Commercial 

Airplanes 747

Service Bulletin

ALERT

Number: 747-53A2371

Original Issue: July 29, 1993

Revision 2: December 11, 2012

ATA System: 5300

SUBJECT: FUSELAGE - Center Section - STA 780 to STA 940 Upper Deck Tension Tie Inspection,

Repair, and Modification

Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15

CFR 300-774). 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.

ECCN: 9E991

BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET

Copyright © 1993 Boeing.

Unpublished Work. All Rights Reserved.

Treatment of this document and its content is governed by contract with Boeing. Rights to use this document

are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The

Boeing Company.

Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, DreamlinerTM,

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 Boeing

liveries 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. BOEING is a trademark of Boeing Management

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4.0
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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT

BLANK PAGE
Table of Contents

Revision Transmittal Sheet ............................................ 5

Summary ...................................................... 7

1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 23

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 25

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 26

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

FIGURE 1: THIS FIGURE IS DELETED (REVISION 2) . . . . . . . . . . . . . . . . . . . . . . . . . . 31

FIGURE 2: TENSION TIE DETAILED INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

FIGURE 3: REPAIR OR MODIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

FIGURE 4: THIS FIGURE IS DELETED (REVISION 2) . . . . . . . . . . . . . . . . . . . . . . . . . . 48

FIGURE 5: THIS FIGURE IS DELETED (REVISION 2) . . . . . . . . . . . . . . . . . . . . . . . . . . 49

FIGURE 6: AFTER MODIFICATION INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

FIGURE 7: REPAIR STRAP FABRICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

FIGURE 8: TENSION TIE HIGH FREQUENCY EDDY CURRENT INSPECTION . . . . . . . . . . . . 55

APPENDIX A: FLIGHT SAFETY SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT

BLANK PAGE
Commercial 

Airplanes 747

Service Bulletin

ALERT

Revision Transmittal Sheet Number: 747-53A2371

Original Issue: July 29, 1993

Revision 2: December 11, 2012

ATA System: 5300

SUBJECT: FUSELAGE - Center Section - STA 780 to STA 940 Upper Deck Tension Tie Inspection,

Repair, and Modification

This revision includes all pages of the service bulletin.

COMPLIANCE INFORMATION RELATED TO THIS REVISION

More work is necessary on airplanes changed as given in the original issue or Revision 1 of this of this service

bulletin. If the modification given in this service bulletin has not previously been done on all affected tension ties,

then Boeing recommends that the modification be done at the time given in Paragraph 1.E., Compliance. In

addition, Boeing also recommends that operators do a surface high frequency eddy current (HFEC) inspection

of the unmodified aft tension tie channels during the next inspection that is scheduled to be done as given in

this service bulletin.

Federal Aviation Administration (FAA) Airworthiness Directive AD 94-13-06 is related to this service bulletin.

REASON FOR REVISION

This revision is sent to recommend that operators accomplish the modification given in this service bulletin.

These sections were changed:

1. In the Summary: Added new Background information related to the revision. Updated Action section

to reflect new requirements. Added industry support information. Revised Summary illustration text to

reflect changed actions.

2. In paragraph 1.C., Reason: Added new background information related to the revision.

3. In paragraph 1.D., Description: Updated the action descriptions to reflect new requirements, added

"More work" statement, and added affected maintenance zones.

4. In paragraph 1.E., Compliance: Added compliance Tables 1, 2, and 3. In previous revisions of this

service bulletin, compliance information was given in Figure 1 and Figure 5.

5. In paragraph 1.F., Approval: Updated standard approval paragraphs and added alternative method of

compliance statement for AD 94-13-06.

6. In paragraph 1.J., References: Added new references related to this revision.

7. In paragraph 1.K., Publications Affected: Added statement for damage tolerance inspections.

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8. In paragraph 2.B., Added Industry Support Information.

9. In paragraph 3.A., General Information: Updated general notes to current requirements.

10. In paragraph 3.B., Work Instructions, PART 1 - Tension Tie Inspection: Added reference to paragraph

1.E. for compliance information. Deleted the option to defer repair of cracked tension tie aft channels

if additional eddy current inspections find that parts are crack free in other areas.

11. In paragraph 3.B., Work Instructions, PART 2 - After Modification Inspection Program: Added reference

to paragraph 1.E. for compliance information.

12. In paragraph 3.B., Work Instructions, PART 4 and PART 5: These new sections have been added.

13. Figure 1: This figure (logic diagram) has been deleted. Compliance information is now found in the

compliance tables of paragraph 1.E., Compliance.

14. Figure 3: Added example fastener symbol illustration.

15. Figure 4: This figure has been deleted. In previous revisions of this service bulletin, Figure 4 was an

inspection needed to defer repair of cracked tension tie aft channels. The option to defer repair of

cracked tension ties is no longer allowed.

16. Figure 5: This figure (logic diagram) has been deleted. Compliance information is now found in the

compliance tables of paragraph 1.E., Compliance.

17. Figure 8: This new figure is added for high frequency eddy current inspection.

18. Appendix A: This appendix has been updated to reflect revised compliance information.

Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location

of important changes.

Pages with no vertical lines have no important changes.

REVISION HISTORY

Original Issue: July 29, 1993

Revision 1: April 27, 1995

Revision 2: December 11, 2012

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT
Commercial 

Airplanes 747

Service Bulletin

ALERT

Summary Number: 747-53A2371

Original Issue: July 29, 1993

Revision 2: December 11, 2012

ATA System: 5300

SUBJECT: FUSELAGE - Center Section - STA 780 to STA 940 Upper Deck Tension Tie Inspection,

Repair, and Modification

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

This service bulletin gives instructions to do inspections, repairs, and modifications to upper deck tension ties.

The affected tension ties are installed from STA 780 to STA 940 aft of the upper deck floor beams. The failure

of more than one tension tie can result in rapid depressurization of the airplane.

Six operators have reported 47 tension tie cracks on 13 airplanes. Forty-six of the cracks were in the aft channel

of the tension tie. Only one crack was in the forward channel of the tension tie. Cracks usually occur in the upper

flange of the aft channel of the tension tie. These fatigue cracks occur because the tension ties bend under

cabin pressurization loads.

Boeing Service Bulletin 747-53-2088 gives instructions to change the STA 760 tension tie on passenger airplanes.

That service bulletin also gives instructions to change the STA 780 tension tie on 747-200F airplanes.

At line number 204, the tension tie configuration was changed in production.

A structural reassessment of the 747 airplane was conducted under the requirements of Federal Aviation

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as

amended in 1978, to ensure safe operation of 747 airplanes throughout their operational life. From this

requirement, the tension ties from STA 780 to 940 were determined to be significant, in that they are critical to

airplane structural integrity. The failure of more than one tension tie can result in rapid depressurization of the

airplane. Therefore, a flight safety inspection program which will continue throughout the operational life of the

airplane is described in this service bulletin.

Subsequent to the release of Revision 1 of this service bulletin, the upper deck tension ties have been determined

to be structure that could develop Widespread Fatigue Damage (WFD). Due to the concern of WFD in the tension

tie structure, Boeing now recommends that operators accomplish the modification given in this service bulletin.

Previously, the modification was optional unless a crack was found during an inspection.

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For more information about WFD, refer to Boeing Service Letter 747-SL-53-088.

Boeing Service Related Problem (SRP) 747-SRP-53-0403 is related to this service bulletin.

This table is provided to operators for planning purposes only. Refer to the applicable sections for more

information.

Planning Data Affected Reference

Spares Affected No Paragraph 1.A.2., Spares Affected

Paragraph 1.E., Compliance and Paragraph

1.F., Approval

AD Related Yes

Weight and Balance Change Yes Paragraph 1.H., Weight and Balance Changes

Electrical Load Changed No Paragraph 1.I., Electrical Load Data

Publications Affected No Paragraph 1.K., Publications Affected

Airplane Flight Operations Affected (Flight Crew No Paragraph 1.K., Publications Affected

Operations Manual and/or FAA Approved Airplane Flight Manual)

Boeing supplied Kits/Parts Required No Paragraph 2.C.1., Kits/Parts

Paragraph 2.C.2., Parts and Materials Supplied

by the Operator

Operator Supplied Material Yes

Paragraph 2.F., Special Tooling Necessary to

do this Service Bulletin

Special Tooling Required No

ACTION (PRR 85901-120RS)

Do detailed and surface high frequency eddy current (HFEC) inspections for cracks in the outboard ends of

each affected tension tie. If cracks are found, repair before any more flights. At tension tie locations where no

cracks are found, repeat the inspections until the tension tie is repaired or modified. At tension tie locations that

have been repaired or modified, do detailed inspections as given in the After Modification Inspection Program.

If cracks are found in a repaired or modified tension tie, contact Boeing for repair instructions.

This service bulletin contains a flight safety inspection program. The flight safety inspection program is the

minimum inspection program to maintain the structural integrity of the affected area of the airplane. An optional

economics based inspection, to be done earlier than the flight safety inspection, would usually be included in

this type of service bulletin. However, for this area there is no economics based inspection program. The repair

necessary when a crack is found in the flight safety inspection is the same as the repair necessary if a crack is

found earlier.

EFFECTIVITY

747-100/-200B/-200F airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes.

COMPLIANCE

Refer to Paragraph 1.E., Compliance.

Federal Aviation Administration (FAA) Airworthiness Directive AD 94-13-06 is related to this service bulletin.

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT
INDUSTRY SUPPORT INFORMATION

This service bulletin was first released before October of 1994. Thus industry support for affected airplanes

depends upon whether you ever filed a warranty claim with Boeing on this service bulletin.

MANPOWER

Airplanes Total Task Hours Elapsed Hours

Group 1 and 2 113.5 30.5

Group 3 and 7 101.25 27.25

Group 4 89 24

Group 5 and 6 77 21

MATERIAL INFORMATION

Operator Supplied Parts/Materials.

Refer to Paragraph 2.C., Parts Necessary for Each Airplane.

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT

BLANK PAGE
Commercial 

Airplanes 747

Service Bulletin

ALERT

Number: 747-53A2371

Original Issue: July 29, 1993

Revision 2: December 11, 2012

ATA System: 5300

SUBJECT: FUSELAGE - Center Section - STA 780 to STA 940 Upper Deck Tension Tie Inspection,

Repair, and Modification

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

This service bulletin is for the airplane(s) shown below. Refer to PRR 85901-120RS for data about

this change.

Refer to Service Bulletin Index D6-30300 Part 3 for Airplane Variable Number, Line Number, and

Serial Number data.

NOTE: Group 2 airplanes changed as given in Boeing Service Bulletin 747-25-2692,

"Equipment/Furnishings - Upper Deck Passenger Compartment Conversion - Upper Deck

Extension Station 710 - Station 780 Modification," should be considered Group 3 airplanes

for the purposes of this service bulletin.

GROUP CONFIGURATION DESCRIPTION

747 airplanes prior to line number 204 with affected tension ties

installed from STA 780 to 940. The fasteners used to attach the STA

940 tension tie on Group 1 airplanes is different than on Group 2

airplanes.

1 -

747 airplanes prior to line number 204 with affected tension ties

installed from STA 780 to 940. The fasteners used to attach the STA

940 tension tie on Group 2 airplanes is different than on Group 1

airplanes.

2 -

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GROUP CONFIGURATION DESCRIPTION

747 airplanes prior to line number 204, except Group 7 airplanes,

with affected tension ties installed only from STA 800 to 940. There

is no tension tie at STA 780.

3 -

747 airplanes prior to line number 204 with affected tension ties

installed only from STA 820 to 940. The tension ties at STA 780 and

800 were removed during a modification at Boeing.

4 -

747 airplanes prior to line number 204 with affected tension ties

installed only from STA 840 to 940. The tension ties at STA 780, 800,

and 820 were removed during a modification at Boeing. The fasteners

used to attach the STA 940 tension tie on Group 5 airplanes is

different than on Group 6 airplanes.

5 -

747 airplanes prior to line number 204 with affected tension ties

installed only from STA 840 to 940. The tension ties at STA 780, 800,

and 820 were removed during a modification at Boeing. The fasteners

used to attach the STA 940 tension tie on Group 6 airplanes is

different than on Group 5 airplanes.

6 -

747 airplanes prior to line number 204, except Group 3 airplanes,

with affected tension ties installed only from STA 800 to STA 940.

On 747-200F airplane line number 168, Service Bulletin 747-53-2088

gives instructions to change the STA 780 tension tie. On all other

Group 7 airplanes, there is no tension tie at STA 780.

7 -

Airplane Models:

747-100, 747-200B, 747-200F

Variable Number Group

RA001 - RA034 1

RA101 - RA115 1

RA161 - RA162 1

RA163 - RA164 2

RA201 - RA203 1

RA216 1

RA217 2

RA245 - RA246 4

RA251 - RA255 1

RA256 - RA261 2

RA301 - RA306 5

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT
Variable Number Group

RA307 - RA308 6

RA309 2

RA310 6

RA311 2

RA312 6

RA351 - RA360 1

RA369 - RA371 1

RA372 - RA373 2

RA401 - RA412 1

RA413 2

RA414 3

RA501 - RA502 1

RA521 - RA523 1

RA524 - RA527 2

RA532 - RA534 1

RA535 - RA540 2

RA551 - RA552 1

RA559 1

RA560 7

RA561 2

RA581 - RA582 1

RA585 2

RA601 - RA602 1

RA631 - RA633 1

RA634 - RA635 2

RA651 - RA652 1

RA671 - RA674 5

RA675 6

RA676 2

RA677 6

RA701 1

RA702 2

RA721 1

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT
Variable Number Group

RA722 7

RA723 - RA724 3

RA741 1

RA742 - RA743 7

RA761 - RA762 1

RA781 1

RA782 3

RA901 - RA916 1

RB001 - RB005 3

RB013 3

RB041 - RB044 1

RB071 - RB075 2

RB101 - RB102 1

RD001 - RD002 3

RR201 7

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

This service bulletin gives instructions to do inspections, repairs, and modifications to upper deck

tension ties. The affected tension ties are installed from STA 780 to STA 940 aft of the upper deck floor

beams. The failure of more than one tension tie can result in rapid depressurization of the airplane.

Six operators have reported 47 tension tie cracks on 13 airplanes. Forty-six of the cracks were in the

aft channel of the tension tie. Only one crack was in the forward channel of the tension tie. Cracks

usually occur in the upper flange of the aft channel of the tension tie. These fatigue cracks occur

because the tension ties bend under cabin pressurization loads.

Boeing Service Bulletin 747-53-2088 gives instructions to change the STA 760 tension tie on passenger

airplanes. That service bulletin also gives instructions to change the STA 780 tension tie on 747-200F

airplanes.

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BOEING SERVICE BULLETIN 747-53A2371

ALERT ALERT
A structural reassessment of the 747 airplane was conducted under the requirements of Federal Aviation

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR)

25.571 as amended in 1978, to ensure safe operation of 747 airplanes throughout their operational

life. From this requirement, the tension ties from STA 780 to 940 were determined to be significant, in

that they are critical to airplane structural integrity. The failure of more than one tension tie can result

in rapid depressurization of the airplane. Therefore, a flight safety inspection program which will continue

throughout the operational life of the airplane is described in this service bulletin.

Revision 1 is sent to add references to Federal Aviation Administration (FAA) Airworthiness Directive

94-13-06. Revision 1 is also sent to tell affected operators about airplane group changes. Airplanes

RA560, RA742, RA743, and RA722 were moved from Group 1 to Group 7. Airplanes RA723 and RA724

were moved from Group 2 to Group 3. On these airplanes, the tension tie at Station 780 was removed

as part of a Boeing modification and replaced with a floor beam. Revision 1 is also sent to add notes

that explain the affect of the Boeing Extended Upper Deck conversion on airplane groups. Group 1

airplanes modified by Boeing to the Extended Upper Deck configuration should be considered Group

7 airplanes. Group 2 airplanes modified by Boeing to the Extended Upper Deck configuration should

be considered Group 3 airplanes. Revision 1 is also sent to add references to Boeing Service Bulletin

747-25-2692, "Equipment / Furnishings - Upper Deck Passenger Compartment Conversion - Upper

Deck Extension Station 710 - Station 780 Modification." As part of the change in Service Bulletin

747-25-2692, the tension tie at Station 780 is removed and replaced with a floor beam. Airplanes

changed as given in Service Bulletin 747-25-2692 should be considered Group 3 airplanes. This data

was in Notice of Status Change 747-53-2371 NSC 1.

Subsequent to the release of Revision 1 of this service bulletin, the upper deck tension ties have been

determined to be structure that could develop Widespread Fatigue Damage (WFD). Due to the concern

of WFD in the tension tie structure, Boeing now recommends that operators accomplish the modification

given in this service bulletin. Previously, the modification was optional unless a crack was found during

an inspection.

For more information about WFD, refer to Boeing Service Letter 747-SL-53-088.

Boeing Service Related Problem (SRP) 747-SRP-53-0403 is related to this service bulletin.

Revision 2 is sent to recommend that operators accomplish the modification given in this service bulletin.

D. Description

Do detailed and surface high frequency eddy current (HFEC) inspections for cracks in the outboard

ends of each affected tension tie. If cracks are found, repair before any more flights. At tension tie

locations where no cracks are found, repeat the inspections until the tension tie is repaired or modified.

At tension tie locations that have been repaired or modified, do detailed inspections as given in the

After Modification Inspection Program. If cracks are found in a repaired or modified tension tie, contact

Boeing for repair instructions.

This service bulletin contains a flight safety inspection program. The flight safety inspection program

is the minimum inspection program to maintain the structural integrity of the affected area of the airplane.

An optional economics based inspection, to be done earlier than the flight safety inspection, would

usually be included in this type of service bulletin. However, for this area there is no economics based

inspection program. The repair necessary when a crack is found in the flight safety inspection is the

same as the repair necessary if a crack is found earlier.

At line number 204, the tension tie configuration was changed in production.

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ALERT ALERT
NOTES:

1. Inspection and maintenance alternatives are given in a diagram in Paragraph 3.,

ACCOMPLISHMENT INSTRUCTIONS.

2. It is not necessary to count flight-cycles where the cabin differential pressure was below 2.0 psi.

3. The changes specified in Boeing Service Bulletin 747-53-2088, "Frame To Tension Tie Joint

Modification - Body Station 760 or 780," can be made on affected airplanes before or during the

changes specified in this service bulletin.

4. The change given in Boeing Service Bulletin 747-25-2692, "Equipment/Furnishings - Upper Deck

Passenger Compartment Conversion - Upper Deck Extension Station 710 - Station 780 Modification"

should be done on affected airplanes before or during the change given in this service bulletin.

Service Bulletin 747-25-2692 affects Group 2 airplanes RA526, RA527, RA538, and RA540.

5. If the damaged area is more than the specified limits, repair before any more flights. Contact Boeing

for repair instructions. Give the size and location of the damage. When possible, send sketches

and photographs. If the damage includes corrosion, send data on the length, width, and largest

depth of clean up.

SEND TO: BOEING COMMERCIAL AIRPLANE GROUP ATTENTION: MANAGER, AIRLINE

SUPPORT

Revision 2 - More work is necessary on airplanes changed as given in the original issue or Revision 1

of this of this service bulletin. If the modification given in this service bulletin has not previously been

done on all affected airplanes, then Boeing recommends that the modification be done at the time given

in Paragraph 1.E., Compliance. In addition, Boeing also recommends that operators do a surface high

frequency eddy current (HFEC) inspection of the unmodified aft tension tie channels during the next

inspection that is scheduled to be done as given in this service bulletin.

The work in this service bulletin is done in the maintenance zone(s) given below.

Group 1-3, 5-6:

Affected Maintenance Zones

Model Zone

747-100, 747-200B 243, 244

Group 4:

Affected Maintenance Zones

Model Zone

747-200B 243, 244

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ALERT ALERT
Group 7:

Affected Maintenance Zones

Model Zone

747-100, 747-200B, 747-200F 243, 244

E. Compliance

Federal Aviation Administration (FAA) Airworthiness Directive AD 94-13-06 is related to this service

bulletin.

For each affected tension tie, accomplish the inspections given in Tables 1 and 3 until modification is

accomplished as given in Paragraph 3.B., Work Instructions, PART 5. After modification, accomplish

inspections as given in Table 2.

Table 1: Tension Tie Detailed Inspection - (Tension Ties that have not had repair or modification accomplished in accordance with this service bulletin)

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Before the accu- - -

mulation of

1,000 flight cycles after July

27, 1994.

Do a detailed inspection

for cracks in the tension

ties as given in paragraph

3.B., Work Instructions,

PART 1. (a) (b)

Airplanes not previously inspected as given in this

service bulletin.

Within 3,000 - -

flight cycles

from last inspection as given in

this service bulletin.

Repeat the detailed inspection for cracks in the

tension ties as given in

paragraph 3.B., Work Instructions, PART 1. (a)

(b)

Airplanes previously inspected as given in this

service bulletin.

Repeat the detailed in- - - 3,000 flight cycles.

spection for cracks in the

tension ties as given in

paragraph 3.B., Work Instructions, PART 1. (a)

(b)

No crack found.

Before further - -

flight.

Repair the tension tie aft

channel as given in paragraph 3.B., Work Instructions, PART 1. (a) (c)

Crack found in a tension tie

aft channel.

Before further - -

flight.

Contact Boeing for repair

instructions, and do the

repair. (c)

Crack found in other than

a tension tie aft channel.

(a) Doing a repair or modification as given in this service bulletin terminates the initial and/or repetitive inspection requirements given in this compliance table.

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ALERT ALERT
Table 1: Tension Tie Detailed Inspection - (Tension Ties that have not had repair or modification accomplished in accordance with this service bulletin)

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

(b) For Group 1 and 2 airplanes, do inspections of any unmodified or unrepaired tension ties from STA 780

to 940. For Group 3 and 7 airplanes, do inspections of any unmodified or unrepaired tension ties from

STA 800 to 940. For Group 5 and 6 airplanes, do inspections of any unmodified or unrepaired tension

ties from STA 840 to 940. For Group 4 airplanes, do inspections of any unmodified or unrepaired tension

ties from STA 820 to 940.

(c) Do repeat inspections at locations where no crack was found. Refer to Table 2 for inspection requirements

after repair or modification has been done.

Table 2: Inspection After Repair or Modification

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 10,000 - -

flight cycles after the repair or

modification

was done as

given in this service bulletin.

Do a detailed inspection

for cracks at repaired or

modified tension tie locations as given in paragraph 3.B., Work Instructions, PART 2. (a) (b)

Repair or Modification has

been done as given in this

service bulletin.

Before further - -

flight.

Contact Boeing for repair

instructions, and do the

repair.

Any crack found.

Repeat the detailed in- - - 6,000 flight cycles.

spection for cracks at repaired or modified tension

tie locations as given in

paragraph 3.B., Work Instructions, PART 2. (a)

(b)

No crack found.

(a) Group 1 and 2 airplanes, do inspections from STA 780 to 940. Group 3 and 7 airplanes, do inspections

from STA 800 to 940. Group 5 and 6 airplanes, do inspections from STA 840 to 940. Group 4 airplanes,

do inspections from STA 820 to 940.

(b) Additional tension tie inspection requirements are given in Service Bulletin 747-53A2502.

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ALERT ALERT
Table 3: Tension Tie High Frequency Eddy Current Inspection and Modification (Revision 2 - More Work)

- (Tension Ties that have not had repair or modification accomplished in accordance with this service

bulletin)

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 3,000 -

flight cycles after the Revision

2 date of this

service bulletin.

Concurrent with

the next scheduled detailed inspection as given in paragraph

1.E., Compliance, Table 1.

Do a surface high frequency eddy current (HFEC)

inspection for cracks in

the tension ties as given

in paragraph 3.B., Work

Instructions, PART 4. (a)

(b) (d)

All airplanes.

Repeat the detailed in- - - 3,000 flight cycles.

spection for cracks in the

tension ties as given in

paragraph 3.B., Work Instructions, PART 4. (a)

(b) (d)

No crack found.

Before further - -

flight.

Repair the tension tie aft

channel as given in paragraph 3.B., Work Instructions, PART 4. (c)

Crack found.

Within 2,000 -

flight cycles after the Revision

2 date of this

service bulletin.

Before the accumulation of

16,000 total

flight cycles.

Unless previously accomplished, do the tension tie

modification as given in

Paragraph 3.B., Work Instructions, PART 5.

All airplanes.

(a) Doing a repair or modification as given in this service bulletin terminates the initial and/or repetitive inspection requirements given in this compliance table.

(b) For Group 1 and 2 airplanes, do inspections of any unmodified or unrepaired tension ties from STA 780

to 940. For Group 3 and 7 airplanes, do inspections of any unmodified or unrepaired tension ties from

STA 800 to 940. For Group 5 and 6 airplanes, do inspections of any unmodified or unrepaired tension

ties from STA 840 to 940. For Group 4 airplanes, do inspections of any unmodified or unrepaired tension

ties from STA 820 to 940.

(c) Do repeat inspections at locations where no crack was found. Refer to Table 2 for inspection requirements

after repair or modification has been done.

(d) Additional tension tie inspection requirements are given in Service Bulletin 747-53A2502.

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.

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ALERT ALERT
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.

In addition, the Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the

accomplishment of the inspection, repair, and modification procedures with corresponding compliance

times specified in Service Bulletin 747-53A2371, Revision 2, as an alternative method of compliance

to the inspection, repair, and optional modification procedures with corresponding compliance times

required by paragraphs (a) and (b) of AD 94-13-06. All provisions of AD 94-13-06 that are not specifically

referenced in this paragraph remain fully applicable and must be complied with accordingly.

G. Manpower

The table below shows an estimate of the task hours necessary to do the inspection, repair, or

modification for each airplane. 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.

Table 1: Group 1 and 2 airplanes

Task Number of Persons Task Hours Elapsed Hours

Open Access 2 2.0 1.0

Inspect 1 1.5 1.5

Repair or Modify 4 108.0 27.0

Close Access 2 2.0 1.0

TOTAL FOR EACH AIRPLANE

INSPECTION ONLY 5.5 3.5

INSPECTION AND REPAIR OR MODIFICA- 113.5 30.5

TION

Table 2: Group 3 and 7 airplanes

Task Number of Persons Task Hours Elapsed Hours

Open Access 2 2.0 1.0

Inspect 1 1.25 1.25

Repair or Modify 4 96.0 24.0

Close Access 2 2.0 1.0

TOTAL FOR EACH AIRPLANE

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Table 2: Group 3 and 7 airplanes

Task Number of Persons Task Hours Elapsed Hours

INSPECTION ONLY 5.25 3.25

INSPECTION AND REPAIR OR MODIFICA- 101.25 27.25

TION

Table 3: Group 4 airplanes

Task Number of Persons Task Hours Elapsed Hours

Open Access 2 2.0 1.0

Inspect 1 1.0 1.0

Repair or Modify 4 84.0 21.0

Close Access 2 2.0 1.0

TOTAL FOR EACH AIRPLANE

INSPECTION ONLY 5.0 3.0

INSPECTION AND REPAIR OR MODIFICA- 89.0 24.0

TION

Table 4: Group 5 and 6 airplanes

Task Number of Persons Task Hours Elapsed Hours

Open Access 2 2.0 1.0

Inspect 1 1.0 1.0

Repair or Modify 4 72.0 18.0

Close Access 2 2.0 1.0

TOTAL FOR EACH AIRPLANE

INSPECTION ONLY 5.0 3.0

INSPECTION AND REPAIR OR MODIFICA- 77.0 21.0

TION

H. Weight and Balance Changes

Group 1 and 2:

Change in Moment

(Pound-Inches)

Change in Weight

Airplane (Pounds)

Repair or Modifica- +2.7 (a) +2,322.0 (a)

tion

(a) The weight and balance data is only for airplanes repaired

or modified at all affected locations.

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ALERT ALERT
Group 3 and 7:

Change in Moment

(Pound-Inches)

Change in Weight

Airplane (Pounds)

Repair or Modifica- +2.4 (a) +2,088.0 (a)

tion

(a) The weight and balance data is only for airplanes repaired

or modified at all affected locations.

Group 4:

Change in Moment

(Pound-Inches)

Change in Weight

Airplane (Pounds)

Repair or Modifica- +2.1 (a) +1,848.0 (a)

tion

(a) The weight and balance data is only for airplanes repaired

or modified at all affected locations.

Group 5 and 6:

Change in Moment

(Pound-Inches)

Change in Weight

Airplane (Pounds)

Repair or Modifica- +1.8 (a) +1,602.0 (a)

tion

(a) The weight and balance data is only for airplanes repaired

or modified at all affected locations.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data:

a. Engineering Change Memo PRR 85901-120RS

b. Boeing Service Bulletin 747-25-2692, 747-53-2088, 747-53-2371

c. Boeing Service Letter 747-SL-53-088

d. Boeing Service Related Problem (SRP) 747-SRP-53-0403

e. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 94-13-06

f. Service Bulletin Index D6-30300

g. 747 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00

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ALERT ALERT
h. 747-100/200/300 Aircraft Maintenance Manual (AMM) 25-22-01

i. Supplemental Structural Inspection Document (SSID), Boeing Document D6-35022.

2. Data Supplied with this Service Bulletin:

None.

3. Installation Drawings Used in the Preparation of this Service Bulletin:

Drawing Number Title

Tension Tie Installation - STA 760 to STA 940, STA 1040 to STA

1220

65B09631

65B23200 Structures Instl - Condor (DF) (Modification Dwg)

65B24437 Structures Instl - Upper Deck Galley and Cart Lift, Mod Dwg (BA)

65B24474 Structures Instl - KLM Mod. Dwg.

65B24488 Tension Tie Installation STA 760 - STA 940 - Mod Dwg

691U0105 Tension Tie - STA 780 to STA 940, Aft Channel, Repair

The table above lists applicable drawings used to prepare this service bulletin. The drawings are

not necessary to make the specified changes, and are not supplied with this service bulletin. The

drawings may not be applicable to all airplane configurations or operators.

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 affects FCS. DTI requirements for the structure affected

are contained in Paragraph 1.E., Compliance of this service bulletin.

L. Interchangeability and Intermixability of Parts

Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

M. Software Accomplishment Summary

Not affected.

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ALERT ALERT

BLANK PAGE
2. MATERIAL INFORMATION

A. Material - Price and Availability

None.

B. Industry Support Information

This service bulletin was first released before October of 1994. Thus industry support for affected

airplanes depends upon whether you ever filed a warranty claim with Boeing on this service bulletin.

C. Parts Necessary for Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

The following parts or materials are necessary to do the change in this service bulletin. Parts and

materials in the manuals shown in Paragraph 1.J., References, can also be necessary. Examine

operator part and material supply to make sure all necessary parts and materials are available.

Airplane Group - -

7 6 5 4 3 2 1 - -

Quantity Part Number Name

. . . . . 2 2 A (a) Strap

. . . . 2 2 2 B (a) Strap

2 . . 2 2 2 2 C (a) Strap

2 2 2 2 2 2 2 D (a) Strap

2 2 2 2 2 2 2 E (a) Strap

2 2 2 2 2 2 2 F (a) Strap

2 2 2 2 2 2 2 G (a) Strap

2 2 2 2 2 2 2 H (a) Strap

2 . 2 2 . . 2 I (a) Strap

. 2 . . 2 2 . J (a) Strap

20 10 10 12 20 20 20 BACB30MY6K3X Bolt

80 58 58 70 80 88 88 BACB30MY6K4X Bolt

64 48 48 56 64 72 72 BACB30MY6K4Y Bolt

60 60 58 60 62 68 66 BACB30MY6K5X Bolt

64 42 46 64 60 60 64 BACB30MY6K6X Bolt

54 44 38 38 60 60 54 BACB30MY6K7X Bolt

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ALERT ALERT
18 18 18 18 18 28 28 BACB30MY6K8X Bolt

. . . . . 10 10 BACB30MY6K9X Bolt

32 24 24 28 32 36 36 BACB30MY8K4 Bolt

268 210 206 238 272 302 298 BACC30M6 Collar

32 24 24 28 32 36 36 BACC30M8 Collar

64 48 48 56 64 72 72 BACC30R6 Collar

1 BMS 5-95 (b) Sealant

quart

1

quart

1

quart

1

quart

1

quart

1

quart

1

quart

(a) Make as given in FIGURE 7.

(b) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data.

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 shown in Paragraph 1.J., References, can be necessary. Examine

operator tool supply to make sure all necessary tools are available.

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ALERT ALERT
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. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for

definition of the acronyms.

2. Obey all of the warnings and cautions given in the specified manual sections.

3. Unless shown differently, these dimensions and tolerances are used:

– Linear dimensions are in inches

– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus

or minus 0.03 inch

– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch

– Angular tolerance is plus or minus 2 degrees

– Hole dimensions for standard solid rivets and fasteners are in Structural Repair

Manual (SRM) Chapter 51

– Torque limits to tighten nuts and bolts are in SRM Chapter 51

4. Use the approved fastener and process material substitutions as given in SRM

Chapter 51.

5. If the length of any fastener specified in this service bulletin does not meet installation

standards given in SRM Chapter 51, then a fastener of the same specification, or

an approved substitute, with a length which meets the installation standards given

in SRM Chapter 51 may be used. In addition, washers may be installed for fastener

grip length as given in SRM Chapter 51.

6. There is no economics based inspection program for the area affected by this service

bulletin. The repair necessary when a crack is found in the flight safety inspection is

the same as the repair necessary if a crack is found earlier.

7. Report any STA 780 - 940 tension tie damage. Use the reporting system described

in Appendix A of this service bulletin.

8. 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.

9. Boeing Service Letter 747-SL-51-048, Damage Reporting and Repair Plan/Design

Guidelines, is an acceptable procedure to request information from Boeing for

additional structural repair instructions. The Service Letter describes what information

must be provided to Boeing before a structural repair can be provided.

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ALERT ALERT
10. The instructions in Paragraph 3.B., Work Instructions and the figures can include

operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated

Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing

Index contain data on versions of the tools or test equipment that you can use. It is

permitted to use replaced tools. It is not permitted to use superseded tools.

11. If it is necessary to remove more parts for access, you can remove those parts. If

you can get access without removing identified parts, it is not necessary to remove

all of the identified parts. Jacking and shoring limitations must be observed.

12. Where the work instructions include installation of a kept part, a new or serviceable

part with the same part number can be installed as an alternative to the kept part.

13. 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 "as

given in" are included in the instruction, the procedure in the Boeing document must

be used.

B. WORK INSTRUCTIONS

NOTE: When possible, Boeing recommends accomplishment of PART 4 inspection to be done

concurrently with PART 1 inspection.

PART 1 - TENSION TIE DETAILED INSPECTION

1. Remove the ceiling access panels in the main passenger cabin from STA 780 to 940. Refer to

747-100/200/300 AMM 25-22-01.

2. Do a detailed inspection for cracks in the tension ties as given in FIGURE 2. The table that follows

shows the affected tension tie locations.

Airplane Group Tension Ties Affected

STA

940

STA

920

STA

900

STA

880

STA

860

STA

840

STA

820

STA

800

STA

780

Groups 1 and 2 X X X X X X X X X

Groups 3 and 7 - X X X X X X X X

Group 4 - - X X X X X X X

Groups 5 and 6 - - - X X X X X X

NOTE: An X shows that inspection of the tension tie at that location is necessary.

3. If no cracks are found, continue to PART 3. Do the inspection given in FIGURE 2 again at the time

given in Paragraph 1.E., Compliance.

NOTE: As an alternative, modify all affected tension ties as given in FIGURE 3. Do inspections

of the modified tension ties as given in PART 2.

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ALERT ALERT
4. If cracks are found in the aft channel, repair as given in FIGURE 3 before any more flights. If cracks

are found at other locations, repair before any more flights. Contact Boeing for repair instructions.

Do inspections of the repaired tension ties as given in PART 2.

NOTE: – Continue to do inspections of affected tension ties that have not been repaired or

modified. Do the inspection given in FIGURE 2 again at the time given in Paragraph

1.E., Compliance .

– If the repair given in FIGURE 3 does not completely remove cracks in the aft channel,

contact Boeing for repair instructions and do the repair.

5. Continue to PART 3.

PART 2 - AFTER MODIFICATION INSPECTION PROGRAM

1. Remove the ceiling access panels in the main passenger cabin from STA 780 to 940. Refer to

747-100/200/300 AMM 25-22-01.

2. Do inspections of the repaired or modified tension ties as given in FIGURE 6. The table that follows

shows the affected tension tie locations.

Airplane Group Tension Ties Affected

STA

940

STA

920

STA

900

STA

880

STA

860

STA

840

STA

820

STA

800

STA

780

Groups 1 and 2 X X X X X X X X X

Groups 3 and 7 - X X X X X X X X

Group 4 - - X X X X X X X

Groups 5 and 6 - - - X X X X X X

NOTE: An X shows that inspection of the tension tie at that location is necessary.

3. If no cracks are found, continue to PART 3. Do the inspection given in FIGURE 6 again at the time

given in Paragraph 1.E., Compliance .

4. If cracks are found, contact Boeing for repair instructions and do the repair.

5. Continue to PART 3.

PART 3 - RESTORATION

1. Install the ceiling access panels in the main passenger cabin from STA 780 to STA 940. Refer to

747-100/200/300 AMM 25-22-01.

2. Put the airplane back to a serviceable condition.

PART 4 - TENSION TIE HIGH FREQUENCY EDDY CURRENT INSPECTION

1. Remove the ceiling access panels in the main passenger cabin from STA 780 to 940. Refer to

747-100/200/300 AMM 25-22-01.

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2. Do a surface high frequency eddy current (HFEC) inspection for cracks in the tension ties as given

in FIGURE 8. The table that follows shows the affected tension tie locations.

Airplane Group Tension Ties Affected

STA

940

STA

920

STA

900

STA

880

STA

860

STA

840

STA

820

STA

800

STA

780

Groups 1 and 2 X X X X X X X X X

Groups 3 and 7 - X X X X X X X X

Group 4 - - X X X X X X X

Groups 5 and 6 - - - X X X X X X

NOTE: An X shows that inspection of the tension tie at that location is necessary.

3. If no cracks are found, continue to PART 3. Do the inspection given in FIGURE 8 again at the time

given in Paragraph 1.E., Compliance.

NOTE: As an alternative, modify all affected tension ties as given in FIGURE 3. Do inspections

of the modified tension ties as given in PART 2.

4. If cracks are found in the aft channel, repair as given in FIGURE 3 before any more flights. Do

inspections of the repaired tension ties as given in PART 2, at the times given in Paragraph 1.E.,

Compliance.

NOTE: – Continue to do inspections of affected tension ties that have not been repaired or

modified. Do the inspection given in FIGURE 8 again at the time given in Paragraph

1.E., Compliance.

– If the repair given in FIGURE 3 does not completely remove cracks in the aft channel,

contact Boeing for repair instructions and do the repair.

5. Continue to PART 3.

PART 5 - MODIFICATION (More Work)

1. Remove the ceiling access panels in the main passenger cabin from STA 780 to 940. Refer to

747-100/200/300 AMM 25-22-01.

2. For any tension tie locations that have not previously been repaired or modified as given in this

service bulletin, do the modification as given in FIGURE 3.

3. Do inspections of the modified tension ties as given in PART 2 - AFTER MODIFICATION

INSPECTION PROGRAM, at the times given in Paragraph 1.E., Compliance.

4. Restore the airplane as given in PART 3 - RESTORATION.

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FIGURE 1: THIS FIGURE IS DELETED (REVISION 2)

(SHEET 1 OF 1)

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FIGURE 2: TENSION TIE DETAILED INSPECTION

(SHEET 1 OF 2)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

Step Task Name Identification Qty More Data

1 Inspect Tension Tie - - (a)

(a) Do a detailed inspection for cracks in the outboard 30 inches of the tension tie. Do the inspection at both

ends of the tension tie.

FIGURE 2: TENSION TIE DETAILED INSPECTION

(SHEET 2 OF 2)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 1 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 2 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 3 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 4 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 5 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 6 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 7 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 8 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 9 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 10 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 11 OF 14)

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FIGURE 3: REPAIR OR MODIFICATION

(SHEET 12 OF 14)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY

numbers shown below are the number of parts necessary for one tension tie on one side of the airplane.

NOTE: The figure shows two alternate aft channel trims. Any trim line that is between those shown in the figure

is acceptable. At least five fasteners in each row are necessary inboard of the trim line.

Step Task Name Identification Qty More Data

1 Remove Fasteners - 21 - 28 (a)

2 Remove / Keep Plate - 1 -

3 Trim Aft Channel - 1 -

4 Remove Trimmed Section - 1 -

to match adjacent

structure.

Paint Aft Channel - 1 5

Install (b) (c) Repair Strap A 1 at STA 780.

6

Repair Strap B 1 at STA 800.

Repair Strap C 1 at STA 820.

Repair Strap D 1 at STA 840.

Repair Strap E 1 at STA 860.

Repair Strap F 1 at STA 880.

Repair Strap G 1 at STA 900.

Repair Strap H 1 at STA 920.

at STA 940 for

Groups 1, 4, 5, and

7.

Repair Strap I 1

at STA 940 for

Groups 2, 3, and 6.

Repair Strap J 1

7 Install (b) Plate (Kept) - 1

(a) Number of fasteners removed depends on trim line and tension tie location.

(b) Install with BMS 5-95 sealant.

(c) Trim the repair strap as necessary for installation.

FIGURE 3: REPAIR OR MODIFICATION

(SHEET 13 OF 14)

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ALERT ALERT
The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure.

A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the

number of fasteners necessary for this figure.

If the grip length shown is not available at Boeing, fasteners supplied in kits may be one grip length longer than

indicated. Also, if any of the fastener part numbers are not available or have been superseded, substitute

fasteners may be supplied in Boeing kits.

CODE NAME PART NUMBER HOLE DIA NOTES

Install with BMS 5-95

sealant.

A Bolt BACB30MY6K( )X 0.2026 - 0.2036

Collar BACC30M6

Install with BMS 5-95

sealant.

B Bolt BACB30MY6K4Y 0.216 - 0.219

Collar BACC30R6

Install with BMS 5-95

sealant.

0.2495 - 0.2505

(a)

C Bolt BACB30MY8K4

Collar BACC30M8

(a) Before the hole is made larger, do open hole HFEC inspections at these locations. Use 747 NDT Manual

Part 6, 51-00-00, Procedure 1, 11, or 16. If no cracks are found, make the fastener holes the size given

in the table.

FIGURE 3: REPAIR OR MODIFICATION

(SHEET 14 OF 14)

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FIGURE 4: THIS FIGURE IS DELETED (REVISION 2)

(SHEET 1 OF 1)

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FIGURE 5: THIS FIGURE IS DELETED (REVISION 2)

(SHEET 1 OF 1)

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ALERT ALERT
FIGURE 6: AFTER MODIFICATION INSPECTION

(SHEET 1 OF 2)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

Step Task Name Identification Qty More Data

1 Inspect Tension Tie - - (a)

(a) Do a detailed inspection for cracks in the outboard 30 inches of the tension tie. Do the inspection at both

ends of the tension tie.

FIGURE 6: AFTER MODIFICATION INSPECTION

(SHEET 2 OF 2)

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ALERT ALERT
Repair Strap Dimension

W X Y Z

A 1.4 11.8 9.8 10.6

B 1.0 12.2 11.5 10.6

C 1.1 12.1 11.1 10.6

F 1.3 13.1 11.7 10.0

H 1.7 14.6 12.5 13.3

I 1.3 14.1 12.4 13.6

J 1.4 14.4 13.1 14.3

FIGURE 7: REPAIR STRAP FABRICATION

(SHEET 1 OF 3)

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Repair Strap Dimension

X Y

D 11.1 12.8

E 11.6 13.5

G 12.0 14.3

FIGURE 7: REPAIR STRAP FABRICATION

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY

numbers shown below are the number of parts necessary for the airplane..

STEP TASK NAME PART NUMBER QTY MORE DATA

1 Make Repair Strap A 2 0.071 thick 2024-T3

B 2

C 2

F 2

H 2

I 2

J 2

2 Make Repair Strap D 2 0.071 thick 2024-T3

E 2

G 2

3 Paint Repair Strap - - One coat BMS 10-11, Type I

FIGURE 7: REPAIR STRAP FABRICATION

(SHEET 3 OF 3)

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FIGURE 8: TENSION TIE HIGH FREQUENCY EDDY CURRENT INSPECTION

(SHEET 1 OF 3)

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FIGURE 8: TENSION TIE HIGH FREQUENCY EDDY CURRENT INSPECTION

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

Step Task Name Identification Qty More Data

1 Inspect Tension Tie - - (a)

(a) Do a surface high frequency eddy current (HFEC) inspection for cracks on the edge of the radius of the

tension tie aft channel at the two locations shown. Do the inspection at both ends of the tension tie. Refer

to 747 NDT Manual Part 6, 51-00-00, Procedure 4 or 23, as an accepted procedure.

FIGURE 8: TENSION TIE HIGH FREQUENCY EDDY CURRENT INSPECTION

(SHEET 3 OF 3)

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ALERT ALERT
APPENDIX A: INSPECTION TO ENSURE STRUCTURAL INTEGRITY OF AIRFRAME

A structural reassessment of the 747 airplane has been conducted under the requirements of Federal Aviation

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as

amended in 1978, to ensure safe operation of 747 airplanes throughout their operational life.

Table 1 is a summary of the inspection and modification actions specified in Paragraph 3.B., Work Instructions.

These inspection and modification actions are recommended for the detection and prevention of cracks in the

upper deck tension ties from STA 780 to 940. The failure of more than one tension tie can result in rapid

depressurization of the airplane.

Any cracks in the forward channel of an upper deck tension tie should be repaired before any more flights. Do

this unless specifically approved by your cognizant regulatory agency.

Please report any discrepancies using the reporting system described in this addendum.

TABLE 1: SUMMARY OF FLIGHT SAFETY INSPECTION PROGRAM

Repeat Inspection IntervalAirplane Condition Inspection Method Inspection Threshold

Before the accumulation of 3,000 flight cycles.

1,000 flight cycles after

July 27, 1994.

Service Bulletin 747- Detailed Inspection

53A2371 Repair or Modification Not Installed

Concurrent with the next 3,000 flight cycles.

planned detailed inspection.

Surface High Frequency

Eddy Current (HFEC) Inspection

(a)

Within 10,000 flight cycles 6,000 flight cycles.

after Repair or Modification

Service Bulletin 747- Detailed Inspection

53A2371 Repair or Modification Installed

(a) For airplanes that cannot incorporate the surface HFEC inspection at the next planned detailed inspection,

do the first surface HFEC inspection within 3,000 flight cycles after the Revision 2 date of this service

bulletin.

Boeing requests that operators use the following Structural Significant Item (SSI) Reporting System to report

any discrepancies that are found during accomplishment of a Flight Safety Inspection.

1. Upon recognition of a discrepancy, the following information should be sent to Boeing:

Heading: ATTENTION - SSI DISCREPANCY - SERVICE BULLETIN RELATED

– Service Bulletin Number

– Airplane serial number upon which discrepancy was found

– Identification of structural item found damaged

– Flight-cycles and hours on damaged item

– Location and description of damage including direction and size

– When discovered and inspection method used.

APPENDIX A: FLIGHT SAFETY SECTION

(SHEET 1 OF 2)

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ALERT ALERT
Send the report through Boeing Field Service Representative or directly to:

747 Airline Support

2. An Operator's Follow-up Report containing all available pertinent data relative to the structural

discrepancy shall be sent to Boeing. A summary of the information that should be reported is shown

in the SSI DISCREPANCY REPORT form in the Supplemental Structural Inspection Document (SSID),

Boeing Document D6-35022. Operators may use this form or any suitable alternative which contains

the same information.

3. All data and reports dealing with the Flight Safety Inspection Program shall be submitted either through

a Boeing Field Service Representative or directly to:

Boeing Commercial Airplane Group

P.O. Box 3707

Seattle, Washington 98124

Attn: Manager, Airline Support

4. All reports will be reviewed immediately.

5. The Boeing Company will summarize the results of all reported significant data for distribution

semiannually to operators and appropriate Airworthiness Authorities.

APPENDIX A: FLIGHT SAFETY SECTION

(SHEET 2 OF 2)

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ALERT ALERT