# Boeing Special Attention Service Bulletin 757-28-0121: No revision named

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- Document: [Boeing Special Attention Service Bulletin 757-28-0121](https://openairdocs.org/service-documents/boeing/sb-757-28-0121.md)
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- Pages: 20
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## Text

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### Page 1

Commercial 
Airplanes
757
Service Bulletin
SPECIAL ATTENTION
Number: 757-28-0121
Original Issue: August 18, 2010
ATA System: 2841
SUBJECT: FUEL-Fuel Quantity Indicating System (FQIS)- Fuel Quantity Processor Unit, Low Fuel
Quantity Indication Test
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 730-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET
Copyright © 2010 The Boeing Company
Unpublished Work - All Rights Reserved
Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable
subject matter. Boeing also claims copyright in this document as a compilation and/or collective work.
This document includes proprietary information owned by The Boeing Company and/or one or more third parties.
Treatment of the document and the information it contains is governed by contract with Boeing. For more
information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
BBJ, DC-8, DC-9, DC-10, KC-10, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the
Boeing livery are all trademarks owned by The Boeing Company; and no trademark license is granted in
connection with this document unless provided in writing by Boeing.
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Table of Contents
Summary ...................................................... 5
1. PLANNING INFORMATION ........................................ 9
A. Effectivity ................................................ 9
1. Airplanes ............................................. 9
2. Spares Affected ........................................ 1 3
B. Concurrent Requirements ...................................... 1 3
C. Reason ................................................ 1 3
D. Description .............................................. 1 3
E. Compliance .............................................. 1 4
F. Approval ............................................... 1 4
G. Manpower .............................................. 1 4
H. Weight and Balance Changes .................................... 1 4
I. Electrical Load Data ......................................... 1 4
J. References .............................................. 1 5
1. Existing Data .......................................... 1 5
2. Data supplied with this Service Bulletin ............................ 1 5
3. Installation Drawings Used in the Preparation of this Service Bulletin ............ 1 5
K. Publications Affected ........................................ 1 5
L. Interchangeability and Intermixability of Parts ........................... 1 5
2. MATERIAL INFORMATION ........................................ 1 7
A. Material - Price and Availability ................................... 1 7
B. Industry Support Information .................................... 1 7
C. Parts Necessary For Each Airplane ................................. 1 7
1. Kits/Parts ............................................ 1 7
2. Parts and Materials Supplied by the Operator ........................ 1 7
3. Parts Modified and Reidentified ................................ 1 7
4. Parts Removed and Not Replaced .............................. 1 7
D. Parts Necessary to Change Spares ................................. 1 7
E. Special Tooling - Price and Availability ............................... 1 7
F. Special Tooling Necessary to do this Service Bulletin ....................... 1 7
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 1 9
A. GENERAL INFORMATION ..................................... 1 9
B. WORK INSTRUCTIONS ....................................... 1 9
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Commercial 
Airplanes
757
Service Bulletin
SPECIAL ATTENTION
SummaryNumber: 757-28-0121Original Issue: August 18, 2010
ATA System: 2841
SUBJECT: FUEL-Fuel Quantity Indicating System (FQIS)- Fuel Quantity Processor Unit, Low Fuel
Quantity Indication Test
BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.
CONCURRENT REQUIREMENTS
None.
BACKGROUND
This service bulletin provides test procedures to make sure that the Engine Indication and Crew Alerting System
(EICAS) receives both, the LOW FUEL and the FUEL CONFIG discrete signals from the Fuel Quantity Processor
Unit (FQPU), and the Fuel Quantity Indicating System (FQIS), is functioning correctly. If this service bulletin is
not incorporated flight crews may be unaware of low fuel situations that can lead to fuel exhaustion and extreme
emergency measures.
A 757-200 operator reported that the Low Fuel Indicating System failed to alert the flight crew that the fuel in
Left Hand (LH) and Right Hand (RH) main tanks were depleted below the minimum 2,200 lbs in either tank. The
Low Fuel Threshold is 2,200 lbs of fuel for either Main Fuel Tank. When the fuel in either LH or RH main tank
is below 2,200 lbs, the EICAS should receive both the LOW FUEL and FUEL CONFIG discrete signals from the
FQPU in order for EICAS to display the LOW FUEL caution message.
The Operator reported to Boeing that the airplane arrived at it’s destination with main tank fuel levels below the
Low Fuel Threshold. The next flight crew reported 8,000 lbs of fuel in the Center Wing Tank (CWT), 1,800 lbs
of fuel in the Right Hand Main Fuel Tank and 1,400 lbs of fuel in the Left Hand Main Fuel tank.
Boeing determined this to be a safety issue. Operators can expect to eliminate similar safety incidents by doing
the interval tests in accordance with this service bulletin.
757/767-SRP-28-0124 is related to this service bulletin.
ACTION
Test the Low Fuel Quantity Indicating System to make sure that the, Low Fuel Indication, and the Fuel
Configuration indication are functioning correctly.
Make sure the EICAS displays the "LOW FUEL" caution message and the "FUEL CONFIG" light on the Pilots
Overhead Panel (P5 Panel) comes "ON".
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If the test fails troubleshoot for wiring faults, bent connector pins, or damaged equipment. Repair or replace
damaged wires or equipment.
EFFECTIVITY
757-200/-200CB/-200PF/-300 Airplanes line numbers 1 through 1050. Refer to Paragraph 1.A.1., Airplanes, for
the list of affected airplanes.
COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service
bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin
mandatory.
Boeing recommends that the Inspection/Interval Test given in this service bulletin be done every 100 flight hours.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the Inspection/Interval Test given in this service bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
None.
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BOEING SERVICE BULLETIN 757-28-0121
BREAKERS P11-3  EICAS CIRCUIT  CONFIGURATION  FUEL QUANTITY  LIGHT P5  EICAS CIRCUIT
BREAKERS P11-4
FUEL QUANTITY
INDICATION MODULE
(FQIM) P5.  EICAS UPPER
DISPLAY
CENTER
INSTRUMENT
PANEL P1  MISC TEST PANEL
(M10398)
P61 PANEL
EICAS MAINTENANCE
PANEL (M10372)
EICAS LOWER
DISPLAY
P9 CONTROL STAND EICAS
STATUS DISPLAY SWITCH
FLIGHT COMPARTMENT
FQPU
MAIN EQUIPMENT CENTER
DO THE LOW FUEL QUANTITY WARNING TEST TO MAKE  1915952
SURE EICAS AND THE FQPU FUNCTION CORRECTLY.
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Commercial 
Airplanes
757
Service Bulletin
SPECIAL ATTENTION
Number: 757-28-0121
Original Issue: August 18, 2010
ATA System: 2841
SUBJECT: FUEL-Fuel Quantity Indicating System (FQIS)- Fuel Quantity Processor Unit, Low Fuel
Quantity Indication Test
BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
This service bulletin is for the airplanes shown below.
Refer to Service Bulletin Index Document D624N001 Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
DESCRIPTIONCONFIGURATIONGROUP
757-200/-200CB/-200PF/-300 Airplanes line numbers 1 to 1050.-1
Airplane Models:
757-200, 757-200CB, 757-200PF, 757-300
GroupVariable Number
1NA001 - NA028
1NA191 - NA199
1NA201 - NA239
1NA301 - NA305
1NA341 - NA352
1NA391 - NA399
1NA401 - NA408
1NA441 - NA447
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GroupVariable Number
1NA501 - NA586
1NB001 - NB004
1NB021 - NB023
1NB036 - NB041
1NB051 - NB053
1NB061 - NB073
1NB079
1NB131 - NB148
1NB161 - NB162
1NB166 - NB168
1NB201 - NB204
1NB221 - NB228
1NB230
1NB236
1NB239
1NB261 - NB267
1NB291 - NB299
1NB301 - NB302
1NB311 - NB312
1NB321 - NB331
1NB421 - NB438
1NB446
1NB451 - NB454
1NB501 - NB523
1NB561
1NB571
1NB581 - NB583
1NC001 - NC033
1NC041 - NC042
1NC051 - NC052
1NC056 - NC062
1NC066 - NC084
1NC091 - NC094
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GroupVariable Number
1NC151
1NC161
1NC901 - NC951
1NC971 - NC974
1ND001 - ND007
1ND011 - ND059
1ND111 - ND113
1ND161 - ND199
1ND201 - ND203
1ND221 - ND225
1ND241 - ND248
1ND301 - ND322
1ND401
1ND891
1ND895
1NE001 - NE008
1NE011 - NE088
1NE091 - NE094
1NE141 - NE150
1NE161 - NE177
1NE201 - NE204
1NE301 - NE302
1NE311 - NE325
1NJ001 - NJ004
1NJ031 - NJ032
1NJ551 - NJ555
1NL001 - NL002
1NL006 - NL017
1NL101 - NL109
1NL141
1NL601 - NL616
1NN001 - NN002
1NN051 - NN052
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GroupVariable Number
1NP901 - NP904
1NS601 - NS616
1NT001 - NT009
1NT201 - NT202
1NT231 - NT234
1NT237 - NT240
1NT242
1NT245 - NT248
1NT281 - NT289
1NT341 - NT347
1NT351 - NT360
1NT371 - NT373
1NT375 - NT379
1NT381 - NT386
1NT401 - NT409
1NT411 - NT412
1NT426 - NT427
1NT431 - NT432
1NT436 - NT438
1NT441 - NT442
1NT446
1NT701 - NT769
1NT791 - NT796
1NT861 - NT862
1NT881 - NT885
1NT901 - NT916
1NT971 - NT985
1NU031 - NU038
1NU701 - NU705
1NU721 - NU728
1NU731 - NU732
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2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
This service bulletin provides test procedures to make sure that the Engine Indication and Crew Alerting
System (EICAS) receives both, the LOW FUEL and the FUEL CONFIG discrete signals from the Fuel
Quantity Processor Unit (FQPU), and the Fuel Quantity Indicating System (FQIS), is functioning correctly.
If this service bulletin is not incorporated flight crews may be unaware of low fuel situations that can
lead to fuel exhaustion and extreme emergency measures.
A 757-200 operator reported that the Low Fuel Indicating System failed to alert the flight crew that the
fuel in Left Hand (LH) and Right Hand (RH) main tanks were depleted below the minimum 2,200 lbs
in either tank. The Low Fuel Threshold is 2,200 lbs of fuel for either Main Fuel Tank. When the fuel in
either LH or RH main tank is below 2,200 lbs, the EICAS should receive both the LOW FUEL and FUEL
CONFIG discrete signals from the FQPU in order for EICAS to display the LOW FUEL caution message.
The Operator reported to Boeing that the airplane arrived at it’s destination with main tank fuel levels
below the Low Fuel Threshold. The next flight crew reported 8,000 lbs of fuel in the Center Wing Tank
(CWT), 1,800 lbs of fuel in the Right Hand Main Fuel Tank and 1,400 lbs of fuel in the Left Hand Main
Fuel tank.
Boeing determined this to be a safety issue. Operators can expect to eliminate similar safety incidents
by doing the interval tests in accordance with this service bulletin.
757/767-SRP-28-0124 is related to this service bulletin.
D. Description
Test the Low Fuel Quantity Indicating System to make sure that the, Low Fuel Indication, and the Fuel
Configuration indication are functioning correctly.
Make sure the EICAS displays the "LOW FUEL" caution message and the "FUEL CONFIG" light on
the Pilots Overhead Panel (P5 Panel) comes "ON".
If the test fails troubleshoot for wiring faults, bent connector pins, or damaged equipment. Repair or
replace damaged wires or equipment.
The work in this service bulletin is done in the maintenance zone(s) given below.
Affected Maintenance Zones
ZoneModel
119, 121, 122, 211, 212, 221, 222757-200, 757-200CB, 757-
200PF, 757-300
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E. Compliance
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to
this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this
service bulletin mandatory.
Boeing recommends that the inspection/Interval Test given in this service bulletin be done every 100
flight hours.
F. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified
in this service bulletin comply with the applicable regulations and are FAA approved, as well as European
Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on
the airplane in its original Boeing delivery configuration or as modified by other approved Boeing
changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
G. Manpower
The table below shows an estimate of the task hours necessary to do this for each . This estimate is
for direct labor only, done by an experienced crew. Adjust the estimate with operator task hour data if
necessary. The estimate does not include lost time. These are some examples of lost time:
 Time to adjust to the workplace
 Time to schedule the work
 Time to inspect the work
 Time to cure the materials
 Time to make the parts
 Time to find the tools.
Elapsed HoursTask HoursNumber of PersonsTask
0.250.251Open Access
0.500.501Test
0.250.251Close Access
1.001.00TOTAL FOR EACH AIRPLANE
H. Weight and Balance Changes
None.
I. Electrical Load Data
Not changed.
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J. References
1. Existing Data
a. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19
b. 757 Aircraft Maintenance Manual (AMM) 24-22-00
c. 757 Fault Isolation Manual (FIM) 28-41-00
d. 757 Wiring Diagram Manual (WDM) 28-41-13
2. Data supplied with this Service Bulletin
None.
3. Installation Drawings Used in the Preparation of this Service Bulletin
K. Publications Affected
1. Publications:
None.
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.
L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
None.
B. Industry Support Information
Boeing warranty remedies are not available for the Inspection/Interval Test given in this service bulletin.
C. Parts Necessary For Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
None.
3. Parts Modified and Reidentified
None.
4. Parts Removed and Not Replaced
None.
D. Parts Necessary to Change Spares
None.
E. Special Tooling - Price and Availability
None.
F. Special Tooling Necessary to do this Service Bulletin
No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance
and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator tool supply to make sure all necessary tools are available.
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3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL
PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,
METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE
DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR
OTHER ELECTRICAL DAMAGE.
NOTE: 1. The instructions identified in Paragraph 3.B., Work Instructions, and the Figure(s)
give the recommended sequence of steps. The sequence of steps to do this service
bulletin can be changed.
2. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
3. Obey all of the warnings and cautions given in the specified manual sections.
4. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures,
and SWPM 20-10-19 for the wire separation requirements, as accepted procedures.
5. A Detailed Inspection is defined as: An intensive examination of a specific item,
installation, or assembly to detect damage, failure, or irregularity. Available lighting
is normally supplemented with a direct source of good lighting at an intensity deemed
appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be
necessary. Surface cleaning and elaborate procedures may be required.
6. A General Visual Inspection is defined as: A visual examination of an interior or
exterior area, installation or assembly to detect obvious damage, failure or irregularity.
This level of inspection is made from within touching distance unless otherwise
specified. A mirror may be necessary to enhance visual access to all exposed surfaces
in the inspection area. This level of inspection is made under normally available
lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may
require removal or opening of access panels or doors. Stands, ladders or platforms
may be required to gain proximity to the area being checked.
7. These work instructions refer to procedures included in other Boeing documents.
When the words "refer to" are used and the operator has an accepted alternative
procedure, the accepted alternative procedure can be used. When the words "in
accordance with" are included in the instruction, the procedure in the Boeing document
must be used.
B. WORK INSTRUCTIONS
1. Supply electrical power. Refer to 757 AMM 24-22-00 as an accepted procedure.
2. Make sure the following six EICAS circuit breakers are closed.
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EICAS CIRCUIT BREAKERS, P11 PANEL
LOCATIONPANELNAMECIRCUIT
BREAKER
J2P11-3EICAS CMPTR LC4078
J29P11-4EICAS CMPTR RC4079
J32P11-4EICAS PILOTS DSPC4094
J31P11-4EICAS DISPLAY SWC4189
J30P11-4EICAS LOWER INDC4082
J3P11-3EICAS UPPER INDC4081
3. Push the MASTER CAUTION Cancel button on the P1-3, Captain Instrument Panel, Center to
reset warnings.
4. Push and release the FUEL QTY test switch on the Miscellaneous Test Panel (M10398), P61
Panel, to the FUEL QTY position.
a. Make sure the FUEL CONFIG light on the P5, Pilot's Overhead Panel, comes on.
b. Make sure the EICAS caution message, LOW FUEL, shows on the upper (EICAS) display,
P1 Panel.
NOTE: If the test fails, trouble shoot for wire faults, bent connector pins, or damaged
equipment. Repair and or replace damaged wires and or equipment. Refer to Fault
Isolation Manual 757 FIM 28-41-00 as an accepted procedure and to Wire Diagram
Manual 757 WDM 28-41-13 for related wires.
5. Put the airplane back to a serviceable condition.
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