# Boeing Alert Service Bulletin 747-24A2168: Revision 3

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- Document: [Boeing Alert Service Bulletin 747-24A2168](https://openairdocs.org/service-documents/boeing/747-24a2168.md)
- Title as filed: U.S. DOT/FAA - Service Bulletin
SB-747-24A2168-03
- Pages: 29
- PDF: https://openairdocs.org/files/sha256/d7/d7/d7d7ebe67974784534a1bce0487c0c317f3fc0d92538ba4322d50d0126596f91
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## Text

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### Page 1

Commercial
Airplane
Group
747
Service Bulletin
Number: 747-24A2168 Revision Transmittal SheetDate: September 24, 1991
Revision 3: July 29, 1993
ATA System: 2451
SUBJECT: ELECTRICAL POWER - INSPECTION OF THE CLEARANCE BETWEEN THE POWER
FEEDER CABLES AND FUEL TUBE, AND MODIFICATION OF THE POWER FEEDER
CABLE SUPPORT BRACKETS
This revision includes all pages of the service bulletin.
COMPLIANCE INFORMATION RELATED TO THIS REVISION
Federal Aviation Administration (FAA) Airworthiness Directive 92-27-13, Amendment 39-8448 is related to
this service bulletin.
No more work is necessary on airplanes changed by Revision 2 of this service bulletin.
SUMMARY
This revision is sent to make these changes:
- Add a step to remove pneumatic duct for access to the installation area and a step to check a clearance
between the bracket and the adjacent pneumatic duct.
- Add installation of optional spacers if required to increase the clearance between power feeder cables and
the bracket.
- Add installation of optional spacers if required to fill the gap between the inboard leg of new bracket and
the existing bracket.
Vertical lines are put on the left edge of each page, except in Paragraph I.A., Effectivity, to show the location
of important changes.
Pages with a revision number and date, but no vertical lines, have no important changes.
REVISION HISTORY
Initial Release: September 24, 1991
Revision 1: December 5, 1991
Revision 2: September 24, 1992
Revision 3: July 29, 1993
BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207

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### Page 3

Commercial
Airplane
Group
747
Service Bulletin
Number: 747-24A2168 SummaryDate: September 24, 1991
Revision 3: July 29, 1993
ATA System: 2451
SUBJECT: ELECTRICAL POWER - INSPECTION OF THE CLEARANCE BETWEEN THE POWER
FEEDER CABLES AND FUEL TUBE, AND MODIFICATION OF THE POWER FEEDER
CABLE SUPPORT BRACKETS
BACKGROUND
This service bulletin is issued to inspect the
clearance between the fuel tube and the power
feeder cables in number 2 and 3 struts, and to install
the power feeder support brackets to separate the
cables from the fuel tube. On one airplane, a hole
developed in number 2 strut fuel tube due to chafing
between the fuel tube and the power feeder cables.
This resulted in a fire in number 2 strut.
ACTION (PRR 82874)
Phase I: Inspect the clearance between the power
feeder cables and the fuel tube in number 2 and 3
struts on Group 1 and 2 airplanes, and in number 3
strut on Group 3 and 4 airplanes.
Phase II: On Group 2, 3, and 4 airplanes, install new
cable support brackets in number 2 and 3 struts.
COMPLIANCE
Federal Aviation Administration (FAA) Airworthiness
Directive 92-27-13, Amendment 39-8448 is related
to this service bulletin.
EFFECTIVITY
Group 1: 747-200 and -300 airplanes line number
679, 681, 685, 688, 701, 702, 703, 711, and 719
Group 2: 747-400 airplanes line number 696
through 734
Group 3: 747-400 airplanes line number 735-843,
845-850, 852-870, 872-875, 877
Group 4: 747-400 airplanes line number 880-884
and 887
MANPOWER
Task
Total
Man-hours
Elapsed Time
(Hours)
Phase I - Inspection 2 1
Phase II -Installation 9 8.5
MATERIAL INFORMATION
Kit Date Available Price
015U0766-1 April 10, 1992 No Charge
Refer to Paragraph I.G., Material - Price and
Availability.
BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207 Summary Page 1 of 2

### Page 4

BOEING SERVICE BULLETIN 747-24A2168
INSTALL NEW CABLE SUPPORT BRACKETS TO
SEPARATE THE POWER FEEDER CABLE FROM
THE FUEL TUBE
PHASE II:
FUEL TUBE
PHASE I:
FSSI
671.09
INSPECT THE CLEARANCE
BETWEEN THE FUEL TUBE
AND THE POWER FEEDER
CABLES
POWER FEEDER
CABLES
FRONT WING
SPAR
FWD
RIGHT SIDE OPPOSITE
LEFT SIDE SHOWN
UP
INBD
985469
Sep 24/91
REV 1: Sep 5/91 Summary Page 2 of 2

### Page 5

Commercial
Airplane
Group
747
Service Bulletin
Number: 747-24A2168
Date: September 24, 1991
Revision 3: July 29, 1993
ATA System: 2451
SUBJECT: ELECTRICAL POWER - INSPECTION OF THE CLEARANCE BETWEEN THE POWER
FEEDER CABLES AND FUEL TUBE, AND MODIFICATION OF THE POWER FEEDER
CABLE SUPPORT BRACKETS
I. PLANNING INFORMATION
A. Effectivity
1. Airplanes
Refer to Service Bulletin Index Document D6-30300, Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
This service bulletin is for only these airplanes:
IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER
AIR CANADA (ACN)
3 RT101-RT103
AIR CHINA (BEJ)
3 RT031-RT033
AIR FRANCE (AFA)
3 RT071 RT121 RT591 RT711-RT712
4 RT072
AIR INDIA (AIN)
1 RS781-RS782
AIR NEW ZEALAND, LTD. (ANZ)
3 RT671-RT672
ALL NIPPON AIRWAYS CO. LTD. (ANA)
3 RT751-RT753 RT776-RT777
ASIANA AIRLINES (AAR)
4 RT131
BRITISH AIRWAYS (BAB)
2 RT471-RT473
3 RT474-RT489
Sep 24/91 747-24A2168
REV 3: Jul 29/93 Page 1 of 23

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BOEING SERVICE BULLETIN 747-24A2168
CANADIAN AIRLINES INTERNATIONAL LTD. (CDI)
3 RT701-RT702
CATHAY PACIFIC AIRWAYS, LTD. (CAT)
2 RT451-RT452
3 RT453-RT459
4 RT460
CHINA AIR LINES, INC. (CHI)
3 RT631-RT633
GOVERNMENT OF JAPAN (JAG)
3 RT681-RT682
JAPAN AIRLINES (JAL)
3 RT641-RT650
KLM ROYAL DUTCH AIRLINES (KLM)
2 RT531-RT532
3 RT001-RT007 RT533
KOREAN AIR LINES, INC. (KAL)
2 RT571
3 RT061 RT572-RT576
LUFTHANSA GERMAN AIRLINES (DLH)
2 RT431-RT432
3 RT041-RT047 RT433-RT438
MALAYSIAN AIRLINES SYSTEM BERHAD (MAS)
3 RT021-RT022 RT741-RT742
NORTHWEST AIRLINES, INC. (NWA)
2 RT401-RT405
3 RT406-RT410
QANTAS AIRWAYS, LTD. (QAN)
2 RT551
3 RT552-RT563
4 RT564
SINGAPORE AIRLINES, LTD (SIA)
2 RT501-RT502
3 RT503-RT512
SOUTH AFRICAN AIRWAYS (SAA)
3 RT781-RT782
S583 (583)
1 RD166-RD167
THAI AIRWAYS INTERNATIONAL, INC. (TII)
1 RS341-RS342
3 RT691-RT693
Sep 24/91 747-24A2168
REV 1: Sep 5/91 2

### Page 7

BOEING SERVICE BULLETIN 747-24A2168
UNITED AIR LINES, INC. (UAL)
2 RT601
3 RT602-RT610
4 RT611-RT612
VARIG AIRLINES (VAR)
1 RS331-RS333
3 RT703
IDENTIFICATION BY VARIABLE NUMBER
GROUP 1
RD166-RD167 RS331-RS333 RS341-RS342 RS781-RS782
GROUP 2
RT401-RT405 RT431-RT432 RT451-RT452 RT471-RT473 RT501-RT502 RT531-RT532
RT551 RT571 RT601
GROUP 3
RT001-RT007 RT021-RT022 RT031-RT033 RT041-RT047 RT061 RT071
RT101-RT103 RT121 RT406-RT410 RT433-RT438 RT453-RT459 RT474-RT489
RT503-RT512 RT533 RT552-RT563 RT572-RT576 RT591 RT602-RT610
RT631-RT633 RT641-RT650 RT671-RT672 RT681-RT682 RT691-RT693 RT701-RT703
RT711-RT712 RT741-RT742 RT751-RT753 RT776-RT777 RT781-RT782
GROUP 4
RT072 RT131 RT460 RT564 RT611-RT612
2. Spares
None
Sep 24/91 747-24A2168
REV 1: Sep 5/91 3

### Page 8

BOEING SERVICE BULLETIN 747-24A2168
B. Reason
This service bulletin is issued to inspect the clearance between the fuel tube and the power feeder
cables in number 2 and 3 struts, and to install the power feeder support brackets to separate the
cables from the fuel tube. On one airplane, a hole developed in number 2 strut fuel tube due to
chafing between the fuel tube and the power feeder cables. This resulted in a fire in number 2 strut.
Revision 1 is sent to formalize the service bulletin that was originally sent telegraphically, to add the
modification that will terminate the clearance inspection, to add two groups of airplanes to the service
bulletin effectivity, and to revise the strut drain inspection in Step G of Section III, Accomplishment
Instructions.
Revision 2 is sent to allow usages of the optional brackets and clarify usages of the support brackets
and the wire support clamps.
Revision 3 is sent to add a step to remove the pneumatic duct for access to the installation area and
a step to check the clearance between the bracket and the adjacent pneumatic duct. Installation of
optional spacers is added if required to increase the clearance between power feeder cables and the
bracket. Installation of optional spacers is added if required to fill the gap between the inboard leg of
new bracket and the existing bracket.
C. Description
Phase I: At the first opportunity where manpower and facilities are available, the clearance between
the power feeder cables and the fuel tube in number 2 and 3 struts is inspected on Group 1 and 2
airplanes, and in number 3 strut on Group 3 airplanes. Within 1000 flight hours, the clearance
between the power feeder cables and the fuel tube in number 3 strut is inspected on Group 4
airplanes.
Phase II: Within 12 months after receipt of Revision 1 of this service bulletin, the cable support
brackets are installed on Group 2, 3, and 4 airplanes to separate the power feeder cables from the
fuel tube.
Airplane effectivity is divided into groups because of the requirement of the inspection and
installation.
Revision 1 - No more work is necessary on Group 1 airplanes changed by the initial release of this
service bulletin and more work is necessary on Group 2 airplanes changed by the initial release of
this service bulletin.
Revision 2 - No more work is necessary on airplanes changed by Revision 1 of this service bulletin.
Revision 3 - No more work is necessary on airplanes changed by Revision 2 of this service bulletin.
The changes in this service bulletin will not change the Central Maintenance Computer System
(CMCS).
NOTE: Evaluation of service bulletin 747-36-2112 is recommended during accomplishment of the
changes specified in this service bulletin.
Sep 24/91 747-24A2168
REV 3: Jul 29/93 4

### Page 9

BOEING SERVICE BULLETIN 747-24A2168
D. Compliance
Federal Aviation Administration (FAA) Airworthiness Directive 92-27-13, Amendment 39-8448, is
related to this service bulletin.
E. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The repairs and
changes specified in this service bulletin comply with the applicable Federal Aviation Regulations
(FAR) and are FAA approved.
The FAA has examined the inspection and repair procedures specified in Revision 2 to Service
Bulletin 747-24A2168, "Electrical Power - Inspection of the Clearance between the Power Feeder
Cables and Fuel Tube, and Modification of the Power Feeder Cable Support Brackets". The FAA has
approved the inspection and repair procedures as an alternative to those specified in Airworthiness
Directive (AD) 92-27-13, Amendment 39-8448.
F. Manpower
The data below shows an estimate of the man-hours necessary to do this inspection and installation
for each airplanes. This estimate is for direct labor only, done by an experienced crew. Adjust the
estimate with operator man-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 examine the work
- Time to cure the materials
- Time to make the parts
- Time to find the tools.
Task Number of Persons Man-Hours Elapsed Time (Hours)
Phase I Inspection 2 2 1
Phase II
Open Access 1 2 2
Change 1 4 4
Test 2 1 0.5
Close Access 1 2 2
TOTAL FOR STRUT 9 8.5
Sep 24/91 747-24A2168
REV 3: Jul 29/93 5

### Page 10

BOEING SERVICE BULLETIN 747-24A2168
G. Material - Price and Availability
Boeing can supply the kit shown in Paragraph II.A., Parts Necessary For Each Airplane, as shown
below. If there is a limit in the quantity of kits, a supply sequence is given by Spares.
Kit Number Name Date Quantity Unit Price
015U0766-1 Kit, Power Feeder Cable
Support Bracket
Installation
April 10, 1992 50 No Charge
May 11, 1992 50 No Charge
June 10, 1992 50 No Charge
July 10, 1992 6 No Charge
Items shown as "No Charge" can change to "Charge" after 180 days from the date shown above.
The kits are subject to the terms and conditions of the Boeing's standard purchase order
acknowledgment. The prices are subject to acceptance within 180 days from the date shown above.
After 180 days, new price data is applicable. Prices are in United States Dollars. Terms: Net 30
days.
Send purchase orders and letters about the supply data to the Director of Spares and refer to this
service bulletin number.
H. Special Tools - Price and Availability
None
I. Weight and Balance
Change in Weight
(Pounds)
Change in Moment
(Pound-Inches)
Phase I None None
Phase II +3.5 +4358
Sep 24/91 747-24A2168
REV 1: Sep 5/91 6

### Page 11

BOEING SERVICE BULLETIN 747-24A2168
J. References
1. Existing Data:
a. 747 or 747-400 Maintenance Manual Subjects 06-09-08, 24-22-00, 28-22-07, 51-20-01,
51-24-00, and 54-10-02 or 54-53-00
b. Overhaul Manual 28-00-10
c. Boeing Standard Wiring Practices Manual 20-10-13
d. Boeing Service Bulletin 747-36-2112, "Pneumatic System - Engine Bleed Air Distribution
System - Leading Edge Duct Change"
e. FAA Airworthiness Directive 92-27-13, Amendment 39-8448
2. Data supplied with this service bulletin:
None
K. Publications Changed
None
L. Electrical Load Data
Not changed
Sep 24/91 747-24A2168
REV 3: Jul 29/93 7

### Page 12

BOEING SERVICE BULLETIN 747-24A2168
II. MATERIAL INFORMATION
A. Parts Necessary For Each Airplane
1. To get the kit shown below, refer to Paragraph I.G., Material - Price and Availability.
NOTE: One top kit is necessary for each airplane in Group 2, 3, and 4 airplanes.
015U0766 - KIT, POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
-1
Quantity Part Number Name
- 015U0766-1 Kit, Power Feeder Cable Support Bracket Installation
1 287U1220-1 (optional
287U1220-31)
Bridge Bracket (Number 2 strut)
1 287U1220-2 (optional
287U1220-32)
Bridge bracket (Number 3 strut)
1 287U1220-23 Support Bracket (Number 3 strut)
1 287U1220-24 Support Bracket (Number 2 strut)
1 287U1220-27 (optional
287U1220-37)
Support Bracket (Number 2 strut)
1 287U1220-28 (optional
287U1220-38)
Support Bracket (Number 3 strut)
8 TA025090-16 Clamp
1 BACC10GU102 Clamp
2 BACC10GU104 Clamp
8 BACB30VT5K2 Bolt
2 BACB30NF4-14 Bolt
2 BACB30NF4-16 Bolt
6 BACB30FP6-4 Bolt
10 NAS1801-3-10 Screw
8 BACR15BB5AD6 Rivet
8 BACC30BL5 Collar
6 BACC30M6 Collar
8 AN960C10 Washer
4 AN960D416 Washer
2 AN960JD10L Washer
Sep 24/91 747-24A2168
REV 1: Sep 5/91 8

### Page 13

BOEING SERVICE BULLETIN 747-24A2168
A. (Continued)
2. Parts and Materials Supplied by the Operator:
Quantity Part Number (Specification) Name
30 Feet Permacel P424 (a) (b) (c) Tape
8 BACS18AF3 (d) Spacer
2 BACR15BA3AD (e) (d) Rivet
4 NAS42DD5 (e) (f) Spacer
4 BACB30VT5K (e) (f) Bolt
(a) Necessary for Phase I only
(b) Scotch 70 or scotch 61 is optional to permacel P424
(c) Permacel Division Johnson and Johnson (V99742)
US Highway Mo 1 P.O. BOX 671
New Brunswick, New Jersey 08903
(d) Optional part. Use to increase clearance between the cables and
outboard edge of the bracket.
(e) Length selected on installation
(f) Optional part. Use to fill gap between the inboard leg of new
bracket and the existing bracket.
B. Parts Necessary to Change Spares
None
C. Special Tools and Equipment
No special tools or equipment are necessary to do the change in this service bulletin. Also,
maintenance and overhaul tools in manuals shown in Paragraph I.J., References, can be necessary.
Examine operator tool supply to make sure all necessary tools are available.
D. Existing Parts Accountability
None
Sep 24/91 747-24A2168
REV 3: Jul 29/93 9

### Page 14

BOEING SERVICE BULLETIN 747-24A2168
BLANK PAGE
Sep 24/91 747-24A2168
REV 3: Jul 29/93 10

### Page 15

BOEING SERVICE BULLETIN 747-24A2168
III. ACCOMPLISHMENT INSTRUCTIONS
NOTES:
1. The paragraphs identified with letters give the general work instructions and the necessary tests.
The instructions identified with numbers on the figure(s) give the recommended sequence of steps.
2. The work instructions are divided into work packages. Man-hours and elapsed time for each
package are given in Paragraph I.F., Manpower. Each work package can be done independently.
3. Unless specified differently, these dimensions and tolerances are used:
- All linear dimensions are in inches
- Tolerance on linear dimensions other than rivet and bolt edge margin is plus or minus 0.03 inch
- Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch
- The hole dimensions for standard solid rivets are found in 747 Structural Repair Manual Chapter
51
- The torque limits to tighten nuts and bolts are found in 747 Structural Repair Manual Chapter 51.
4. Obey all warnings and cautions in the specified manual sections.
PHASE 1- INSPECTION OF THE CLEARANCE BETWEEN THE POWER FEEDER CABLES AND
THE FUEL TUBE
At the first opportunity where manpower and facilities are available, inspect the clearance between the
power feeder cables and the fuel tube in the inboard number 2 and 3 strut on Group 1 and 2 airplanes,
and in number 3 strut only on Group 3 airplanes. Within 1000 flight hours, inspect the clearance between
the power feeder cables and the fuel tube in number 3 strut only on Group 4 airplanes.
A. Remove electrical power from the airplane per the 747 or 747-400 Maintenance Manual Subject
24-22-00.
B. Get access to the power feeder cables and fuel tube in the number 2 or 3 strut area. Use access door
511CT, upper inboard nacelle, to get access to the left inboard number 2 strut. Use access door
611CT, upper inboard nacelle, to get access to the right inboard number 3 strut.
C. Inspect the fuel tube for damage or chafing. If damage or chafing is found, rework the fuel tube as
follows:
1. Hand-blend nicks, scratches, or gouges to form a smooth transition from the damaged area to the
undamaged area. Do not remove metal below the root of the damage.
2. Determine the maximum reduction of wall thickness of the damaged area. If the damage area
exceeds 0.0035 inch, rework the fuel tube per the Overhaul Manual Section 28-00-10, or replace
and test the fuel tube per the 747 or 747-400 Maintenance Manual Subject 28-22-07
3. Dye check damaged area for cracks
4. Refinish in accordance with the original finish requirements.
D. Inspect the power feeder cables for damage or chafing. If damage or chafing is found, repair power
feeder cables as specified in the Boeing Standard Wiring Practices Manual, Chapter 20, Section
20-10-13.
Sep 24/91 747-24A2168
REV 1: Sep 5/91 11

### Page 16

BOEING SERVICE BULLETIN 747-24A2168
E. Determine and establish the clearance between the fuel tube and the power feeder cables (bundle
number W274 at the number 2 strut and W282 at the number 3 strut) as follows:
1. If there is 0.75 inch or more clearance and no sign of damage or chafing to the fuel tube and the
power feeder cables, do the applicable requirement:
- On Group 1 airplanes, no further action is required
- On Group 2, 3 and 4 airplanes, repeat the clearance inspection at intervals not to exceed 1000
flight hours.
2. If there is less than 0.75 inch clearance and no sign of damage or chafing to the fuel tube and the
power feeder cables, relocate the power feeder cables to get as much clearance as possible.
- If 0.75 inch or more clearance is obtained, do the applicable requirement:
- On Group 1 airplanes, no further action is required
- On Group 2, 3, and 4 airplanes, repeat the clearance inspection at intervals not to exceed
1000 flight hours.
- If the obtained clearance is still less than 0.75 inch, apply tape to the fuel tube as described in
Step F and repeat the inspection at intervals not to exceed 500 flight hours.
3. Make sure that there is one inch minimum clearance between the ECS bleed duct and the power
feeder cables.
F. Apply tape to the fuel tube as follows if necessary:
1. Clean the fuel tube per operator's standard procedure. Do not remove primer from the fuel tube
2. Apply tape (permacel P424 or scotch 70) to the fuel tube extending two inches on either side of the
minimum clearance area. Overlap tape one half the width on each wrap. Repeat this step four
times. Reverse the direction of the wrap each time. If scotch 61 tape is used, repeat this step
eight times. Tie the tape at both ends with lacing tape using a clove hitch and a square knot
G. Inspect and if necessary, clean strut drains and sealant as specified in the 747 or 747-400
Maintenance Manual Subject 54-10-02 or 54-53-00.
NOTE: Strut drains should be inspected and cleaned each time any work is done in the strut.
Plugged drains may prevent disposal of accumulated liquids from the strut and affect
operation of the strut.
H. Close the access doors that you opened in Step B.
I. Put the airplane back to the serviceable condition.
Sep 24/91 747-24A2168
REV 1: Sep 5/91 12

### Page 17

BOEING SERVICE BULLETIN 747-24A2168
PHASE II - INSTALL POWER FEEDER SUPPORT BRACKETS TO TERMINATE THE CLEARANCE
INSPECTION
On Group 2, 3, and 4 airplanes, do the following within 12 months after receipt of revision 1 of this
service bulletin.
A. Remove electrical power from the airplane per the 747-400 Maintenance Manual Subject 24-22-00.
B. Get access to the installation areas on the strut number 2 or 3 as follows:
1. Remove access door 511CT, upper inboard nacelle, to get access to the left inboard number 2
strut and access door 611CT, upper inboard nacelle, to get access to the right inboard number 3
strut
2. Remove the pneumatic duct section for access to the bracket installation area as specified in
747-400 Maintenance Manual Subject 36-11-01.
C. Install the cable support brackets on strut 2 and 3 as shown in Figure 1.
D. Install the pneumatic duct section as specified in 747-400 Maintenance Manual Subject 36-11-01.
E. Do a check to make sure that the clearance between the bracket and adjacent pneumatic duct is 0.75
inch or more. If the clearance is less than 0.75 inch, adjust the pneumatic duct as specified in service
bulletin 747-36-2112.
F. Inspect and if necessary, clean strut drains and sealant as specified in the 747-400 Maintenance
Manual Subject 54-53-00.
NOTE: Strut drains should be inspected and cleaned each time any work is done in the strut.
Plugged drains may prevent disposal of accumulated liquids from the strut and affect
operation of the strut.
G. Close the access doors that you removed and opened in Step B.
H. Put the airplane back to the serviceable condition.
Sep 24/91 747-24A2168
REV 3: Jul 29/93 13

### Page 18

BOEING SERVICE BULLETIN 747-24A2168
LEFT SIDE SHOWN
RIGHT SIDE OPPOSITE
1
3
1
2
2
SEE DETAIL I FOR NEW CONFIGURATION
EXISTING CONFIGURATION
671.09
FSSI
WING SPAR
FRONT
UP
INBD
FWD
TUBE
FUEL
985810
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
Sep 24/91 SHEET 1 OF 10 747-24A2168
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### Page 19

BOEING SERVICE BULLETIN 747-24A2168
15
16
WIRE BUNDLE
W4300 (LEFT SIDE)
W4302 (RIGHT SIDE)
WIRE BUNDLE
W212 (LEFT
SIDE ONLY)
12
E
E
13
13
12
INSTALLATION
BRACKET
FOR BRIDGE
DETAIL II
SEE
DETAIL I
NEW CONFIGURATIONFSSI671.09
D
684.18
FSSI
D
12
14
INBD
UP
FWD
986928
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
Sep 24/91 SHEET 2 OF 10 747-24A2168
REV 3: Jul 29/93 15

### Page 20

BOEING SERVICE BULLETIN 747-24A2168
SPAR
FRONT WING
FUEL TUBE
DETAIL II INBD
FWD
4
3.40
4
A
A
FSSI
671.09 5
986728
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
Sep 24/91 SHEET 3 OF 10 747-24A2168
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### Page 21

BOEING SERVICE BULLETIN 747-24A2168
5
INBD
FWD
B
B
VIEW A−A
C
C
EXISTING
BRACKET
BRACKET
NEW BRIDGE
SUPPORT STRUCTURE
ENGINE STRUTFRONT WINGSPAR
MINIMUM
0.29
986054
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
Sep 24/91 SHEET 4 OF 10 747-24A2168
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### Page 22

BOEING SERVICE BULLETIN 747-24A2168
VIEW B−B
SUPPORT BRACKET
FWD
UP
(ROTATED 20° CW)
FRONT WING SPAR
7
6
986696
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
Sep 24/91 SHEET 5 OF 10 747-24A2168
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### Page 23

BOEING SERVICE BULLETIN 747-24A2168
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
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BOEING SERVICE BULLETIN 747-24A2168
(3 PLACES)
EXISTING
STAND−OFF
(4 PLACES)
LOOKING OUTBOARD
TRACE C/L
FRONT SPAR
0.75
9.00
VIEW D−D
11
10
UP
FWD
987701
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
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BOEING SERVICE BULLETIN 747-24A2168
(OPTIONAL)
RIVET
(OPTIONAL)
SPACER
(CLAMP NOT SHOWN)
VIEW F−F
(ROTATED 90°CW)
VIEW E−E
(OPTIONAL)
SPACER
CLAMP
FF
C43563
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
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BOEING SERVICE BULLETIN 747-24A2168
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the
figure.
1 Remove and discard the clamp to release the power feeder cables from the structure.
2 Remove the clamp from the support bracket. Keep the clamp and the hardware.
NOTE: Wire bundle W212 is on the left side only. Wire bundles W4300 (left side) and W4302 (right
side) may not exist on some airplanes.
3 Remove and discard the cable support bracket.
4 Measure the bracket length as shown and do the applicable step:
o If the bracket length is longer than 4.2 inches, cut the bracket to 3.4 inches as shown and refinish
the cut surface as specified in the 747-400 Maintenance Manual Subject 51-24-00.
o If the bracket length is 4.2 inches or less, do not cut the bracket
5 Do these steps:
a. Locate the bridge bracket as shown. Use bridge bracket 287U1220-1 (optional 287U1220-31) for
number 2 strut and bridge bracket 287U1220-2 (optional 287U1220-32) for number 3 strut.
b. Do a check to make sure that clearance between the bracket and the fire extinguisher tube is not
less than 0.20 inch. If the clearance is less than 0.20 inch, trim the flanges of the bracket (2
places) as shown in View A-A as required to obtain the clearance. Refinish the bared surface as
specified in 747-400 Maintenance Manual Subject 51-20-01.
6 Install bolt BACB30NF4-14 and washer AN960D416.
7 Install bolt BACB30NF4-16 and washer AN960D416.
8 Locate and drill the 0.161 to 0.164 inch hole (4 places).
9 Install the bolt BACB30VT5K2 and collar BACC30BL5 (4 places). If there is a gap between the leg of
new bracket and the existing bracket, it is optional to install spacer NAS42DD5 (4 places) of required
length in between brackets to fill the gap. If optional spacers is used, use the bolt BACB30VT5K (4
places) of required length to secure new bracket.
10 Locate and install the support bracket using rivet BACR15BB5D6. Use support bracket 287U1220-24
for number 2 strut and support bracket 287U1220-23 for number 3 strut.
11 Locate and install the support bracket using bolt BACB30FP6-4 and collar BACC30M6. Use support
bracket 287U1220-27 (optional 287U1220-37) for number 2 strut and support bracket 287U1220-28
(287U1220-38) for number 3 strut.
12 Route the power feeder cables as shown and install the clamp TA025090-16 using screw
NAS1801-3-10, and washer AN960C10. To make sure of the clearance of the power feeder cables,
install the clamp to secure the power feeder cables at the bridge bracket first and then pull the slack of
the power feeder cables forward before you install the next clamp.
13 Install the clamp that you kept in Circle Note 2.
14 Install the clamps to secure the wire bundles using screw NAS1801-3-10 and washer AN960JD10L.
Use clamp BACC10GU102 for wire bundle W212 (left side only) and clamp BACC10GU104 for wire
bundles W4300 (left side) and W4302 (right side) if the airplane has the wire bundles.
15 Route the power feeder cables as shown and install the clamp TA025090-16 using screw
NAS1801-3-10, washer AN960C10. It is optional to add spacer BACS18AF3 (four spacers or 0.25 inch
maximum) under the clamp to increase the clearance between the cables and the outboard edge of the
bracket as shown in View E-E. As an option, secure the spacer to the bracket with rivet as follows:
o Use hole in spacer to locate the rivet hole as shown in View F-F
o Do 100 degree countersink hole in top spacer to 0.125 inch diameter
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
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BOEING SERVICE BULLETIN 747-24A2168
o Install rivet BACR15BA3AD of required length.
16 Remove all dirt and debris from the strut compartment using the operator's standard procedure.
FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION
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### Page 29

Commercial
Airplane
Group
747
Service Bulletin
Number: 747-24A2168 Evaluation FormDate: September 24, 1991
Revision 3: July 29, 1993
ATA System: 2451
Prepared By: Tuan Lam
SUBJECT: ELECTRICAL POWER - INSPECTION OF THE CLEARANCE BETWEEN THE POWER
FEEDER CABLES AND FUEL TUBE, AND MODIFICATION OF THE POWER FEEDER
CABLE SUPPORT BRACKETS
Use this evaluation form to tell us what you think of the quality of this service bulletin. We will use the data
that you give us to improve the quality of our service bulletins. Please include data about these or other
items:
- Did this service bulletin meet your estimate of quality?
- How easy is this service bulletin to understand?
- Are the Planning Information, Material Information and Accomplishment Instructions satisfactory?
- Will you do this service bulletin fully? If not, please tell us why.
- Is the Manpower estimate satisfactory?
NOTE: Please do not use this evaluation form to tell us to make changes to your manuals. To make these
changes, please use a Publication Change Request (PCR) form.
Please give us this data:
OPERATOR: TODAY'S DATE:
PREPARED BY: TITLE:
ORGANIZATION: TELEX CODE:
TELEPHONE NUMBER:
COMMENTS:
If you have other comments please use the other side. Thank you for the time you used to complete this
form.
Give the completed evaluation form to your Boeing Field Service Representative or send the evaluation form
directly to this address:
R.G. Kelsey, Manager
Service Bulletin Engineering
Boeing Commercial Airplane Group
P.O. Box 3707, Mail Stop 2L-02
Seattle, WA 98124-2207
BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207

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