Commercial

Airplane

Group

747

Service Bulletin

Number: 747-24A2168 Revision Transmittal Sheet 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

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

Commercial

Airplane

Group

747

Service Bulletin

Number: 747-24A2168 Summary 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

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
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
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
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
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
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
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
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
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
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
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
BOEING SERVICE BULLETIN 747-24A2168

BLANK PAGE

Sep 24/91 747-24A2168

REV 3: Jul 29/93 10
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
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
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
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

REV 1: Sep 5/91 14
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 CONFIGURATION FSSI

671.09

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
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

REV 1: Sep 5/91 16
BOEING SERVICE BULLETIN 747-24A2168

5

INBD

FWD

B

B

VIEW A-A

C

C

EXISTING

BRACKET

BRACKET

NEW BRIDGE

SUPPORT STRUCTURE

ENGINE STRUT FRONT WING

SPAR

MINIMUM

0.29

986054

FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION

Sep 24/91 SHEET 4 OF 10 747-24A2168

REV 3: Jul 29/93 17
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

REV 1: Sep 5/91 18
BOEING SERVICE BULLETIN 747-24A2168

FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION

Sep 24/91 SHEET 6 OF 10 747-24A2168

REV 1: Sep 5/91 19
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

Sep 24/91 SHEET 7 OF 10 747-24A2168

REV 1: Sep 5/91 20
BOEING SERVICE BULLETIN 747-24A2168

(OPTIONAL)

RIVET

(OPTIONAL)

SPACER

(CLAMP NOT SHOWN)

VIEW F-F

(ROTATED 90`CW)

VIEW E-E

(OPTIONAL)

SPACER

CLAMP

F F

C43563

FIGURE 1. POWER FEEDER CABLE SUPPORT BRACKET INSTALLATION

Sep 24/91 SHEET 8 OF 10 747-24A2168

REV 3: Jul 29/93 21
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

Sep 24/91 SHEET 9 OF 10 747-24A2168

REV 3: Jul 29/93 22
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

Sep 24/91 SHEET 10 OF 10 747-24A2168

REV 3: Jul 29/93 23

Commercial

Airplane

Group

747

Service Bulletin

Number: 747-24A2168 Evaluation Form Date: 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

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directly to this address:

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Service Bulletin Engineering

Boeing Commercial Airplane Group

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BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207