This sheet transmits REVISION 1 dated August 30, 1985

of Service Bulletin 757-54-0003, "NACELLES/PYLONS - UPPER

LINK BACKUP STRUCTURE MODIFICATION".

NOTE: This revision constitutes a complete reissue.

SUMMARY

This revision is issued to provide tooling information which may be

helpful in accomplishing this bulletin. In addition, Notice of Status

Change 757-54-0003NSC1 has been incorporated.

Airplanes modified per the previous release of this service bulletin do

not require additional work.

A revision bar in the left margin along with this revision number and

date indicates a change. Absence of a revision bar on a page bearing a

'revised' notice means only that existing copy has been moved or that a

minor typographical error has been corrected.

REVISION HISTORY

Original Issue:

Revision 1:

December 14, 1984

August 30, 1985
SUBJECT: NACELLES/PYLONS - UPPER LINK

BACKUP STRUCTURE MODIFICATION

BACKGROUND

Fatigue tests and analysis at Boeing

show that cracks can occur in the

horizontal flanges of the nacelle

strut upper link attachment fitting,

the mid-bulkhead where the fitting

attaches, and the center chord

vertical flange forward of the

attachment.

Crack progression in this area could

affect the integrity of the upper link

attachment and, consequently, the

fail-safe design of the strut-to-wing

attachment.

ACTION (PRR N53101)

ATA: 5451 NO: 757-54-0003

DATE: December 14, 1984

REVISION 1: August 30, 1985

EFFECTIVITY

Line Numbers 2 through 30 and 32

through 34.

MANPOWER

Total Man-Hours - 142

Elapsed Time - 27 Hours

MATERIAL INFORMATION

Kit Delivery Price

012N8258-1 Available No Charge

See Paragraph I. F. for applicable

terms and conditions.

Prior to accumulation of 6000 flight

cycles, modify the nacelle strut upper

spar at the affected areas to prevent

cracking.

Modification consists of fastener

installation changes at the attachment

of the upper link attach fitting to

the mid-bulkhead and replacement of a

stiffener on the lower side of the

upper spar web, just forward of the

bulkhead, on the left and right struts.

On the left strut only, replacement of

a pulley bracket assembly is required

to eliminate attachment of the

assembly to the vertical flange of the

center chord.

On both struts, replacement of the

insulation blankets and replacement of

one heat shield, and rework of the

other, is required to accommodate the

modification.

Summary Page 1 of 1
ATA

SYSTEM: 5451

NO: 757-54-0003

DATE: December 14, 1984

REVISION 1: August 30, 1985

SUBJECT: NACELLES/PYLONS - UPPER LINK BACKUP STRUCTURE MODIFICATION

I. PLANNING INFORMATION

A. Effectivity

1. Airplanes Affected

See Service Bulletin Index Part 3 for cross reference of

Variable Number to Airplane Serial Number.

An equivalent change will be incorporated in production in

accordance with PRR N53101 on applicable airplanes other

than those listed below.

LISTING BY CUSTOMER CODE AND VARIABLE NUMBER

BAB NA201-NA204 NA206-NA213

EAL NA002-NA016

INT NA205 NA214

MON NA401-NA403

LISTING BY VARIABLE NUMBER

NA002-NA016 NA201-NA214 NA401-NA403

2. Spares Affected

None

Dec 14/84

REV. 1: Aug 30/85

757-54-0003

Page 1 of 11
B. Reason

Modification of the nacelle strut at and adjacent to the

attachment of the upper link will reduce the possibility of

fatigue cracks. Crack progression in this area could affect the

integrity of the attachment of the upper link and, consequently,

the fail-safe design of the strut-to-wing attachment.

During fatigue tests at Boeing, cracks were found in the upper

link attach fitting horizontal flange and the upper horizontal

flange of the mid-bulkhead. Several of the fasteners attaching

the fitting to the bulkhead were fractured. A crack was also

found at one of two fastener holes in the vertical flange of the

left strut upper spar center chord where a thrust control pulley

bracket attaches to the chord.

Analysis shows that the horizontal flange cracks and fractured

fasteners resulted from clamp-up and cyclic stresses during

flight. The cyclic stresses were accentuated by inadequate fit

of the tension fasteners through the vertical flange of the

attach fitting and the mid-bulkhead. The crack in the chord

vertical flange at the pulley bracket fastener hole was caused by

vertical bending load in the chord. Tne load initiates at a

change in the chord axial load path and is insufficiently

supported by the one-piece stiffener under the spar upper web

forward of the mid-bulkhead.

Revision 1 is issued to provide tooling information which may be

helpful in accomplishing this bulletin. In addition, Notice of

Status Change 757-54-0003NSC1 has been incorporated.

C. Description

Prior to accumulation of 6000 flight cycles, modify the fastener

installation at the attach fitting for the upper link and replace

a web stiffener forward of the fitting on the left and right

nacelle struts.

On the left nacelle strut, also replace the thrust control system

pulley bracket assembly with one that does not attach to the

strut center chord vertical flange.

Oversizing the eight link fitting attach holes in the

mid-bulkhead upper horizontal flange and installing bushings

which protrude below the flange will prevent flange clamp-up from

the attach bolts, while accommodating the shear loads.

Replacement of the two fasteners through the lower vertical

flange of the link attach fitting and the mating flanges of the

bulkhead with sleeve bolts will provide the necessary

interference fit to accommodate the vertical loads in the fitting.

Dec 14/84 757-54-0003

REV. 1: Aug 30/85 2
On the lower side of the upper spar web forward of the link

attach fitting, replacement of the one-piece stiffener with a

two-piece stiffener will minimize chord bending load.

On the left strut after replacement of the pulley bracket

assembly, the two vacated assembly attach holes in the center

chord vertical flange are filled with sleeve bolts.

On both struts, replacement of the stiffener requires replacement

of the two insulation blankets and forward heat shield and rework

of the aft heat shield.

NOTES: 1. Concurrent incorporation of Boeing Service Bulletin

757-54-2 is suggested on commonly affected airplanes

in the interest of airplane down time savings.

2. Operators may find it convenient to use tool

ME311N5178 to perform the above counterboring and

oversizing operations.

3. Attached to this service bulletin is an Evaluation

Form provided for the purpose of communicating

information to the Boeing organization responsible

for the service bulletin and its contents. The data

you provide will be used to improve the Boeing

Service Bulletin Program.

Please forward this form to your Boeing Field Service

Representative or mail directly to:

Boeing Commercial Airplane Company

P. O. Box 3707

Seattle, Washington 98124

Attention: Manager,

Service Bulletin Engineering

Dec 14/84

REV. 1: Aug 30/85

757-54-0003

3
D. Approval

This service bulletin has been reviewed by the Federal Aviation

Administration (FAA) and the modifications herein comply with the

applicable Federal Aviation Regulations (FAR's) and are FAA

APPROVED.

E. Manpower

Approximately 142 man-hours and a crew of 6 are required to

accomplish this modification per airplane.

The following breakdown of manpower requirements is suggested as

a guide to assist operators in planning and accomplishing this

modification. This estimate is for direct labor performed by an

experienced crew. It does not include setup, planning,

familiarization, cure time, tool acquisition, or lost time.

Factor this estimate as necessary based on your own experience.

Operation

Access

Modification

Restoration and

Operational Check

TOTAL PER AIRPLANE

Crew Size

6

4

6

Man-Hours

Elapsed

Time

(Hours)

8

40

5 4

142

10

9

27

Dec 14/84 757-54-0003

4
F. Material - Price and Availability

The kit identified in Paragraph II.A may be obtained from Boeing

within the terms and conditions defined below. After expiration of

the quotation, price and delivery data will be provided upon request.

The delivery quotation below indicates the date when initial kits

will be available. When source capacity is limited and tooling or

material availability is the pacing factor, operator purchase orders

will receive an allocation from the available quantities based on

receipt date of purchase order by the Spares Department and based on

operator's planned modification schedules. Therefore, operators are

requested to include planned dates of incorporation on their purchase

order.

Kit Number Description Delivery Unit Price

012N8258-1 Kit Available No Charge

Date December 14, 1984

The prices quoted are subject to the terms and conditions of Boeing's

standard purchase order acknowledgement. Quotations are subject to

acceptance within 120 days from date hereon. Prices quoted in United

States Dollars. Terms: Net 30 days.

Items offered at "No Charge" are subject to charge after expiration of

the 120-day period.

Address purchase orders and correspondence pertaining to this

quotation to Director of Spares, and refer to this service bulletin

number.

G. Tooling - Price and Availability

The tooling identified in Paragraph II.C may be rented from Boeing.

Address correspondence pertaining to tools to Director of Spares,

refer to this service bulletin number, and provide the period of

intended possession on your purchase order.

When source capacity is limited, tool allocation will be based on

receipt date of purchase order and operator's planned modification

schedule.

Kit Number Description Rent/Day Rent/Month

ME311N5178 Kit Tool-Strut $237.00 (a) $2,368.00 (a)

Fatigue Rework

(a) A $15.00 handling charge is applied to all rentals.

Operators may, at their option, fabricate their own tool to alleviate

any constraints that may be caused by tool allocation. Therefore,

tool drawing is being supplied in support of this service bulletin.

Dec 14/84 757-54-0003

REV. 1: Aug 30/85 5
H. Weight and Balance

Change in

Weight

(Pounds)

Change in

Moment

(Pound-Inches)

+3107.0

I. References

1. Existing Data:

a. Engineering Change Memo PRR 53101

b. 757 Maintenance Manual Subjects 06-43-00,

29-11-00, 36-00-00, 36-11-15 and 54-51-02

07-11-01,

c. Boeing Service Bulletin 757-54-2 "Nacelle/Pylon

Strut Access Door/Panel Attachment Modification".

2. Data supplied in support of this service bulletin:

Drawing No. Sheet DCN ADCN

012N8258

012N8258

ME311N5178*

PL B 2*,3*

1

1

1,2,3

F

Spar Installation -

Upper Nacelle Strut

Spar Installation -

Upper Nacelle Strut

Kit Tool - Strut Fatigue

Rework

* Supplied in support of Revision 1 of this bulletin.

3. Process Data:

Boeing Process Specifications that are listed on drawings

supplied in support of this service bulletin are not

detailed in this service bulletin since they are common

practices which can be accomplished in accordance with

operator's normal procedures.

J. Publications Affected

Publication Chapter/Section

757 Structural Repair Manual

Dec 14/84

REV. 1: Aug 30/85

757-54-0003

6

Title
II. MATERIAL INFORMATION

A. Parts Required Per Airplane

1. The following kit may be obtained as noted in Paragraph I.F.

NOTE: Only one kit and operator furnished materials listed

in Paragraph II.A.2 are required to modify each

airplane.

012N8258 - KIT, SPAR INSTALLATION - UPPER NACELLE STRUT

-1

Quantity Part Number Nomenclature

012N8258-1 Kit, Spar Installation -

Upper Nacelle Strut

1 012N8258-2 (a) Kit

(a) Contains all parts shipped to operator. See drawing

supplied with bulletin for contents of kit.

2. The following materials are to be furnished by the operator.

Part Number or

Quantity Specification Nomenclature

As Required BMS 10-11, Type I Primer

As Required DC93-006 (a) Sealant

(a) Dow Corning Corp. (V71984)

3901 South Saginaw Road

Midland, Michigan 48641

B. Parts Required to Modify Spares

None

C. Special Tools and Equipment Required

The following tools may be obtained as noted in Paragraph I.G.

ME311N5178 "Kit Tool - Strut Fatigue Rework"

D. Existing Parts Accountability

None

Dec 14/84

REV. 1: Aug 30/85

757-54-0003

7
THIS PAGE INTENTIONALLY LEFT BLANK

757-54-0003

8

Dec 14/84
III. ACCOMPLISHMENT INSTRUCTIONS

NOTE: The following paragraphs outline the general accomplishment

instructions and test requirements. The suggested sequence of

operations and detailed accomplishment instructions are indicated

by circle notes on the figures.

A. Stabilize the airplane on jacks at wing and body Jack Points A,

B, C and D per 757 Maintenance Manual Subject 07-11-01 to prevent

movement during modification.

B. Support weight of engine and strut per 757 Maintenance Manual

Subject 54-51-02 to remove all load from the upper link

attachment to the strut. If engine is removed for any reason,

support weight of strut.

C. Depressurize pneumatic system per 757 Maintenance Manual Subject

36-00-00 and install DO-NOT-OPERATE placards on all pneumatic

system controls.

D. Depressurize the left and right hydraulic systems per 757

Maintenance Manual Subject 29-11-00.

E. Open all affected electrical circuit breakers on the Pll overhead

panel and install DO-NOT-CLOSE placards.

F. Remove or open access panels per 757 Maintenance Manual Subject

06-43-00 to obtain access to the upper and lower side of the

engine strut upper spar web at and immediately forward of the

upper link attachment to the strut.

G. At the upper side of the strut upper spar between Power Plant

Stations 152 and 180, remove system cables and plumbing, as

required, for access to the spar web.

H. In the same area below the spar web, remove the pneumatic system

precooler and ducting, as required, per 757 Maintenance Manual

Subject 36-11-15.

I. Modify the spar structure per Figure 1.

J. Upon completion of modification, reinstall the precooler and all

ducting, plumbing and cables removed for access.

K. Remove engine or strut supports, lower airplane and remove jacks,

pressurize pneumatic and hydraulic systems, restore electrical

power and check operation of affected systems.

L. Reinstall or close all access panels.

Dec 14/84 7 5 7-54-0003

REV. 1: Aug 30/85 9
FIGURE 1. ENGINE STRUT MODIFICATION

757-54-0003

10 Dec 14/84
FIGURE 1. ENGINE STRUT MODIFICATION

Dec 14/84

REV. 1: Aug 30/85

757-54-0003

11
THIS EVALUATION FORM IS PROVIDED FOR THE PURPOSE OF COMMUNICATING INFORMATION TO

THE BOEING ORGANIZATION RESPONSIBLE FOR SERVICE BULLETINS AND THEIR CONTENT. THE

DATA YOU PROVIDE WILL BE USED TO IMPROVE THE BOEING SERVICE BULLETIN PROGRAM.

NOTE: THIS FORM IS NOT INTENDED TO BE USED FOR REQUESTING SERVICE BULLETIN

INCORPORATION INTO BOEING TECHNICAL MANUALS.

757-54-0003 (REV. 1) S/B DATED:

NACELLES/PYLONS - UPPER LINK BACKUP

STRUCTURE MODIFICATION

AUGUST 30, 1985

AIRPLANES AFFECTED

(check one):

PREPARED BY: TITLE:

ORGANIZATION:

EVALUATION:

per S/B effectivity list

per corrected list below:

DATE:

TELEX CODE:

check ONE of the following AND

five circles

- Will accomplish

- Being accomplished

- Have accomplished

- Will not accomplish

- Decision deferred (explain)

check ONE of the following

seven circles.

- Inspection

- Partial incorporation

- Complete incorporation

- Service bulletin intent

- Uneconomical

- Service experience does not justify

- Other (explain below)

COMMENTS: Bulletin Quality, Suggested Improvements, Other.

S/B NO.:

TITLE:

OPERATOR: