B767 - Fuel System

B767/28/101 Fuel System

Boeing 767-200/300

Fuel System Training manual For training purposes only LEVEL 1

ATA 28

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This publication was created by Sabena technics training department, Brussels-Belgium, following ATA 104 specifications. The information in this publication is furnished for informational and training use only, and is subject to change without notice. Sabena technics training assumes no responsibility for any errors or inaccuracies that may appear in this publication. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Sabena technics training.

Contact address for course registrations course schedule information Sabena technics training [email protected]

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LIST OF EFFECTIVE PAGES 1................................................ 12 - 04 - 2012 2................................................ 12 - 04 - 2012 3................................................ 12 - 04 - 2012 4................................................ 12 - 04 - 2012 5................................................ 12 - 04 - 2012 6................................................ 12 - 04 - 2012 7................................................ 12 - 04 - 2012 8................................................ 12 - 04 - 2012 9................................................ 12 - 04 - 2012 10.............................................. 12 - 04 - 2012 11.............................................. 12 - 04 - 2012 12.............................................. 12 - 04 - 2012 13.............................................. 12 - 04 - 2012 14.............................................. 12 - 04 - 2012 15.............................................. 12 - 04 - 2012 16.............................................. 12 - 04 - 2012 17.............................................. 12 - 04 - 2012 18.............................................. 12 - 04 - 2012 19.............................................. 12 - 04 - 2012 20.............................................. 12 - 04 - 2012 21.............................................. 12 - 04 - 2012 22.............................................. 12 - 04 - 2012 23.............................................. 12 - 04 - 2012 24.............................................. 12 - 04 - 2012 25.............................................. 12 - 04 - 2012 26.............................................. 12 - 04 - 2012 27.............................................. 12 - 04 - 2012 28.............................................. 12 - 04 - 2012 29.............................................. 12 - 04 - 2012 30.............................................. 12 - 04 - 2012 31.............................................. 12 - 04 - 2012 32.............................................. 12 - 04 - 2012 33.............................................. 12 - 04 - 2012 34.............................................. 12 - 04 - 2012 35.............................................. 12 - 04 - 2012 36.............................................. 12 - 04 - 2012 37.............................................. 12 - 04 - 2012 38.............................................. 12 - 04 - 2012 39.............................................. 12 - 04 - 2012 40.............................................. 12 - 04 - 2012 41.............................................. 12 - 04 - 2012

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TABLE OF CONTENTS 1. INTRODUCTION. ...................................................................................................................6 1.1. General................................................................................................................................6 1.2. Fuel Components - Left Rear Spar. .....................................................................................10 1.3. Fuel Components - Right Rear Spar. ...................................................................................10 2. FUEL TANKS. .......................................................................................................................12 2.1. Construction and Location. ................................................................................................12 3. FUEL VENT SYSTEM............................................................................................................14 3.1. Construction and Components. .........................................................................................14 3.2. Float Valves. .......................................................................................................................14 4. PRESSURE FUELING SYSTEM. ............................................................................................16 4.1. General Configuration. ......................................................................................................16 4.2. Fueling Station. ..................................................................................................................18 4.3. FQIS Load Select Fuel Quantity Indicator. ............................................................................18 4.4. Overwing Fueling Ports. .....................................................................................................20 5. ENGINE FUEL FEED SYSTEM. .............................................................................................22 5.1. General..............................................................................................................................22 5.2. Engine Fuel Feed System Operation....................................................................................22 5.3. Motor-Actuated Valves.......................................................................................................24 5.4. Automatic Sumping Jet Pumps...........................................................................................26 5.5. Transfer Jet Pumps. ............................................................................................................28 6. APU FUEL FEED SYSTEM. ...................................................................................................32 6.1. General..............................................................................................................................32 6.2. Defueling. ..........................................................................................................................36 7. FUEL JETTISON SYSTEM. ....................................................................................................38 7.1. General Description. ..........................................................................................................38 7.2. Fuel Jettison System Operation...........................................................................................38 8. FUEL QUANTITY INDICATING SYSTEM (FQIS)...................................................................40 8.1. Design Features. ................................................................................................................40

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LIST OF ILLUSTRATIONS APU BOOST PUMP CONTROL AND OPERATION ..................................................................... 34 APU FUEL FEED SYSTEM ........................................................................................................ 33 AUTOMATIC SUMPING JET PUMPS ........................................................................................ 27 DEFUELING SYSTEM............................................................................................................... 37 ENGINE FUEL FEED SYSTEM AND OPERATION ........................................................................ 30 FQIS LOAD SELECT FUEL QUANTITY INDICATOR .................................................................... 19 FUELING STATION .................................................................................................................. 19 FUEL JETTISON SYSTEM AND OPERATION .............................................................................. 39 FUEL QUANTITY INDICATING SYSTEM.................................................................................... 41 FUEL SYSTEM........................................................................................................................... 7 FUEL SYSTEM PANELS .............................................................................................................. 9 FUEL TANKS ........................................................................................................................... 13 FUEL VENT SYSTEM AND FLOAT VALVES ................................................................................ 15 LEFT REAR SPAR - FUEL COMPONENTS .................................................................................. 11 MOTOR ACTUATED VALVES ................................................................................................... 25 OVERWING FUELING PORTS................................................................................................... 21 PRESSURE FUELING SYSTEM .................................................................................................. 17 RIGHT REAR SPAR - FUEL COMPONENTS................................................................................ 11 TRANSFER JET PUMPS ............................................................................................................ 29

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ABBREVIATIONS AND ACRONYMS ACMS APU ARINC AUX BATT CDCCL CHAN CONFIG CTR DFDAU EICAS FMC FQIS IDG IFQC IND IOC L LRU MEC NOZ NVM OVRD QTY R SYS TYP WSL XFR

Aircraft Condition Monitoring System Auxiliary Power Unit Aeronautical Radio Incorporated Auxiliary Battery Critical Design Configuration Control Limitations Channel Configuration Center Digital Flight Data Acquisition Unit Engine Indication and Crew Alerting System Flight Management Computer Fuel Quantity Indicating System Integrated Drive Generator Individual Fuel Quantity Cards Indication Indirect Operating Cost Left Line Replaceable Unit Main Engine Control Nozzle Non Volatile Memory Override Quantity Right System Typical Wetted Sensing Lengths Transfer

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1. INTRODUCTION. The boeing 767 fuel system includes the fuel tanks, a vent system, a fueling system, a feed system with automatic sumping, defueling valves, a fuel jettison system, and a fuel quantity indicating system (FQIS).

1.1. General. Fuel Tanks. All fuel for the engines and APU is stored within the wing. The three tanks, left main, right main, and center auxiliary are of wet wing construction. Baffle ribs in the main tanks control outboard flow. Outboard of both main tanks is a surge tank. The surge tanks contain overflow and prevent fuel spills. The surge tanks drain into the center auxiliary tank and are normally empty. Vent System. The vent system maintains near ambient atmospheric pressure within the tanks. A vent scoop in each wing creates a slightly positive pressure during flight to its associated surge tank. Vent channels connect each surge tank to the main and auxiliary fuel tanks. A flame arrester is mounted in both vent scoop tubes. Backup pressure relief valves are provided. Fueling System. The fueling system includes a manifold with six fueling valves inside the tanks and a fueling station on the left wing leading edge. The fueling valves are controlled by the fuel quantity indicating system (FQIS) to allow versatility in fueling operations. An overfill sensor in each surge tank terminates fueling operations should the tanks overfill. An overwing fill port is located on the upper wing surface for both main tanks. Pump priming and FQIS component washing is also accomplished during fueling. Feed System. The fuel feed system supplies fuel to the two main engines and the APU. Two AC boost pumps are installed in each main tank. Two AC override pumps are installed, one per side, in the center auxiliary tank. A bypass valve in each main tank allows suction flow from the main tanks. A DC pump pressure feeds the APU automatically when the AC pumps are not operating. Dual crossfeed

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valves interconnect the normally isolated left and right feed manifolds. This allows any tank to feed either engine if desired. Automatic jet pumps prevent water and contaminates from accumulating in tank low points and transfer remaining fuel into the main tanks from the center auxiliary tank after the main tanks are depleted to approximately one-half full. Defueling. The defueling valves interconnect the feed system and the fueling system. This allows defueling and fuel transfer operations on the ground only. Fuel Jettison. A fuel jettison system is installed to rapidly reduce the gross weight of the aircraft. Two jettison pumps operate along with the center override pumps, to jettison center auxiliary tank fuel overboard. Controls for the system are located on the flight deck. Fuel Quantity Indicating System (FQIS). The FQIS is a microprocessor controlled capacitance type fuel quantity measuring system. The FQIS requires only 28V DC power for operation. A direct digital display of fuel weight is provided in the flight compartment and at the fueling station. Tank units and compensators provide volume measurement. Densitometers, one in each tank, provide fuel density signals. The FQIS also controls the fueling valves to allow overfill protection and automatic fueling termination at preselected quantity levels. Measuring Sticks. Magnetic dripless type measuring sticks are mounted in the lower wing surfaces of each tank to provide an alternate method of determining fuel quantity.

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FUEL SYSTEM PANELS

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1.2. Fuel Components - Left Rear Spar.

1.3. Fuel Components - Right Rear Spar.

The following fuel system components are located on the left rear spar :

The following fuel system components are located on the right rear spar :

- Fueling valves (2 main, 1 center), - Left defueling valve, - Boost, override, and fuel jettison pump pressure switches, - Left engine fuel shutoff valve (spar valve), - FQIS wiring harness connections (left main and left center), - Left main tank densitometer connector, - APU DC pump, - APU fuel shutoff valve, - Left jettison transfer valve, - Fuel crossfeed valves, - Temperature bulb, - Left jettison nozzle valve.

- Fueling valves (2 main, 1 center), - Right defuel valve, - Boost, override, and fuel jettison pump pressure switches, - Right engine fuel shutoff valve (spar valve), - FQIS wiring harness connections (right main and right center), - Right main tank and center tank densitometer connectors, - Right jettison transfer valve, - Right jettison valve.

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RIGHT REAR SPAR - FUEL COMPONENTS LEFT REAR SPAR - FUEL COMPONENTS EFFECTIVITY ALL

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2. FUEL TANKS. 2.1. Construction and Location. All three fuel tanks are constructed by sealing the primary wing structure with sealant. The tanks are formed by the front and rear spars, the top and bottom wing skins, and by selected wing ribs. Main Tanks. The left and right main tanks are located between rib 3 and rib 31 in both wings. Dry bays are located in both wing leading edges over the engine hot sections to prevent fuel leakage from contacting the engine. Rib 5 and rib 18 are sealed, and have free-swinging check valves in the bottom to allow inboard fuel flow while preventing outboard fuel flow. These fuel dams control flow to prevent uncovering the pump inlet ports, and to prevent fuel weight shifts. The main tanks may be fueled by use of an overwing port near the leading edge between rib 23 and rib 24. Center Auxiliary Tanks. The center auxiliary tank is between ribs 3 in the wing and through the fuselage. There is no dry bay in this tank. Surge Tanks. The surge tanks are located between rib 31 and rib 34 in both wings. These normally empty tanks are designed to contain overflow to prevent fuel spillage.

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Access. Access to all tanks and the dry bays is through oval cutouts in the lower wing surface. In selected cases (ribs 1, 2, 4, 5 and 9), openings in the rib allow access to adjoining rib sections. A cover panel is installed over the opening in rib 5, to prevent fuel slosh through the opening. The panel must be removed to gain access to the inboard tank area. The cutouts vary in size, with the smaller ones outboard. Other components, such as measuring sticks and pressure relief valves are installed on selected access doors. The center section has one access door in the lower right corner, located just forward of the right air conditioning bay area. Sump drains. Identical sump drain valves are located in the low point of both main tanks, both surge tanks, and in each side of the center auxiliary tank outboard of the S.O.B . rib. In addition, a sump drain valve with a tube attached is located inboard of each S.O.B. rib. These are accessed by use of a door in the wing root fairing. There are a total of eight drain valves. These allow fuel sampling, and draining of residual fuel. In addition, the dry bay for the engine hot section has two drain holes with flame arresters.

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FUEL TANKS

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3. FUEL VENT SYSTEM. The fuel vent system is designed to maintain the fuel tanks at near ambient atmospheric pressure under all operating conditions. Overpressuring the tanks could cause structural damage. Underpressurizing could cause component malfunction and engine fuel starvation.

3.1. Construction and Components. Three vent channels in each wing are formed by hat section stringers on the inside upper wing skin. Open-ended vent tubes are mounted on the bottom of the channels to provide porting to the surge tank in nose-high attitudes. The vent channels are ported to the surge tanks. The vent scoop is installed in the lower wing surface and is connected to a tube and standpipe in the surge tank. A flame arrester is installed in each of the vent scoop tubes. Float valves are installed on the dive ports in the tanks to prevent fuel from flowing into the surge tanks when the ports are immersed during nose-high attitudes. Float drains allow fuel to drain into the tanks that would otherwise be trapped in the vent tubes. A pressure relief valve in each tank provides backup venting should a vent scoop or flame arrester become obstructed.

3.2. Float Valves. Fuel Vent Channel Float Valve. The four vent channel float valves are hinge-mounted on the vent channels to close the ports when immersed in fuel to prevent fuel from entering the channel and flowing to the surge tank. The valve is fuel-level actuated. Fuel Vent Float Valve (Rib 18). The two vent float valves are hinge mounted on the upper forward section of rib 18. The valve closes a port through rib 18 when immersed in fuel to prevent outboard fuel flow through the port. The valve opens the port when not immersed to allow air to vent outboard during fueling.

Main Tank Venting. Two hat section stringers provide ventilation for all three tanks. A float valve on baffle rib 18 allows air to vent to the outboard side of the rib to prevent a trapped air bubble from forming during fueling. This float valve closes when immersed in fuel to prevent outboard fuel flow. The inboard side of rib 18 is ported to the outboard side of rib 18 to allow fuel to flow through the vent channels during fueling to completely service the tank should the outboard fueling valve be inoperative. Center Auxiliary Tank Venting. The center auxiliary tank is crossvented to minimize fuel drainage into the surge tanks because of wing-low attitudes and maneuvering on the ground.

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4. PRESSURE FUELING SYSTEM. In addition to fueling and defueling the airplane, the pressure fueling system primes the boost and override pumps.

4.1. General Configuration. Fueling, fuel transfer, and defueling are accomplished and controlled from a single fueling station located on the left wing. The fueling station includes a fueling control panel (P28) and two fueling adapters. Each fueling adapter has a cap. A light on the door provides illumination, and indication of station power.

Fueling Capabilities. Normal fueling is accomplished from the fueling station with 28V DC power. The fuel quantity indicating system (FQIS) interfaces with the fueling system to allow automatic fueling shutdown at preselected quantities or when the tanks are full by volume. Backup overfill protection is supplied by a separate card located in the P50 card file and a sensor in each surge tank.

The fueling manifold is located near the rear spar inside the tank. It includes six fueling valves, a manifold vacuum valve, two manifold drain valves, a pressure relief valve and two defuel valves. Fueling check valves prevent backflow. Pressure Fueling Valves. There are two fueling valves for each tank. These valves are fuel pressure actuated, solenoid controlled valves. The solenoid is controlled by the FQIS microprocessor through a switch on the P28 panel. A knurled knob on the valve allows the valves to be manually opened without solenoid power. Fuel Manifold Draining. The two manifold drain valves drain the manifold into the center auxiliary tank after fueling. These close during fueling to prevent undesired fueling flows. The single manifold vacuum valve vents air into the manifold. It closes during defueling to prevent sucking air into the manifold.

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4.2. Fueling Station.

4.3. FQIS Load Select Fuel Quantity Indicator.

Open the fueling station door by pushing the two guide release fasteners. Inside are two fueling adapters, the fueling control panel, a panel light for illumination and power indication, an interphone jack, and two grounding jacks.

The load select and fuel quantity indicators are mounted on the fueling control panel in the fueling station. There is one indicator for each of the three tanks.

Fueling Control Panel. The fueling control panel contains the switches, pushbuttons, controls, and indications necessary to fuel and defuel the airplane in normal operations. A guarded switch allows power selection of 28V DC sources. Three FQIS load select indicators provide LCD indication of fuel quantity. A load select control allows preselecting desired fuel weight in any tank. Toggle switches allow manual control of fueling. Test and reset pushbuttons for FQIS and overfill systems are available. Two guarded defuel valve switches allow control of defueling operations. Power. 28V DC power from the ground handling bus is available, when the station door is open, by a magnetic reed switch near the door stay-open catch. Place the POWER switch to BATT to supply hot battery bus power. Flight compartment access is not required. Fueling Adapters. The fueling adapters allow connection of standard fueling nozzles. Defueling requires rotating a slot 90° to the DEFUEL position prior to connecting the nozzle.

Liquid Crystal Displays (LCD). There are two fuel quantity displays on each indicator. The three digit displays are light numerals with a dark background. The upper display indicates the fuel weight in the tank. The lower display indicates the selected fuel weight for termination of fueling. LCD’s tend to fade and may not be readable in very cold weather. An automatic heater, powered by fueling station power, warms the LCD’s. Indicator Operation. The indicators operate only when the FQIS processor unit has power and when the fueling station has power (door open). Except for the LCD heaters, lighting, and power, all signals originate from the FQIS processor. Indicator faults are not stored in the processor NVM. Indicator Test. When the IND TEST button is pushed, first the indicators go blank, then 88.8 appears followed by fault codes or the normal fuel weight display as appropriate. Note this indicator test sequence is the same as the flight deck indicator test sequence. See Flight deck indicator for details. Mounting. The indicators are friction-clamped in the fueling control panel. To remove an indicator, loosen the four screws on the panel face. The indicators are LRU’s.

Fueling adapter caps cover the fueling adapters on aircraft equipped with fuel jettison. The caps supply a secondary seal to the fueling manifold.

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4.4. Overwing Fueling Ports. The overwing fueling ports provide a method of fueling main tanks without utilizing the pressure fueling station. The ports may also be used to inspect a portion of the tank visually. Location. Two ports, one on each wing, at wing station 785.2 between rib 23 and rib 24 are available. Access is from the wing leading edge. A grounding point for the nozzle is located close to the port. Filler Cap. The filler cap seals the fueling port. Venting is not provided. A lanyard prevents the cap from being lost when removed. Lift and rotate the handle to remove the cap. Fueling Port. The fueling port is installed using O-ring seals, a seal ring and a retaining nut. The tanks will contain 5925 gallons when fueled to the port level. The tanks will hold 6070 gallons when fueled with the pressure fueling system. The caps should not be removed when the mains are full to prevent spillage.

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5. ENGINE FUEL FEED SYSTEM. 5.1. General.

5.2. Engine Fuel Feed System Operation.

The fuel feed system is designed to supply fuel to the engines and APU. This system is also utilized to transfer fuel from tank-to-tank on the ground. Automatic sumping jet pumps are powered by the feed system to prevent water and contamination buildup in the tanks. Transfer jet pumps are also powered by the feed system to transfer the last remaining fuel in the center auxiliary tank into the main tank when the main tank is less then approximately one-half full.

Normal operation - Fuel in all three tanks. During normal operation, all boost and override pumps are turned on, the crossfeed valves are closed and the spar valves are open. Since the override pumps develop higher pressure than the boost pumps, the boost pump check valves are back -pressured closed and fuel is drawn from the center auxiliary tank.

Configuration. The feed manifold and most system components are located within the tanks. The left and right manifolds are interconnected by dual crossfeed valves. There are two AC boost pumps in a common dry bay housing on the lower surface of each main tank. There is one AC override pump and one fuel jettison pump in a dry bay housing in the lower wing surface on each side of the center auxiliary tank. A bypass valve allows suction flow from both main tanks. A fuel shutoff valve shuts off fuel to the engine. The crossfeed valves, engine fuel shutoff valves, defuel valves, jettison valves, and APU fuel shutoff valve are dc motor actuated. They are all mounted on the rear spar.

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Normal operation - Center Auxiliary Tank Empty. When the center auxiliary tank is empty the amber PRESS lights come on for both override pumps. The override pumps are then turned off. The boost pumps then automatically feed the engines when the override pumps stop developing pressure, assuring uninterrupted flow. One boost pump can provide sufficient flow for both engines, if necessary. Crossfeed Operation. Fuel unbalance, or multiple pump failures on one side are overcome by opening a crossfeed valve and controlling boost and override pumps. Both engines may be fed from one tank if desired. Airborne tank-to-tank transfer cannot be accomplished. Suction Feed. The bypass valve is normally backpressured closed by pump output pressure. When the boost and override pumps are not operating, the engine driven fuel pump draws fuel through the bypass valve. The EICAS caution message L (R) FUEL SYS PRESS advises of this condition.

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5.3. Motor-Actuated Valves. The motor-actuated valves on the engine feed system include the engine fuel shutoff valves (spar valves), the crossfeed valves, and the defuel valves. Each valve has three sub-assemblies; the valve body, an adapter and shaft assembly, and a 28V DC permanent magnet motor actuator. The valve bodies and actuators are interchangeable between installations.


Actuator Replacement. The actuator is replaceable without defueling. It mounts to an adapter plate with 4 screws. It should be installed in the valve closed position. Do not loosen the three adjustment screws, because the valve closed alignment marks on the valve body are not visible outside of the tank. Realignment requires tank access.

Valve Body. The valve bodies are mounted in-line on the engine manifold, inside the tanks, using two couplings. The body has a 4 hole mounting flange, a thermal relief, and a splined operating shaft with a universal joint. One spline is missing to assure proper indexing on installation. The thermal relief valve is threaded to allow installation of a plug for pressure testing. Alignment marks indicate that the valve is closed, because the valve does not hard stop either open or closed. Adapter and Shaft Assembly. The adapter and shaft assembly is custom-fit to each installation. The assembly includes a mount plate, an adapter plate, and a shaft with a universal joint. The actuator and adapter have two splines omitted to assure proper indexing. Loosening three adjustment screws allows the adapter plate to be rotated in slots with respect to the mount plate. During the original installation of the adapter and shaft assembly, the adapter plate can be rotated with the actuator installed, and in the valve closed position, to align the marks on the valve body. Three screws on the adapter plate can be loosened to allow the alignment. Motor Actuator. All motor actuator on the fuel system are mounted in the wheel wells on the rear spar, are interchangeable, and are powered by 28V DC. A manual override lever allows the actuator to be operated without electrical power. This lever also indicates valve position. Cycle time between limits is approximately 2 to 3 seconds.

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5.4. Automatic Sumping Jet Pumps. The automatic sumping jet pumps draw fuel and contaminates from the tank low points. They discharge near the boost and override pump inlets, allowing the contaminates to be drawn in and pass through the engine before an accumulation can occur. Physical Description/Features. Each of the six rib-mounted jet pumps has five inlet ports. A screened tube connects to each port to draw from the tank low point between stringers. In the center auxiliary tank, two of the inlets are longer than the rest to scavenge fuel from the bays inboard of the side of body rib. There is a connection for the motive flow to power the pump, and for discharge. Location and Installation. There are six jet pumps, three per side. The two main tank jet pumps are mounted on rib 3. The center auxiliary tank jet pumps are mounted on rib 2, one in each side. The housing is mounted to the rib. The pump assembly mounts to the housing on the opposite side of the rib.

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5.5. Transfer Jet Pumps. The transfer jet pumps are designed to siphon any residual fuel from the center auxiliary tank to the main tanks after the override pumps are turned off during normal operation (after the override pump low pressure lights come on). Location. One jet pump is located in each side of the center auxiliary tank, just inboard of the side-of-body rib. A float valve is located outboard of rib 3 in each main tank. Physical Description/Features. The pumps are of the jet aspirator type. The aft main tank boost pumps supply the motive force to power the two transfer jet pumps. A ball check valve prevents backflow through the induced port. Operation. Fuel pressure is present at the motive port whenever the aft main tank pumping units are operating. A float valve in each main tank closes the discharge port until the main tank is depleted to approximately one-half full. When the discharge port is open, motive flow aspirates fuel from the center tank through the induced port, and transfers this fuel to the main tanks through the discharge port. Operation is thus completely automatic, as a function of the float valve, and is unmonitored. To operationally check the transfer jet pumps, the auxiliary fuel tanks must contain at least 1,000 Kg. of fuel and each main tank must contain less than 9,000 Kg. of fuel. To verify operation of the float valves (closure), the auxiliary fuel tanks must contain at least 1,000 Kg. of fuel and each main tank must contain at least 11,500 Kg. of fuel.

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TRANSFER JET PUMPS EFFECTIVITY ALL

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ENGINE FUEL FEED SYSTEM AND OPERATION EFFECTIVITY ALL

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6. APU FUEL FEED SYSTEM. 6.1. General. The APU is normally fed from the left engine feed manifold. The right engine feed manifold may also be used when a crossfeed valve is open. When fuel pressure is unavailable from the engine feed manifold, an APU DC pump located on the left rear spar will automatically pressure-feed the APU. APU DC Pump. The APU DC pump draws fuel from the left main tank only. It operates on 28V DC power from the battery bus automatically. There are no controls in the flight compartment. A pressure switch on the pump inputs to the EICAS, which displays the maintenance message DC FUEL PUMP ON when appropriate. APU Fuel Shutoff Valve. The APU fuel shutoff valve is a 28V DC motor actuated unit that operates automatically when the APU is started or shut down. APU Fuel Supply Line. The fuel supply line is a solid aluminum tube routed through the left SOB rib into the dry center area and out the top to a special fitting between the top of the center section and passenger floor. This fitting connects a Kevlar braid one-piece plastic coated flex-line, a rigid aluminum shroud to contain flex-line leaks, and a drain line to the mast located aft of the left wheel well. The flex-line is laying inside the shroud unsupported. Access to the fitting for flex-line replacement requires removal of a section of the passenger floor.

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APU FUEL FEED SYSTEM EFFECTIVITY ALL

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28V DC BATT. BUS

L. AFT PRESS. SW.

L. FWD. PRESS. SW.

L. CENTER PRESS. SW.

FIRE HOT BATT. BUS M M DC BOOST PUMP

AUTO LEFT FWD. BOOST PUMP SELECT ON APU ON

LOW PRESS. ENGINE BOOST PUMP

L. FWD. L. AFT L. CNTR.

DC BOOST PUMP RELAY K191

APU ON

APU FUEL VALVE DISAGREE RELAY K192

N

6 sec.

APU FUEL VAL. (C)

FAULT NO PWR. IF DISAGREE OR TRANSIT

1 = CL. P > 3 psi

DC FUEL PUMP ON (M) EICAS COMPUTER

APU BOOST PUMP CONTROL AND OPERATION EICAS DISPLAY

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6.2. Defueling. Defueling and tank to tank fuel transfer operations are performed on the ground only. Two 28V DC permanent magnet motor actuated defuel valves, one in each main tank, connect the engine fuel feed manifold to the fueling manifold allowing defuel or transfer. The defuel valves are controlled by guarded switches at the fueling station. Defuel Valve. The defuel valve is identical to the engine fuel shutoff valve and crossfeed valve. The actuators and valve bodies are the same part number. The adapter and shaft is customized for each installation. A manual override on lever the actuator allows mechanical opening and closing of the valve and also indicates valve position.


Tank-to-tank transfer. Tank-to-tank fuel transfer is the same procedure as pressure defueling. The appropriate boost or override pumps must be operating to provide sufficient pressure to actuate the fueling valve diaphragms. Open the fueling valves for the tank to receive the fuel and turn on the boost or override pumps for the tanks to be defueled. Monitor the quantity gages to determine progress. It is not necessary to connect fueling nozzles, or to turn the adapter cams to the DEFUEL position. Defuel valve position indication. A blue press-to-test light for each defuel valve indicates valve position. The light comes on when the valve is fully open, and remains on until the valve is fully closed.

Pressure defueling. Press-to-test the blue defuel valve lights after the fueling station has been powered. Turn the adapter cams to the DEFUEL position and connect the nozzles. Open the defuel valves. Turn on the appropriate boost or override pumps for the tank(s) to be defueled using the switchlights in the flight compartment. Suction defueling. Suction defueling of the main tanks is the same as pressure defueling of the tanks except the boost pumps are not used. Suction supplied from the defueling vehicle allows fuel flow through the bypass valves and defuel valves to the vehicle. Suction defueling of the center auxiliary tank is not possible. EFFECTIVITY ALL

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DEFUELING SYSTEM EFFECTIVITY ALL

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7. FUEL JETTISON SYSTEM. The fuel jettison system permits the gross weight of the airplane to be decreased quickly so that design limits for wheels, tires and brakes are not exceeded during an emergency landing. Only fuel from the center auxiliary tank is jettisoned. Jettisonable fuel is limited to the center wing tank for system simplicity and pump out safety. Total available fuel for jettison is 12,000 gal (80,400 lbs). Flow rate during jettison operation is approximately 140,000 pounds per hour (2,333 lbs/min).

7.1. General Description. The fuel jettison system has two jettison pumps, two jettison transfer valves, two jettison valves, two manifolds, and two nozzles. The jettison pumps are in the same housing as the center tank override pumps. The jettison pumps and the override pumps are interchangeable. When the jettison system is operating, the override pumps and the jettison pumps send fuel to the jettison transfer valves. Jettison flow is approximately 140,000 lbs. per hour at 14 psi. The jettison transfer valves are between the output of the override and jettison pump assembly and the fueling manifold. A manifold check valve prevents fuel from the main tank boost pumps from entering the fueling manifold when the transfer valve is open. One jettison manifold is connected to each end of the fueling manifold. The jettison valve at the end of each jettison manifold controls fuel flow to the nozzle. The jettison transfer valves and jettison valves are motor actuated valves. The actuator is identical and interchangeable with the actuators of the other motor actuated valves of the fueling system. The valve bodies are not interchangeable with the other valve bodies due to the smaller diameter of the jettison manifold.

EFFECTIVITY ALL

The fuel jettison outlet tube assembly consists of an aluminum tube with a shroud (bond assembly) made of titanium. The assemblies are immediately inboard of the outboard aileron on each wing.

7.2. Fuel Jettison System Operation. Fuel jettison is accomplished in two steps. First turn the fuel jettison rotary selector ON. This turns on both the center override pumps and jettison pumps, initiates a load shed if both bus tie breakers are closed, and opens the transfer valves. Fuel can now be jettisoned by latching in the nozzle switches. Indication. An amber fault light comes on for either low pump output or transfer valve disagreement. The respective VALVE light on the nozzle valve switches come ON for valve transit and disagreement. The EICAS messages L(R) JET XFR VALVE and FUEL JET NOZ appear if the respective valve disagrees with commanded position or if a nozzle valve is open when the aircraft is on the ground.

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FUEL JETTISON SYSTEM AND OPERATION EFFECTIVITY ALL

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8. FUEL QUANTITY INDICATING SYSTEM (FQIS). The FQIS on the 767 aircraft measures the weight of fuel in the fuel tanks. It consists of tank units, compensators, densitometers, a processor unit, flight deck indicators, load select indicators, and a load select control unit. Fuel weight indication appears in the flight compartment and at the fueling station. The FQIS allows fuel shutoff weights to be preset for ground fueling and it automatically terminates fueling when tanks are full. The FQIS has extensive BITE for fault isolation.

Compensators. There are three compensators, one in each tank. The compensators send a reference signal to the processor to compute fuel volume.

8.1. Design Features.

Wiring Harness. There are four wiring harnesses, one in each main tank and two in the center tank. The wiring harnesses are vendor components.

The FQIS is a microprocessor-controlled variable capacitance gaging system. It uses 28V DC power. A densitometer measures fuel density. Fuel volume is measured by tank units and compensators. Fuel weight, volume appears on LCD indicators. Tank unit characterization (weighting) is done by the FQIS software. The FQIS is a modified brickwall system; it has separate electronics and wiring for each tank so a single or multiple failure of one component will not affect the fuel quantity data for more than one tank. Redundant data outputs ensure that one fault does not degrade system performance. The FQIS is energy limited within the fuel tanks for arc suppression. Processor Unit. The processor is located in the main equipment center. It controls all FQIS and fueling operations except overfill. The processor excites and reads the tank units and compensators, excites and reads the densitometers, computes and transmits fuel weight, controls power to the fueling valves and performs BITE operations. Tank Units. There is a total of 37 tank units in the three tanks. They are identical except for length. The processor excites and reads each tank unit independently, and converts the results to fuel volume. EFFECTIVITY ALL

Densitometers. There are three densitometers, one in each tank. They send signals to the processor which computes the fuel density.

Load Select Indicators. The load select indicators are located in the fueling station on the left wing leading edge outboard of the engine. The upper displays indicate fuel quantity by weight. The lower displays indicate the desired weights (load select weight) that cause the FQIS to close the fueling valves for each tank. Load Select Control. The load select control is on the fueling control panel next to the load select indicators. Three thumbwheel switches allow selection of the value to transfer to a load select indicator. Fuel Quantity Indicator. The fuel quantity indicator in the flight compartment is one module with five indicators. There is one indicator for fuel weight in each of the three tanks, one for total fuel weight/ and one for fuel temperature. The indicators are dark-on-light LCD’s so they can be read easily from any angle.

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FUEL Q QUANTITY INDICATING SYSTEM EFFECTIVITY ALL

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B767 - Fuel System

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