17.b737 Ng Ch 28 (2)

B737 NG Difference

CHAPTER 28 Fuel System

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B737 NG Difference FUEL SYSTEM -- INTRODUCTION Purpose The fuel system has these primary functions: - Holds fuel for use by engines and APU - Gives fuel to the engines - Gives fuel to the APU. General The fuel system has these subsystems: - Fuel storage - Pressure refueling - Engine fuel feed - APU fuel feed - Defuel - Transfer - Fuel quantity indicating system - Fuel temperature indication.

FTG - forward tank group kg - kilograms lb - pounds PS - pressure switch TP - test port TRV - tank relief valve V - valve

Abbreviations and Acronyms ATG - aft tank group CV - check valve CDS - common display system DV - drain valve F - filter FS - float switch FA - flame arrestor FQPU - fuel quantity processor unit FQIS - fuel quantity indicating system

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B737 NG Difference FUEL SYSTEM -- GENERAL DESCRIPTION Defuel System Use the defuel system to remove fuel from each tank.

This system can be used to transfer fuel between tanks on the ground. Fuel Quantity Indicating System The fuel quantity indicating system (FQIS) shows the fuel weight of the main tanks and the center tank on the common display system (CDS) primary engine display and the P15 refueling panel. Total fuel weight shows in the flight management computer system (FMCS) data on the CDU. Fuel Temperature Indicating System Main tank 1 fuel temperature shows on the fuel system panel (P5).

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B737 NG Difference FUEL STORAGE -- GENERAL DESCRIPTION Fuel Tank Configuration These are the fuel tanks: - Main tank 1 - Main tank 2 - Center tank. Surge tanks collect fuel overflow only. The fuel overflow in the left wing surge tank drains to main tank 1. The fuel overflow in the right wing surge tank drains to main tank 2. If the fuel level is high enough in the surge tank, fuel drains out of the vent scoop. Component Location Main tank 1 is in the wing box of the left wing. Main tank 2 is in the wing box of the right wing. The center tank is in the fuselage, and the left and right wing inboard sections. Capacity The capacity of main tank 1 is 8630 lb (3915 kg). The capacity of main tank 2 is 8630 lb (3915 kg). The capacity of the center tank is 28,830 lb (13,066 kg). Fuel tank capacity does not include surge tanks. The capacity of each surge tank is 235 lb (107 kg).

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B737 NG Difference FUEL STORAGE -- FUEL TANK ACCESS General Wing fuel tank access panels allow entrance into each fuel and surge tank. The wing fuel tank and center tank access panels are on the bottom wing skin. One center tank access panel allows entrance into the center tank through the fuselage. This panel is in the left air conditioning compartment.

Fuel Tank Access Panels The fuel tank access panels attach to the bottom wing skin with a clamp ring. An aluminum gasket makes a correct fit and an electrostatic bond. Impact resistant fuel tank access panels are in areas that can receive impact damage. The three inboard fuel tank access panels on each wing are impact resistant panels.

Wing ribs divide the fuel tanks into bays. Wing fuel tank access panels are between the wing ribs. Access across wing ribs to adjacent bays is through cutouts. Wing rib 8 in main tank 1 and main tank 2 has baffle check valves. The check valves let fuel flow inboard but do not let fuel flow outboard. Tank end ribs close the ends of each fuel tank. There is no fuel flow through the tank end ribs. Fuel Tank Locations The side of body rib is rib 1. Main tank 1 is between rib 5 and rib 22. The location of main tank 2 is the same. The center tank is between rib 5 in the left wing and rib 5 in the right wing. The surge tank for main tank 1 and main tank 2 is between rib 22 and rib 25.

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B737 NG Difference FUEL STORAGE -- SUMP DRAIN VALVES General The sump drain valves let these drain from each fuel tank:

The sump drain valve for the surge tanks is outboard of rib 22. The sump drain valve is on the bottom of the wing.

- Fuel

Operation

- Water

The procedure to drain fluid from these tanks is the same:

- Main tank 1

- Contamination. Sump drain valves are at the low point of each tank.

- Main tank 2

The sump drain valves in these tanks attach to the bottom wing skin:

- Surge tank.

- Main tank 1

To drain fluid from the center tank, open the access door and pull down on the rod. An internal spring closes the sump drain valve.

- Main tank 2 - Surge tank. The sump drain valve in the center tank attaches to the lower wing center section. Component Location

The sump drain valve for main tank 1 and main tank 2 is outboard of rib five. The sump drain valves are on the bottom of the wing. The sump drain valve for the center tank is near the center of the tank. Access the sump drain valve from an access door on the lower fuselage skin. The access door is between the two air conditioning access doors.

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To open the sump drain valve, push up on the center of the valve. An internal spring closes the sump drain valve.

Training Information Point Replace the primary seal of a main tank sump drain valve by removing the valve core plug and valve poppet. Defueling the main tank is not necessary. However, the tank must be defueled if the whole main tank drain valve must be replaced. The center tank sump drain assembly can be replaced without defueling the center tank.

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B737 NG Difference FUEL STORAGE -- FUEL VENT SYSTEM General

The vent scoop and pressure relief valve are on an access panel in each surge tank.

The fuel vent system keeps the pressure of the fuel tanks near the ambient pressure. Too large a pressure difference can cause damage to the wing structure.

The nitrogen generation system supply components are in the center tank.

Drains let fuel in the vent system go back to the tanks. Flame arrestors make sure too much heat does not go in the fuel vent system. A clogged flame arrestor causes the pressure relief valve in the surge tank to open. When the pressure relief valve opens, it also becomes a vent for the fuel vent system.

A vent/transfer line connects each auxiliary tank group to the center tank. Component Locations Stringers and the upper wing skin make the vent channels. The vent channels have drain float valves in the center tank. Vent tubes attach to vent channels. Each vent tube has a drain float valve. A fuel vent float valve is on the outboard fuel tank end rib in main tank 1 and main tank 2. A surge tank drain check valve is on the outboard fuel tank end rib in main tank 1 and main tank 2.

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Functional Description During refuel, the displaced air and fuel vapor in the tanks goes out. Vent channels and vent tubes cause a pressure equalization between each tank and the surge tanks when the airplane is in a climb attitude. The surge tanks are open to the atmosphere through the vent scoop. The fuel vent float valves cause a pressure equalization between main tank 1, main tank 2, and the surge tanks when the airplane is in a cruise or descent attitude. The drain float valves in the vent tubes and the vent channels let fuel in the vent system drain into the tank when the fuel level is lower than the valve. The surge tank drain check valve lets fuel in the surge tank flow to main tank 1 or main tank 2. The surge tank drain check valve also prevents fuel flow from main tank 1 and main tank 2 to the surge tank. The pressure relief valve prevents damage to the wing structure when there is too much positive or negative pressure difference between the tanks and the ambient

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B737 NG Difference FUEL STORAGE -- FUEL VENT SYSTEM air. The pressure relief valve is normally closed. When the valve is closed, it is smooth with the bottom surface of the wing. When there is too much positive or negative pressure difference, the pressure relief valve opens, and part of the valve is in the fuel tank. After the valve opens, it stays in the open position. In the open position, the valve also is a vent in the surge tank. You pull the reset handle to move the pressure relief valve to the closed position. For normal operations, you must make sure the pressure relief valve is closed. An open pressure relief valve is a symptom of a problem in the fuel vent system.

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B737 NG Difference FUEL STORAGE -- FUEL TANK SCAVENGE SYSTEM General

Training Information Point

The main tank water scavenge system removes water/fuel from the low points of each tank to prevent corrosion.

The four water scavenge ejector pump nozzles are colored red, the fuel scavenge ejector pump is colored gold.

The scavenged water/fuel is sent to the boost pump inlets.

The center tank fuel scavenge system increases the quantity of usable fuel. Functional Description The center tank, main tank 1, and main tank 2 boost pumps control the operation of the water scavenge ejector pumps. There is one water scavenge ejector pump in the main tank 1 and main tank 2. There are two water scavenge ejector pumps in the center tank. All of the water scavenge ejector pumps are on the rear spar accessible from the main wheel well. The boost pumps supply motive flow to the jet pumps. The jet pumps have no moving parts. The left forward boost pump supplies motive flow to a jet pump. The jet pump removes fuel from the center tank and moves it to main tank 1. It is on the left front spar. A fuel scavenge shutoff valve controls fuel flow to main tank 1. When the fuel level in main tank 1 decreases to 4487 lb (1990 kg) the float valve opens.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- INTRODUCTION General The pressure refueling system allows the refueling of all tanks. The system is also used for fuel transfer from tank to tank and for defuel.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- GENERAL DESCRIPTION General

- External power connected to the airplane but not

All tanks fill from the refueling station at the right wing. The refueling station has these components:

on electrical system buses

- Refueling panel

- Battery power - the battery switch must be on.

- Refueling manifold - Refueling receptacle - Refueling shutoff valves (3). Control The refueling station permits automatic and manual control of the refueling shutoff valves. The refueling station receives 28v dc hot battery bus power through the refueling power control relay. The relay energizes when you open the door of the refueling station. Power for the relay comes from one of these sources: - Switched hot battery bus - DC bus 1 - Bus power control unit (BPCU) internal transformer rectifier. Use the refueling indication test switch to connect an alternative ground for the refueling power control relay. You can refuel the airplane with one of these electrical power sources: - External power on electrical system buses Manual No : JCT – 0151

- APU generator The solenoid for a refueling shutoff valve energizes when the control switch is moved to the OPEN position. The valve opens if fuel pressure is available. A float switch removes power to the refueling shutoff valve when the tank is full. Power is removed when the control switch is moved to the CLOSE position. Without electrical power, the valve closes. Use the preselect switch of the indicator to select the total quantity of fuel to put into the tank. The solenoid for a refueling shutoff valve energizes when the control switch is moved to the OPEN position. The valve opens if fuel pressure is available. The indicator removes power to the refueling shutoff valve when the fuel gets to the selected quantity. Power is removed when the control switch is moved to the CLOSE position. Without electrical power, the valve closes. There is a manual override plunger on each refueling shutoff valve. The plunger and fuel pressure let you open the valve if the solenoid has a failure or electrical power is not available. Indication

Three valve position lights show that there is power to the refueling shutoff valves. The light does not show that the valve is open. These lights are press-to-test.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- GENERAL DESCRIPTION Three fuel quantity indicators show fuel quantity in each tank. Main Tank and Center Tank Refueling Control Use the preselect switch on the indicator to set the quantity of fuel to put into the tanks. The main tanks and center tanks get fuel through the refueling shutoff valves. Each valve has a solenoid that energizes when the refueling control switch is moved to the OPEN position. The valve opens if refueling pressure is available at the fueling station. Fuel then goes to the tanks. Each refueling shutoff valve closes when its solenoid deenergizes. The solenoid de-energizes when the tank is full and the float switch opens. It also deenergizes when the quantity of fuel in the tank is equal to the preselected value. Then the indicator removes power. Power is removed when the control switch is moved to the CLOSE position. Refueling Fuel Flow When the refueling valves are open, fuel flows to the tanks. Fuel flow to tank 2 is through a diffuser. The diffuser makes sure that tank 2 refuels at the same rate as tank 1.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- COMPONENT LOCATION General These pressure refueling system components are at the refueling station: - Refueling receptacle - Refueling manifold body - Refueling check valve - Refueling body/elbow assembly - Refueling shutoff valve - Refueling power control switch A refueling float switch is in each tank.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- P15 REFUELING PANEL General

Refueling Valve Control Switches

The P15 refueling panel has these components:

The refueling valve control switches are two-position switches. The refueling valve solenoid energizes when the switch is moved to OPEN, and power is available.

- Refueling valve open lights - Refueling indication test switch - Fuel quantity indicators

The valve opens if fuel pressure is available at the refueling manifold. In the CLOSED position, the refueling valve solenoid de-energizes and the valve closes.

- Refueling power control switch.

Fuel Indicators

Refueling Valve Open Lights

The indicators are amber LED displays. The indicators use 28v dc to operate.

- Refueling valve control switch

During refueling of the main tanks and center tanks, the blue valve position lights come on when the refueling shutoff valve solenoids have power. Refueling Indication Test Switch The refueling indication test switch is a three position switch. The FUEL DOOR SWITCH BYPASS position and the TEST GAUGES position are momentary positions. The switch is spring-loaded to the center (neutral) position. When the switch is in the FUEL DOOR SWITCH BYPASS position, the power control relay gets a ground. The normal ground for this relay is through the refueling power control switch. This relay controls power for refueling. When the switch is in the TEST GAUGES position, the fuel indicators do a display test. Fuel quantity in the flight compartment does not change during this test. Manual No : JCT – 0151

The fuel indicators show fuel quantity in a digital format. Fuel quantity shows in pounds or kilograms. On fuel indicators with preselect. The preselect switch lets you set a total fuel tank quantity at which refuel stops. When the fuel quantity in the fuel tank is equal to the preselect quantity, the refueling valves close. The indicators have a tank overfill indication. The fuel quantity indication flashes on and off at a one second interval if the quantity is more than the rated capacity of that tank. The flight compartment fuel quantity indication does not flash. Refueling Power Control Switch The refueling power control switch closes to connect an electrical ground for the R11 fueling power control

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B737 NG Difference PRESSURE REFUELING SYSTEM -- P15 REFUELING PANEL relay. The control switch closes when the refueling station door opens, and the magnet is near the switch. The switch opens when the door closes, and the magnet moves away from the switch. Training Information Point If the refueling station door is open, and the refueling station does not have power, move the refueling indication test switch to the FUEL DOOR SWITCH BYPASS position. This supplies hot battery bus power to the refueling station.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- REFUELING FLOAT SWITCHES General The refueling float switches prevent over-fueling the fuel tanks. The refueling float switches remove power to the refueling valves when the fuel level in the tank is full. The refueling float switches have a float that is in a cylindrical container. When the tank is less than full, the float switch lets power go to the refueling valve solenoid. When the tank is full, the refueling float switch removes power to the refueling valve solenoid. Training Information Point The conduit contains a polymer protective liner material to eliminate wire damage from chafing. The liner for the main tank float switch conduit comes installed with the conduit. The float switch and the conduit are a single LRU and must be removed and installed together. For the center tank float switch, the float switch can be replaced separately from the conduit. A new liner has to be installed whenever the conduit or the float switch is replaced.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- FUNCTIONAL DESCRIPTION - POWER AND CONTROL General

Refueling Valve Closed Control

Power for the pressure refueling system comes from the 28v dc hot battery bus. When the refueling station gets power, the outboard refueling panel flood light and the outboard refueling nozzle flood light come on. The refueling indicators also get power.

The refueling valves close when one of these conditions are true:

Hot Battery Bus

- Quantity of fuel in the fuel tank is equal to the preselect fuel quantity (w/preselect)

When the refueling panel door opens, the refueling power control relay energizes. This sends hot battery bus power to the refueling panel.

- Refueling panel does not have power - Refueling valve control switch is in the CLOSED position

- Refueling float switch is in the full position - No fuel pressure is at the refueling valve.

Refueling Valve Open Control

Refueling Valve Open Light - Off

The refueling valves open when all of these conditions are true:

The refueling valve open light goes off when there is no power to the refueling valve solenoid.

- There is power to the refueling panel

Fuel Indication Test Switch

- Refueling valve control switch is in the OPEN

When the switch is in the FUEL DOOR SW BYPASS position, the refueling panel gets 28v dc hot battery bus power.

position

Put the switch in the TEST GAUGES position to do a test of the fuel indicators.

- Refueling float switch is in the not full position - Refueling valve solenoid is energized

Nitrogen Generation System

- Fuel pressure is at the refueling valve.

Refueling Valve Open Light - On The refueling valve open light comes on when there is power to the refueling valve solenoid. The light does not show that the refueling valve is open. The solenoid must have power, and the valve must have fuel pressure to open. Manual No : JCT – 0151

When the center tank refueling valve solenoid is powered, the center tank refuel valve relay R951 is energized. This prevents operation of the nitrogen generation system during refueling of the center tank.

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B737 NG Difference PRESSURE REFUELING SYSTEM -- OPERATION General Fueling placards on the refueling station door have instructions for refueling. Use the information on these placards when you refuel the aircraft. The refueling station receives power when you open the refueling station door. Training Information Point CAUTION: DO NOT USE WIDE CUT FUEL WHEN IT IS NOT PERMITTED. A FLAMEOUT CAN OCCUR AND ENGINE POWER CAN DECREASE SUDDENLY. Wide cut fuel is not certified for use on the Boeing 737600/700/800/900/BBJ model of the airplane. Wide cut fuel is fuel that satisfies ASTM D1655, Jet B or MIL-T- 5624, JP-4. Wide cut fuel contains kerosene and naphtha (gasoline) fractions.

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B737 NG Difference DEFUEL -- INTRODUCTION General The defuel system removes fuel from the fuel tanks to the refuel station. The defuel system also permits fuel transfer from one fuel tank to another.

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B737 NG Difference DEFUEL AND TRANSFER -- GENERAL DESCRIPTION General The defuel system permits pressure defuel of each tank and suction defuel of main tank 1 and main tank 2. The defuel system also allows fuel transfer on the ground between tanks. Pressure Defuel Use these to do a pressure defuel of the tanks: - Refueling station - Fuel pumps - Defueling valve - Crossfeed valve. Suction Defuel Use these to suction defuel the main tanks: - Refueling station - Defueling valve - Crossfeed valve. Fuel Transfer Use these to do a fuel transfer between tanks: - Refueling station - Fuel pumps - Crossfeed valve. Manual No : JCT – 0151

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B737 NG Difference DEFUEL -- COMPONENT LOCATION Location The defueling valve is on the right wing front spar. The valve connects between the right engine fuel feed manifold and the refueling station tubing.

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B737 NG Difference DEFUEL -- DEFUELING VALVE Purpose The defueling valve connects the right engine fuel feed manifold with the defuel manifold. This permits removal of fuel from the fuel tanks. Description The defueling valve operates manually. It has these components: - Handle

- Valve assembly. Handle The handle operates the defueling valve. The handle is also a position indicator. The defueling valve access door cannot close with the handle in the open position. Valve Assembly The valve assembly attaches to structure in the fuel tank. The valve assembly connects to the defuel manifold and the right engine fuel feed manifold.

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B737 NG Difference DEFUEL AND TRANSFER -- OPERATION General

- Move the handle on the defueling valve to the open position

There are two ways to do a defuel of the fuel tanks, pressure defuel and suction defuel. Each tank can be pressure defueled. Only main tank 1 and main tank 2 can be suction defueled. Fuel can be moved between each of the tanks.

- Open the crossfeed valve if necessary

Suction defuel can only be done on main tank 1 if you do a suction defuel of main tank 2 at the same time. When either main tank is empty, air goes into the manifold, and fuel flow stops.

- Start the suction with the ground source - When the fuel tank is empty, move the handle on the defueling valve to the closed position - Disconnect the refueling nozzle. Fuel Transfer

This is a summary of the pressure defuel procedure:

To move fuel between tanks, use the defuel system, the refuel system, and the engine fuel feed system. This is a summary of the fuel transfer procedure:

- Connect the refueling nozzle

- Move the defueling valve to the open position

- Move the handle on the defueling valve to the open position

- Put on the boost pumps in the tank to remove fuel from

- Put the boost pumps on to the related tank

- Open the crossfeed valve

- Open the crossfeed valve if necessary

- Move the refueling valve switch to the open position for the tank to put fuel in

Pressure Defuel

- Put the boost pumps off when the tank is empty - Move the handle on the defueling valve to the closed position - Disconnect the refueling nozzle.

- After fuel transfer, put the boost pumps off - Close the crossfeed valve - Move the defueling valve to the closed position.

Suction Defuel This is a summary of the suction defuel procedure: - Connect the refueling nozzle

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- INTRODUCTION General The engine fuel feed system supplies fuel to the engines from main tank 1, main tank 2, and the center tank. Operate the engine fuel feed system from the fuel system panel on P5, the engine start levers on the control stand and the fire handles on the P8 panel. The fuel test panel on P61 does a check of the auto shutoff function of the center wing boost pumps.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- GENERAL DESCRIPTION General

Center Tank Boost Pump Indication

The engine fuel feed system controls and supplies fuel to the engines. It uses these inputs:

- Fuel control panel

A LOW PRESSURE light comes on when the center tank boost pump pressure is low and the center tank boost pump switch is in the ON position.

- Engine start switches

Main Tank Fuel Boost Pump

- Engine fire switches

A switch on the fuel system panel controls each forward and aft boost pump for main tank 1 and main tank 2. The switches control power to the pumps.

- Fuel test panel. The engine fuel feed system uses these components to supply fuel to the engines:

Main Tank Fuel Boost Pump Indication

- Forward boost pumps

A LOW PRESSURE light comes on when the fuel boost pump pressure is low, or the boost pump switch is in the OFF position.

- Aft boost pumps

Bypass Valve

- Bypass valve - Crossfeed valve

A bypass valve gives a secondary fuel flow path to the engines. The bypass valves operate automatically.

- Engine fuel spar valve.

Engine Fuel Spar Valve

Center Tank Boost Pump Control

The engine fuel spar valves control fuel flow to the engines. The engine start levers and the engine fire switches control the engine fuel spar valves.

- Center tank boost pumps

A switch on the fuel system panel controls each center tank boost pump. The switches control electrical power to the pumps. The center tank boost pumps have an auto shutoff relay that can de-energize the boost pump relay. This removes power to the boost pumps and prevents overheat damage. The auto shutoff relay energizes after a time delay of 15 seconds when there is low boost pump pressure. Do a test of the auto shutoff function from the fuel test panel on P61. Manual No : JCT – 0151

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- GENERAL DESCRIPTION Emergency Fuel Shutoff Battery

The emergency fuel shutoff battery makes sure that the engine fuel feed system always has power to close the engine fuel spar valve. Engine Fuel SPAR Valve Indication A blue SPAR VALVE CLOSED light shows valve position. Crossfeed Valve The crossfeed valve lets one fuel tank supply fuel to the two engines. A switch on the fuel system panel controls the crossfeed valve. Crossfeed Valve Indication A blue VALVE OPEN light shows valve position.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- COMPONENT LOCATION General

Engine Fuel Spar Valves

The engine fuel feed system has these components:

There is one engine fuel spar valve for each engine. The engine fuel spar valves are on the front spar outboard of each engine strut.

- Center tank boost pump (2) - Forward and aft boost pump (4)

Bypass Valves

- Crossfeed valve - Engine fuel spar valve (2)

There is one bypass valve in main tank 1 and main tank 2. The bypass valve connects to the fuel feed manifold.

- Bypass valve (2)

Water Scavenge Ejector Pumps

- Water scavenge ejector pump (4).

Each main tank has a water scavenge ejector. There are two water scavenge ejector pumps in the center tank. All of the water scavenge ejector pumps are on the rear spar.

Center Tank Boost Pumps There are two center tank boost pumps in the center tank. They are on the rear spar. Access to the center tank boost pumps is through the wheel wells.

Emergency Fuel Shutoff Battery The emergency fuel shutoff battery is in the P6 panel.

Forward And Aft Boost Pumps Each main tank has a forward and aft boost pump. The forward boost pumps are on the front spar. The aft boost pumps are on the rear spar. Access to the forward boost pumps is through extended krueger flaps. Access to the aft boost pumps is through the wheel wells. Crossfeed Valve The crossfeed valve is on the right side of the center tank on the rear spar. Access to the crossfeed valve is through the right wheel well.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- CENTER TANK BOOST PUMP General The center tank boost pumps supply fuel from the center tank to the engine fuel feed manifold. The center tank boost pump supplies fuel at a minimum pressure of 23 psi and a minimum flow rate of 20,000 pph (9,071 kgph). Each pump assembly has a motor and a housing.

The removal check valve is a poppet type valve. The removal check valve closes when you remove the motor. This allows motor removal without defueling the center tank.

The vapor discharge check valve prevents a reverse flow of fuel from the tank, back through the pump. Center Tank Boost Pump Motor The motor has the impeller and uses 3-phase, 115v ac power. It is inside the housing.

Location

The center tank boost pumps are on the rear spar in the wheel well. The pressure switch for the right and left center tank pump is on the rear spar. Access to the left center tank boost pump pressure switch is through the left wheel well. Access to the right center tank boost pump pressure switch is through the right wheel well. Center Tank Boost Pump Housing

Pressure Switch The low pressure switch sends a low center tank boost pump pressure signal to the LOW PRESSURE light (P5). Bypass Valve There is one bypass valve in main tank No. 1 and No. 2. The bypass valve connects to the fuel feed manifold. A bypass valve supplies a secondary fuel flow path to the engines. The bypass valves operate automatically.

The housing contains these components: - Discharge check valve - Removal check valve

- Vapor discharge check valve. The discharge check valve is a flapper type valve. The discharge check valve prevents fuel flow from the engine feed manifold through the pump. Manual No : JCT – 0151

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- CENTER TANK BOOST PUMP - FUNCTIONAL DESCRIPTION Left Center Tank Boost Pump Control

Left Center Tank Boost Pump Auto Shutoff

The center tank left boost pump switch controls the center tank left boost pump relay (R54) and the secondary boost pump center tank left relay (R962). The series connected relays R54 and R962 control electrical power to the left center tank boost pump.

The left center tank boost pump has an automatic shutoff function.

When the switch is in the on position, 115v ac goes to the relays R54 and R962. When the relays energize, power goes from the 115v ac transfer bus to the left center tank boost pump. When the switch is in the off position, the relays do not get 115v ac. When the relays are not energized, the center tank boost pump does not get power. Pressure Indication A lOW PRESSURE light comes on when both these conditions are true: - The center tank left boost pump switch is in the ON position - Left center tank boost pump pressure is 18 psig or less. A master caution indication comes on if either center tank boost pump LOW PRESSURE light comes on.

The automatic shutoff function de-energizes the left center tank boost pump relay (R54) and the secondary boost pump center tank left relay (R962) after a time delay of 15 seconds when there is low pressure. When one or both relays are not energized, the center tank boost pump does not get power. FUEL TEST PANEL The fuel test panel has a three position switch. A switch guard keeps the switch in the neutral position. This switch is used to test the operation of the automatic shutoff circuit. When the switch is moved to the AUTO SHUT OFF position the time delay circuit prevents electrical current flow for 15 seconds. After 15 seconds the left auto shutoff time delay relay (R934) operates and its internal contacts open. This removes power to operate the center tank left boost pump. A low pressure condition causes the center tank left boost pump low press switch to close. The LOW PRESSURE, MASTER CAUTION, and FUEL annunciator lights come on. Ground Fault Protection

The boost pump relay has ground fault interrupter (GFI) control logic. The GFI senses the current to the relay.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- CENTER TANK BOOST PUMP - FUNCTIONAL DESCRIPTION If the current to the relay is excessive or a phase anomaly, the logic will de-energize the relay. The GFI can be reset by a button on the relay located in the P91. Training Information Point A periodic check on the condition of the pump relay contacts is performed. This is to check for welded contacts or a relay that remains closed when the relay is de-energized. This page shows control of the left center tank boost pump. Control of the right center tank boost pump is almost the same.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- MAIN TANK 1 FORWARD AND AFT BOOST PUMPS General

- Vapor discharge check valve.

The boost pumps supply fuel from main tank 1 to the engine feed manifold. The boost pumps supply fuel at a minimum pressure of 10 psi at a flow rate of 20,000 pph (9,071 kgph). Each of the boost pumps in main tank 1 and main tank 2 are interchangeable. The main tank boost pumps are not interchangeable with the center tank boost pumps. Location

The discharge check valve is a flapper type valve. The discharge check valve prevents fuel flow from the engine feed manifold through the pump. The removal check valve is a poppet type valve. The removal check valve closes when you remove the motor. This permits motor removal without defueling tank 1. The vapor discharge check valve prevents a reverse flow of fuel, from the tank, through the pump.

The forward boost pump is on the left wing front spar. Access to the left forward boost pump is through a deployed leading edge flap. The aft boost pump is on the left wing rear spar. Access to the aft boost pump is through the left wheel well.

Boost Pump Motor

The pressure switch for the forward boost pump is on the front spar. Access to this pressure switch is through an access panel on the top of the left wing. The pressure switch for the aft boost pump is on the rear spar. Access to this pressure switch is through the left wheel well.

The low pressure switch sends a low boost pump pressure signal to the LOW PRESSURE light (P5).

The motor has the impeller and uses three-phase, 115v ac power. It is inside the housing. Pressure Switch

Boost Pump Housing The housing contains these components: - Discharge check valve - Removal check valve

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- FORWARD AND AFT BOOST PUMP - FUNCTIONAL DESCRIPTION General This page shows control of the left forward boost pump. Control of the left aft, right forward, and right aft boost pump is the same.

during recall or when both main tank 1 boost pump pressures are low.

Left Forward Boost Pump Control The forward boost pump switch for main tank 1 controls the main tank 1 forward boost pump relay. This boost pump relay controls power to the left forward boost pump. When the switch is in the ON position, 115v ac goes to the relay. When the relay energizes, power goes from the 115v ac transfer bus to the left forward boost pump. When the switch is in the OFF position, the relay does not get 115v ac. When the relay is not energized, the left forward boost pump does not receive power. The boost pump relays have a ground fault interrupter (GFI) control logic. The GFI senses the current to the relay. If the current to the relay is excessive, the logic will de-energize the relay. The GFI is reset by a button on the relay. Pressure Indication A lOW PRESSURE light comes on when the forward boost pump pressure for the main tank 1 is 4 psig or less. The MASTER CAUTION and the FUEL annunciator lights come on

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- WATER SCAVENGE EJECTOR PUMP General The water scavenge ejector pumps remove water from the low points in each tank to prevent corrosion. Location The water scavenge ejector pumps are on the rear spar. There is one water scavenge ejector pump in main tank 1 and one water scavenge ejector pump in main tank 2. Access to the water scavenge ejector pump for main tank 1 is through an access panel on the bottom of the left wing. Access to the water scavenge ejector pump in main tank 2 is through an access panel on the bottom of the right wing. There are two water scavenge ejector pumps in the center tank. Access to the water scavenge ejector pump in the left side of the center tank is through the left wheel well. Access to the water scavenge pump in the right side of the center tank is through the right wheel well. Functional Description The water scavenge ejector pumps operate when the boost pumps are on. The water scavenge ejector pump uses fuel flow from the boost pumps as motive flow. The motive flow through the water scavenge ejector pump causes a suction. This suction takes water and fuel from the low points in each tank. The water and fuel that comes out of the water scavenge ejector pump goes to the boost pump inlets.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- FUEL CROSSFEED VALVE General The crossfeed valve lets fuel flow between the left and right engine fuel feed manifolds. With the connection of the two engine fuel feed manifolds, one fuel tank supplies fuel to both engines.

The mount plate attaches to the rear spar. The actuator adapter plate attaches to the mount plate with adjustment screws. Loosen the adjustment screws to rotate the actuator adapter plate. Turn the actuator adapter plate to align the butterfly valve with the actuator.

Location

Actuator

The fuel crossfeed valve is on the right wing rear spar. Access is through the right wheel well.

The actuator is a 28v dc motor. It has a manual override lever that permits valve operation without electrical power. The lever aligns with valve position indicators on the adapter. This shows valve position.

Motor Actuated Valve The motor actuated valve has these parts:

The fuel crossfeed valve actuator is interchangeable with the engine fuel spar valve actuator.

- Valve body - Adapter and shaft - Actuator. Valve Body The valve body connects to the left and right engine fuel feed manifold. The valve body has an operating shaft and a butterfly valve (not shown). There are no hard stops for the butterfly valve. The alignment marks show valve position. Adapter and Shaft

The adapter and shaft attaches between the rear spar and the operating shaft. The adapter has a mount plate and an actuator adapter plate.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- FUEL CROSSFEED VALVE - FUNCTIONAL DESCRIPTION General The fuel crossfeed valve switch controls the crossfeed valve. When you move the switch to the open or closed position, 28v dc goes through a switch assembly to the actuator. This lets the actuator movesthe crossfeed valve to the commanded position. The printed circuit card assembly controls the operation of the crossfeed VALVE OPEN blue light. The printed circuit assembly receives fuel crossfeed valve position and fuel crossfeed valve switch position data. When the fuel crossfeed valve closes, the crossfeed VALVE OPEN light goes off. When the fuel crossfeed valve position and fuel crossfeed valve switch position disagree, the crossfeed VALVE OPEN light is bright. When the fuel crossfeed valve is open, the crossfeed VALVE OPEN light is dim.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- ENGINE FUEL SPAR VALVE General

Adapter and Shaft

The fuel spar valve controls fuel flow from the engine fuel feed manifold to the engine fuel supply line.

The adapter and shaft attaches between the front spar and the operating shaft. The adapter has a mount plate and an actuator adapter plate.

Location The left fuel spar valve is on the left wing front spar outboard of the engine strut. Access is through an access panel on the left wing leading edge. The right fuel spar valve is on the right wing front spar outboard of the engine strut. Access is through an access panel on the right wing leading edge.

The mount plate attaches to the front spar. The actuator adapter plate attaches to the mount plate with adjustment screws. Loosen the adjustment screws to rotate the actuator adapter plate. Turn the actuator adapter plate to align the butterfly valve with the actuator.

Actuator The actuator is a 28v dc motor. It has a manual override lever that permits valve operation without electrical power. The lever aligns with valve position indicators on the adapter. This shows valve position.

Motor Actuated Valve The motor actuated valve has these parts: - Valve body

The fuel spar valve actuator is interchangeable with the crossfeed valve actuator.

- Adapter and shaft - Actuator. Valve Body The valve body connects between the engine fuel feed manifold and the engine fuel supply line. The valve body has a shaft and a butterfly valve (not shown). The alignment marks show valve position.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- ENGINE FUEL SPAR VALVE - FUNCTIONAL DESCRIPTION General The engine start lever controls the engine fuel spar valve. When you move the lever to the idle or cut-off position, 28v dc goes through a switch assembly to the actuator. This lets the actuator move the engine fuel spar valve to the commanded position. The printed circuit card assembly controls the operation of the SPAR VALVE CLOSED blue light. The printed circuit assembly gets spar valve position and engine start lever position data.

When the engine fuel spar valve opens, the SPAR VALVE CLOSED light goes off. When the engine fuel spar valve position and engine start lever positions disagree, the SPAR VALVE CLOSED light is bright. When the engine fuel spar valve closes, the SPAR VALVE CLOSED light goes dim. The emergency fuel shutoff makes sure that the fuel system always has power to operate the engine fuel spar valve.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- EMERGENCY FUEL SHUTOFF BATTERY Purpose The emergency fuel shutoff battery makes sure that the fuel system always has power to close these shutoff valves:

The charge circuit uses power from dc bus 2 to charge the batteries.

- Engine fuel spar valve - APU fuel shutoff valve. Components The emergency fuel shutoff battery and charger has these components: - Aluminum case - Battery assembly - Printed circuit board assembly. Battery The battery consists of a battery assembly with an internal temperature sensor and a printed circuit board assembly. Printed Circuit Board Assembly The printed circuit board assembly has a switch circuit and a charge circuit. The switch circuit monitors the voltage of the hot battery bus. If the voltage is less than 22v dc, the switch circuit supplies power from the fuel shutoff battery to the valve actuator circuits.

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B737 NG Difference ENGINE FUEL FEED SYSTEM -- OPERATION Center Tank Engine Fuel Supply Usually all pump switches are in the ON position at the start of a flight. The center tank supplies fuel to the engines. When the center tank is empty, you turn the center tank boost pumps to the OFF position.

tank 2 supply fuel to the engines. The engines can only get suction fuel from main tanks.

If the center tank boost pump switches are on, and there is low boost pump pressure for 15 seconds, the boost pumps go off automatically to prevent overheat damage. Main Tank Fuel Supply When the center tank is empty, and the main tank boost pumps are on, pressurized fuel goes from the main tanks to the engines. Crossfeed Operation Fuel goes through the crossfeed valve to correct an imbalance between main tank 1 and main tank 2. To correct an imbalance, you open the crossfeed valve and put the boost pumps off in the fuel tank that has less fuel. Suction Operation Suction supply from a main tank occurs when all the boost pumps for that tank are off, and the crossfeed valve is closed. The bypass valve in main tank 1 and/or main tank 2 opens. This lets main tank 1 and/or main

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B737 NG Difference APU FUEL FEED SYSTEM -- INTRODUCTION Purpose The APU fuel feed system supplies fuel to the APU.

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B737 NG Difference APU FUEL FEED SYSTEM -- GENERAL DESCRIPTION General

Fuel Supply Line and Shroud

The APU fuel feed system supplies fuel from a tank to the APU.

The APU fuel feed line sends fuel from the APU fuel shutoff valve to the APU fuel control unit.

APU Fuel Feed The center tank boost pumps, or the boost pumps in main tank 1 and main tank 2 give fuel to the APU. If the boost pumps are off, the APU pulls fuel by suction from main tank 1. If a dc boost pump is installed, the dc boost pump gives fuel to the APU when the center and main tank boost pumps cannot give fuel to the left fuel feed manifold.

A shroud collects fuel leaks from the APU fuel feed line. The shroud sends the fuel overboard through a drain mast.

Control The APU electronic control unit (ECU) controls fuel flow to the APU. The ECU gets inputs from these items: - APU master switch - Fire protection system - APU sensors. The ECU uses these inputs to control the APU fuel shutoff valve. The emergency fuel shutoff battery makes sure that the fuel system always has power to close the APU fuel shutoff valve.

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B737 NG Difference APU FUEL FEED SYSTEM -- COMPONENT LOCATION General The APU fuel feed system has these components: - APU dc boost pump (optional) - APU fuel feed line - APU fuel feed line shroud - APU fuel shutoff valve. APU DC Boost Pump (optional) The APU DC boost pump is on the left wing rear spar. APU Fuel Feed Line The APU fuel feed line starts in main tank 1, goes through the center tank, then aft to the APU. APU Fuel Feed Line Shroud The APU fuel feed line shroud is around the APU fuel feed line. The shroud has a drain line that connects to a drain mast on the bottom of the left wing-to-body fairing. APU Fuel Shutoff Valve The APU shutoff valve is on the center section rear spar.

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B737 NG Difference APU FUEL FEED SYSTEM -- APU FUEL SHUTOFF VALVE General The APU fuel shutoff valve lets fuel flow from the left engine fuel feed manifold to the APU. Location The APU fuel shutoff valve is on the center section rear spar. Access is through the left wheel well. Motor Actuated Valve The motor actuated valve has a valve body and an actuator. The valve body connects to the left engine fuel feed manifold and the APU fuel feed line. The valve is a rotary type valve. The alignment marks show valve position. The actuator is a 28v dc motor. It has a manual override lever that permits valve operation without electrical power. The lever aligns with valve position indicators on the adapter. This shows valve position.

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B737 NG Difference APU FUEL FEED SYSTEM -- APU FUEL SHUTOFF VALVE - FUNCTIONAL DESCRIPTION Control

- Engine/APU fire detection module sends a fire signal to the ECU

The APU electronic control unit (ECU) controls the APU fuel shutoff valve. The ECU receives input from these components:

- ECU receives an out-of-limits signal from APU sensors.

- APU switch - APU fire control handle - APU fire switch handle - Engine/APU fire detection module - APU sensors.

The ECU uses these inputs to open or close the APU fuel shutoff valve. The APU fuel shutoff valve opens when all of these conditions occur: - APU master switch is in the START or ON position - APU fire control handle and the APU fire switch handle are in the NORMAL positions - Engine/APU fire detection module does not send a fire signal to the ECU - ECU does not receive an out-of-limits signal from the APU sensors. The APU fuel shutoff valve closes when one or more of these conditions occur: - APU master switch is in the OFF position - APU fire control handle is in the FIRE position - APU fire switch handle is in the FIRE position

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B737 NG Difference APU FUEL FEED SYSTEM -- APU DC BOOST PUMP General The APU dc boost pump supplies fuel to the APU. The APU dc boost pump has a pump assembly and a housing assembly. The housing assembly is in the fuel tank. The pump assembly attaches to the outer side of the fuel tank. You can remove the pump assembly with fuel in the fuel tank. The APU dc boost pump is on the left wing rear spar.

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B737 NG Difference APU FUEL FEED SYSTEM -- APU DC BOOST PUMP - FUNCTIONAL DESCRIPTION General The APU dc boost pump supplies fuel to the APU when the center and main tank boost pumps cannot supply fuel to the APU.

The fuel control panel receives low pressure signals from the boost pump low pressure switches. The fuel control panel also receives a crossfeed valve position signal from the crossfeed valve.

APU DC Boost Pump On - Condition 1 The APU dc pump comes on when these conditions occur: - Main tank 1 boost pumps have low pressure - Left center tank boost pump has low pressure - Crossfeed valve is closed - APU master switch is in the ON position - APU fire switch is in the NORMAL position - ECU finds no protective shutdown faults. APU DC Boost Pump On - Condition 2 The APU dc pump also comes on when these conditions occur: - Main tank 1 boost pumps have low pressure - Main tank 2 boost pumps have low pressure - Center tank boost pumps have low pressure - Crossfeed valve is open - APU master switch is in the ON position - APU fire switch is in the NORMAL position - ECU finds no protective shutdown faults. Manual No : JCT – 0151

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B737 NG Difference FUEL QUANTITY INDICATING SYSTEM -- INTRODUCTION Fuel Quantity Indicating System (FQIS) The FQIS measures fuel weight in the fuel tanks. The fuel quantity in the main tanks and in the center tank shows on the primary engine display of the common display system (CDS). The refueling panel indicators show the quantity of fuel in each tank.

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B737 NG Difference FQIS -- GENERAL DESCRIPTION General The fuel quantity indicating system (FQIS) receives information from the fuel quantity processor unit (FQPU), to be displayed on the engine display. The FQPU calculates the total fuel weight and supplies this value to the FMCS. The fuel quantity processor unit (FQPU) calculates the fuel weight in the main tanks and the center tank. Each processor uses a set of tank units and compensators to calculate fuel weight. The FQPU supplies a total airplane fuel quantity to the flight management computer system (FMCS). The fuel quantity of the main tanks and center tanks shows on the common display system (CDS).

When the tank quantity and the preselect value are in agreement, the indicator stops the refueling operation for that tank. The fuel quantity processor unit sends excitation to and receives signals from the tank units, compensators, and densitometers. The fuel quantity processor unit uses these signals to calculate the fuel quantity in each tank.

Each refueling indicator has an overfill indication. The fuel quantity indication flashes at a 1-second rate when the fuel in the tank is at more than the maximum capacity rating.

The fuel quantity in each tank shows on the refueling indicators. The left and right indicators show the main tank quantity. The center tank indicator shows the center fuel tank quantity. General Description The fuel quantity indicators on the refueling panel have a preselect function. The fuel quantity for a tank shows in the top part of the display. A preselect fuel quantity value can be entered in the bottom part of the indicator display. The indicators receive fuel quantity data from the FQPU. A comparator circuit card in the indicator compares the fuel quantity of a tank with the preselect value for the same tank.

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B737 NG Difference FQIS -- TANK UNITS AND COMPENSATORS General There are 32 tank units in the fuel tanks. There are 12 tank units in main tank 1, and 12 tank units in main tank 2. There are 8 tank units in the center tank. There is one compensator in each tank. Tank Units The tank units measure fuel volume. The fuel quantity processor sends a low impedance excitation signal to the tank units. The tank units send back a one high impedance signal to the processor. This high impedance return signal is in proportion to fuel volume for the tank. Compensators The compensators correct for differences in fuel properties. The fuel quantity processor sends a low impedance signal to each compensator. The compensators send back a high impedance signal to the processor. This high impedance return signal is in proportion to the dielectric of the fuel. The dielectric of fuel is proportional to fuel density. Each compensator is in the low point of its fuel tank. For most operations, the compensator is below the fuel level. The high impedance return signal from each compensator changes only for differences in fuel dielectric.

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B737 NG Difference FQIS -- WIRE HARNESSES General There is one wire harness in each tank. Each wire harness connects to the fuel tank units and the compensator in each tank. Each wire harness connects to a feed through connector inside the fuel tank. Outside the tank, each spar connector attaches to a busing plug. Each busing plug connects to the fuel quantity processor unit.

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B737 NG Difference FQIS -- FUEL QUANTITY PROCESSOR UNIT Purpose The fuel quantity processor unit does these functions: - Calculates fuel weight in each tank - Calculates the total fuel weight - Sends fuel weight to the common display system - Sends fuel weight to the fueling panel (P15) - Sends fuel weight to the flight management computer - Monitors the fuel system for faults - Stores faults in non-volatile memory - Sends fault data to the control display units. Location

The fuel quantity processor unit is on the aft bulkhead of the forward equipment center.

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B737 NG Difference FQIS -- FUEL QUANTITY PROCESSOR UNIT - POWER General The fuel quantity processor unit (FQPU) connects to two isolated 28v dc power sources at a time. The fuel quantity processor unit operates when one or two of the sources have power.

When the fueling indication test switch is in the FUEL DOOR BYPASS SWITCH position, processor unit power comes from the 28v dc hot battery bus.

Power Sources The FQPU can receive power from one of these three sources: - 28v dc bus 1 - 28v dc hot battery bus - 28v dc battery bus. The power source normally available is the 28v dc battery bus. Transformer rectifier 3 (TRU 3) is the normal power source for this bus. The battery or battery charger can also supply power to this bus if TRU 3 power is not available, and the battery switch is in the ON position. When the fueling station door is in the closed position, processor unit power can come from dc bus 1. AC power must be on the airplane to supply power to this bus. When the fueling station door is open, and ground power is available, processor unit power can come from the 28v dc hot battery bus. The battery supplies power to this bus. It is not necessary to put the battery switchin the ON position for the battery to supply power to this bus.

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B737 NG Difference FQIS -- FUEL QUANITIY PROCESSOR UNIT - FUNCTIONAL DESCRIPTION General

BITE Display Card

The fuel quantity processor unit (FQPU) has 4 signal conditioner circuit cards (SCCC) and a BITE display card (BDC). The FQPU calculates the weight of the fuel for the main tanks and the center tank.

The BDC does these functions:

Fuel quantity for the main tanks and the center tank shows on the primary engine display of the common display system (CDS).

- Keeps fault data in non-volatile memory - Sends a signal to each SCCC to start a real-time test for fault isolation -Sends and receives fault data with the flight management computer for fault isolation.

Signal Conditioner Circuit Cards There is 1 SCCC for each fuel tank. The main tank and center tank SCCCs do these functions: - Send a low Z signal to the tank units and compensator - Receive the high Z return signal from the tank units and compensators

- Calculates fuel density to improve system accuracy (if installed) - Calculate total fuel weight for its tank - Change analog signals to ARINC 429 signals - Send tank fuel weight data to the DEUs

- Send fault data to the BDC. The tank 2 SCCC also sends total fuel tank weight to the FMC.

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B737 NG Difference FQIS -- FUEL QUANTITY INDICATIONS General Main fuel tank and center tank quantity show on the primary engine display and the refuel panel.

The fuel quantity display shows in a digital format. A totalizer display shows the total quantity of all 3 airplane fuel tanks.

Fuel quantity shows in pounds or kilograms. Fuel Configuration Messages Fuel configuration messages show on the CDS. These messages show a problem with the configuration of the fuel system.

The LOW message shows that main tank 1 or main tank 2 has less than 2000 lb (907 kg) of fuel. This message goes away when there is more than 2500 lb (1133 kg) of fuel in that tank. There must be a low fuel condition for 30 seconds before the LOW message shows. The IMBAL message shows when there is a difference of 1000 lb (453 kg) between main tank 1 and main tank 2. The message goes away when the difference between tanks is 200 lb (90 kg) or less. The IMBAL message only shows when the airplane is in the air. The IMBAL message does not show when the LOW message shows. There must be an imbalance condition for 60 seconds before the IMBAL message shows. The CONFIG message shows for these conditions: - 1600 lb (725 kg) or more of fuel in the center tank - 2 center tank boost pumps are off - One or the other engine is in operation. Manual No : JCT – 0151

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B737 NG Difference FQIS -- TRAINING INFORMATION POINTS - FQIS BITE TEST MAIN MENU PAGES General

Ground Test Pages

Use the control display units (CDUs) to do troubleshooting for the fuel quantity indicating system. The CDU shows real time and recorded system fault data. The fuel quantity processor monitors and stores the data that shows on the CDU. Use the CDU to see the FQIS BITE test pages only when the airplane is on the ground.

The ground test pages let you do a test of the FQIS processor.

Main Menu Pages

The input monitoring pages show real time fuel quantity data for each fuel tank.

The FQIS BITE test main menu pages allow selection of other FQIS BITE test pages. These are the FQIS BITE test pages: - Current status

IDENT/CONFIG Pages The IDENT/CONFIG pages show data from the configuration of the fuel quantity processor unit. Input Monitoring Pages

Erase Fault History Pages The erase fault history pages provide for erasing recorded fault data from the fuel quantity processor memory.

- Inflight faults/fault history - Ground test - Ident/config - Input monitoring - Erase fault history. Current Status Pages The current status pages show fuel indication system faults that currently show on the airplane.

Inflight Faults/Fault History Pages The inflight faults/fault history pages show recorded FQIS faults from flight legs before.

Manual No : JCT – 0151

for training purposes only 108

Date : 12 June 2012

B737 NG Difference

Manual No : JCT – 0151

for training purposes only 109

Date : 12 June 2012

B737 NG Difference FUEL TEMPERATURE INDICATING SYSTEM -- INTRODUCTION Purpose The fuel temperature indicating temperature in main tank 1.

Training Information Point system

shows

fuel

When there is no electrical power, the pointer goes off scale at the negative side of the indicator.

Location The fuel temperature bulb is on the rear spar on main tank 1. The fuel temperature indicator is on the fuel system panel on P5. Components The fuel temperature indicator is a resistance ratiometer instrument. The fuel temperature bulb is a resistance unit. The resistance of the fuel temperature bulb changes with fuel temperature. It is not necessary to remove fuel from main tank 1 to remove the fuel temperature bulb. Operation The fuel temperature indicator receives 28v ac. The fuel temperature indicator sends a dc signal to the fuel temperature bulb. The fuel temperature bulb resistance changes this signal before it goes back to the fuel temperature indicator.

Manual No : JCT – 0151

for training purposes only 110

Date : 12 June 2012

B737 NG Difference

Manual No : JCT – 0151

for training purposes only 111

Date : 12 June 2012

B737 NG Difference FUEL MEASURING STICK - MEASURING STICKS General The fuel measuring sticks are used to manually measure fuel quantity. There are six measuring sticks in main tank 1 and main tank 2. Each fuel measuring stick is on a fuel tank access door. The fuel measuring sticks are numbered 3 through 8, from inboard to outboard on each tank. There are four fuel tank measuring sticks in the center tank. Two fuel tank measuring sticks are on fuel tank access panels and two are on the wing skin. The center tank fuel measuring sticks are numbered 1 and 2, from inboard to outboard on the left and right side of the tank. The inner sticks have graduation marks that show fuel height in linear units. There are two inclinometers, one for airplane pitch, one for airplane roll, in the main landing gear wheel well. There is also plumb bob attachment and a leveling scale in the right main wheel well. Use the plumb bob and leveling scale to determine airplane pitch and roll. Use fuel height linear unit measurement and airplane pitch and roll to measure fuel quantity. Chapter 12 of the AMM Part II or the 737 Fuel Measuring Stick Manual, has conversion tables that change linear units, fuel height, and airplane pitch and roll into fuel quantity.

Manual No : JCT – 0151

for training purposes only 112

Date : 12 June 2012

B737 NG Difference

Manual No : JCT – 0151

for training purposes only 113

Date : 12 June 2012