will also help to prevent a fuel imbalance help to prevent a fuel imbalance (reference your company operations (reference your company operations manual).manual).


MASTER CAUTION and left MASTER CAUTION and left system annunciator panelsystem annunciator panel


If a pilot were to push either system If a pilot were to push either system annunciator panel, the MASTER annunciator panel, the MASTER CAUTION and FUEL annunciator would CAUTION and FUEL annunciator would illuminate to warn the pilots of the low illuminate to warn the pilots of the low pressure situation in the center left pressure situation in the center left pump.pump.

Note: The system annunciator panels Note: The system annunciator panels are also known as “recall” panels.are also known as “recall” panels.




The master caution system may be The master caution system may be reset by simply depressing either reset by simply depressing either MASTER CAUTION – PUSH TO RESET MASTER CAUTION – PUSH TO RESET light.light.




When the pilot selects the center left When the pilot selects the center left pump switch OFF, the LOW PRESSURE pump switch OFF, the LOW PRESSURE light extinguishes.light extinguishes.




Now, let’s assume that the center right Now, let’s assume that the center right pump has failed. The respective LOW pump has failed. The respective LOW PRESSURE light illuminates. The PRESSURE light illuminates. The MASTER CAUTION and FUEL MASTER CAUTION and FUEL annunciator lights also illuminate. With annunciator lights also illuminate. With one center pump ON and one center one center pump ON and one center pump OFF, the illumination of pump OFF, the illumination of oneone LOW LOW PRESSURE light will automatically PRESSURE light will automatically illuminate the MASTER CAUTION and illuminate the MASTER CAUTION and FUEL annunciator.FUEL annunciator.

In this scenario, fuel is no longer being In this scenario, fuel is no longer being delivered to the engines from the center delivered to the engines from the center tank, and therefore the pumps in the tank, and therefore the pumps in the No. 1 and No. 2 tank will automatically No. 1 and No. 2 tank will automatically begin to feed the engines.begin to feed the engines.




When the pilot selects the center right When the pilot selects the center right pump switch OFF, the LOW PRESSURE pump switch OFF, the LOW PRESSURE light extinguishes.light extinguishes.





This concludes the discussion of the This concludes the discussion of the LOW PRESSURE lights in the center LOW PRESSURE lights in the center tank. The LOW PRESSURE lights in the tank. The LOW PRESSURE lights in the No. 1 tank will be discussed next.No. 1 tank will be discussed next.




Let’s assume that the AFT pump in the Let’s assume that the AFT pump in the No. 1 tank has failed. Because the No. 1 tank has failed. Because the pump is no longer a provider of fuel pump is no longer a provider of fuel pressure, the respective LOW pressure, the respective LOW PRESSURE light illuminates. This PRESSURE light illuminates. This does does notnot result in a MASTER CAUTION result in a MASTER CAUTION because because bothboth LOW PRESSURE lights in LOW PRESSURE lights in the No. 1 fuel tank must be illuminated the No. 1 fuel tank must be illuminated in order for the MASTER CAUTION and in order for the MASTER CAUTION and FUEL annunciator lights to FUEL annunciator lights to automatically illuminate.automatically illuminate.




If a pilot were to push either system If a pilot were to push either system annunciator panel, the MASTER annunciator panel, the MASTER CAUTION and FUEL annunciator would CAUTION and FUEL annunciator would illuminate to warn the pilots of the low illuminate to warn the pilots of the low pressure situation in the No. 1 tank AFT pressure situation in the No. 1 tank AFT pump.pump.




When the pilot selects the No. 1 tank When the pilot selects the No. 1 tank AFT pump switch OFF, the LOW AFT pump switch OFF, the LOW PRESSURE light remains illuminated.PRESSURE light remains illuminated.




Now, let’s assume that the FWD pump Now, let’s assume that the FWD pump in the No. 1 tank has failed. The in the No. 1 tank has failed. The respective LOW PRESSURE light respective LOW PRESSURE light illuminates. The MASTER CAUTION illuminates. The MASTER CAUTION and FUEL annunciator lights also and FUEL annunciator lights also illuminate because illuminate because bothboth LOW LOW PRESSURE lights in the No. 1 fuel tank PRESSURE lights in the No. 1 fuel tank are illuminated.are illuminated.

The No. 1 engine would continue to run The No. 1 engine would continue to run because the engine driven fuel pump is because the engine driven fuel pump is drawing fuel out of the No. 1 tank via drawing fuel out of the No. 1 tank via the bypass valve.the bypass valve.




When the pilot selects the No. 1 tank When the pilot selects the No. 1 tank FWD pump switch OFF, the LOW FWD pump switch OFF, the LOW PRESSURE light remains illuminated.PRESSURE light remains illuminated.






This concludes the discussion of the This concludes the discussion of the LOW PRESSURE lights in the No. 1 LOW PRESSURE lights in the No. 1 tank. The LOW PRESSURE lights in the tank. The LOW PRESSURE lights in the No. 2 tank will be discussed next. You No. 2 tank will be discussed next. You will discover that the No. 1 and No. 2 will discover that the No. 1 and No. 2 tank LOW PRESSURE lights function tank LOW PRESSURE lights function exactly the same.exactly the same.



Let’s assume that the AFT pump in the Let’s assume that the AFT pump in the No. 2 tank has failed. Because the No. 2 tank has failed. Because the pump is no longer a provider of fuel pump is no longer a provider of fuel pressure, the respective LOW pressure, the respective LOW PRESSURE light illuminates. This PRESSURE light illuminates. This does does notnot result in a MASTER CAUTION result in a MASTER CAUTION because because bothboth LOW PRESSURE lights in LOW PRESSURE lights in the No. 2 fuel tank must be illuminated the No. 2 fuel tank must be illuminated in order for the MASTER CAUTION and in order for the MASTER CAUTION and FUEL annunciator lights to FUEL annunciator lights to automatically illuminate.automatically illuminate.




If a pilot were to push either system If a pilot were to push either system annunciator panel, the MASTER annunciator panel, the MASTER CAUTION and FUEL annunciator would CAUTION and FUEL annunciator would illuminate to warn the pilots of the low illuminate to warn the pilots of the low pressure situation in the No. 2 tank AFT pressure situation in the No. 2 tank AFT pump.pump.




When the pilot selects the No. 2 tank When the pilot selects the No. 2 tank AFT pump switch OFF, the LOW AFT pump switch OFF, the LOW PRESSURE light remains illuminated.PRESSURE light remains illuminated.




Now, let’s assume that the FWD pump Now, let’s assume that the FWD pump in the No. 2 tank has failed. The in the No. 2 tank has failed. The respective LOW PRESSURE light respective LOW PRESSURE light illuminates. The MASTER CAUTION illuminates. The MASTER CAUTION and FUEL annunciator lights also and FUEL annunciator lights also illuminate because illuminate because bothboth LOW LOW PRESSURE lights in the No. 2 fuel tank PRESSURE lights in the No. 2 fuel tank are illuminated.are illuminated.

The No. 2 engine would continue to run The No. 2 engine would continue to run because the engine driven fuel pump is because the engine driven fuel pump is drawing fuel out of the No. 2 tank via drawing fuel out of the No. 2 tank via the bypass valve.the bypass valve.




When the pilot selects the No. 2 tank When the pilot selects the No. 2 tank FWD pump switch OFF, the LOW FWD pump switch OFF, the LOW PRESSURE light remains illuminated.PRESSURE light remains illuminated.






This concludes the discussion of the This concludes the discussion of the LOW PRESSURE lights in the No. 2 LOW PRESSURE lights in the No. 2 tank. tank.



Fuel Pump Power SourcesFuel Pump Power Sources

MAIN BUS 1MAIN BUS 1

TRANSFER BUS 1TRANSFER BUS 1 TRANSFER BUS 2TRANSFER BUS 2

MAIN BUS 2MAIN BUS 2MAIN BUS 1MAIN BUS 1

MAIN BUS 2MAIN BUS 2


Fuel Tank Capacities Fuel Tank Capacities

No. 1 tankNo. 1 tank No. 2 tankNo. 2 tankCenter Center

tanktank

1,499 U.S. gallons1,499 U.S. gallons

10,118 pounds*10,118 pounds*4,650 KG4,650 KG

*Fuel density assumed to be 6.75lbs/gallon*Fuel density assumed to be 6.75lbs/gallon

1,499 U.S. gallons1,499 U.S. gallons

10,118 pounds*10,118 pounds*4,650 KG4,650 KG

2,313 U.S. 2,313 U.S. gallonsgallons

15,613 15,613 pounds*pounds*7.176 KG7.176 KG

These figures represent the approximate amount of useable fuel. Weight and These figures represent the approximate amount of useable fuel. Weight and balance calculations and the appropriate loading manual will give exact figures for balance calculations and the appropriate loading manual will give exact figures for

your specific aircraft and condition.your specific aircraft and condition.

b737-300/400 fuel

Engineering