This sheet transmitsREVISION 1dated August 30, 1985 of ServiceBulletin 757-54-0003, "NACELLES/PYLONS
- UPPER LINKBACKUP STRUCTUREMODIFICATION". NOTE:This revisionconstitutesa 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 757-54-0003NSC1has been incorporated. Airplanesmodified per the previous release of this service bulletindo not requireadditionalwork. A revision bar in the left margin along with this revision number and date indicatesa change. Absence of a revisionbar on a page bearing a

'revised'noticemeans only that existing copyhas been moved or that a minor typographicalerrorhas been corrected.

REVISIONHISTORY Original Issue: Revision 1: December 14, 1984 August 30, 1985SUBJECT: NACELLES/PYLONS- UPPERLINK BACKUP STRUCTUREMODIFICATION 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 (PRRN53101) 

### 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 TotalMan-Hours - 142 ElapsedTime
- 27Hours MATERIAL INFORMATION Kit Delivery Price 012N8258-1 Available NoCharge See Paragraph I. F. for applicable termsand 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 leftand 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:August30, 1985 

### SUBJECT: NACELLES/PYLONS- UPPERLINKBACKUP STRUCTUREMODIFICATION

I. PLANNING INFORMATION A. Effectivity 1. AirplanesAffected See Service Bulletin Index Part 3 for cross reference of VariableNumber toAirplaneSerial Number. An equivalent change will be incorporated in production in accordance with PRR N53101 on applicable airplanes other than those listedbelow. LISTING BY CUSTOMER CODE AND VARIABLE NUMBER 

### BABNA201-NA204 NA206-NA213 EAL NA002-NA016 INT NA205 NA214 MONNA401-NA403 LISTING BY VARIABLE NUMBER 

### NA002-NA016 NA201-NA214 NA401-NA403 2. SparesAffected None Dec 14/84 REV. 1: Aug 30/85 757-54-0003 Page 1 of 11B. 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-safedesign of the strut-to-wingattachment. 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 fastenerholes in the vertical flange of the left strut upper spar center chord where a thrust control pulley bracketattaches 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 flangeat the pulley bracket fastenerhole 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 forwardof themid-bulkhead. Revision 1 is issued to provide tooling information which may be helpful in accomplishing this bulletin. In addition, Notice of StatusChange 757-54-0003NSC1has been incorporated. C. Description Prior to accumulation of 6000 flight cycles, modify the fastener installationat theattach fitting for theupper 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 chordvertical flange. Oversizing the eight link fitting attach holes in the mid-bulkhead upper horizontal flange and installing bushings which protrude below the flangewill 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 2On the lower side of the upper spar web forward of the link attach fitting, replacement of the one-piece stiffener with a two-piece stiffenerwill minimize chordbending load. On the left strut after replacement of the pulley bracket assembly, the two vacated assembly attach holes in the center chordvertical flangeare filledwith sleevebolts. On both struts, replacementof the stiffener requires replacement of the two insulationblanketsand forwardheat shield and rework of theaft heat shield. NOTES: 1. Concurrent incorporation of Boeing Service Bulletin 757-54-2 is suggested on commonly affected airplanes in the interest ofairplanedown time savings. 2. Operators may find it convenient to use tool ME311N5178 to perform the above counterboring and oversizingoperations. 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 ServiceBulletin Program. Please forward this form to your Boeing Field Service Representativeormail directly to: BoeingCommercialAirplaneCompany P. O. Box 3707 Seattle,Washington 98124 Attention: Manager, ServiceBulletin Engineering

Dec 14/84 REV. 1: Aug 30/85 

### 757-54-0003 3D. Approval This service bulletin has been reviewed by the Federal Aviation Administration (FAA)and themodificationsherein complywith 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 thismodificationperairplane. 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 asnecessarybased on your own experience.

Operation Access Modification Restorationand OperationalCheck TOTAL PERAIRPLANE Crew Size 6 4

6 Man-Hours Elapsed Time (Hours) 8 40
54 142 10

9 27



### Dec 14/84 

### 757-54-0003 4F. Material
- Priceand Availability The kit identified in Paragraph II.A may be obtained from Boeing within the terms and conditions defined below. After expiration of thequotation,priceand deliverydatawill be providedupon 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 Departmentand based on operator's planned modification schedules. Therefore, operators are requested to include planneddates of incorporationon their purchase order. Kit Number Description Delivery Unit Price 012N8258-1 Kit Available NoCharge Date December 14, 1984 The pricesquoted are subject to the terms and conditions of Boeing's standard purchase order acknowledgement. Quotations are subject to acceptancewithin 120 days from date hereon. Prices quoted in United States Dollars. Terms: Net 30 days. Itemsoffered at "NoCharge"are subject to chargeafter expiration of the 120-dayperiod. Address purchase orders and correspondence pertaining to this quotation to Director of Spares, and refer to this service bulletin number. G. Tooling
- Priceand 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 intendedpossessiononyour purchaseorder. 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) FatigueRework (a) A $15.00handlingcharge isapplied toall rentals. Operators may, at their option, fabricate their own tool to alleviate any constraints that may be caused by tool allocation. Therefore, tooldrawing isbeing supplied in supportof this servicebulletin. Dec 14/84 757-54-0003 REV. 1: Aug 30/85 5H. Weightand Balance Change in Weight (Pounds) Change in Moment (Pound-Inches) +3107.0 I. References 1. Existing Data: a. EngineeringChangeMemo PRR 53101 b. 757 Maintenance Manual Subjects 06-43-00, 29-11-00, 36-00-00,36-11-15and 54-51-02 07-11-01,

c. Boeing Service Bulletin 757-54-2 "Nacelle/Pylon Strut AccessDoor/PanelAttachmentModification". 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 NacelleStrut Spar Installation
- UpperNacelle Strut Kit Tool
- Strut Fatigue Rework * Supplied in support of Revision 1 of thisbulletin. 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'snormal procedures. J. PublicationsAffected 

## Publication Chapter/Section 757 StructuralRepairManual

Dec 14/84 REV. 1: Aug 30/85 757-54-0003 6 TitleII. 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- UPPERNACELLE STRUT -1 Quantity PartNumber Nomenclature 012N8258-1 Kit, Spar Installation
- UpperNacelle Strut 1 012N8258-2 (a) Kit (a) Contains all parts shipped to operator. See drawing suppliedwith bulletin for contentsof 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 AsRequired DC93-006 (a) Sealant (a) Dow Corning Corp. (V71984) 3901 South Saginaw Road Midland,Michigan 48641 B. PartsRequired toModify Spares None C. SpecialToolsand EquipmentRequired The following toolsmay be obtainedas noted in ParagraphI.G. ME311N5178 "KitTool
- Strut FatigueRework" D. Existing PartsAccountability None



### Dec14/84 REV. 1: Aug 30/85 

### 757-54-0003 7THIS PAGE INTENTIONALLYLEFTBLANK



### 757-54-0003 8 Dec 14/84III. ACCOMPLISHMENTINSTRUCTIONS NOTE:The following paragraphs outline the general accomplishment instructions and test requirements. The suggested sequence of operationsand detailed accomplishment instructionsare 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 movementduringmodification. 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, supportweight 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 MaintenanceManual Subject 29-11-00. E. Open all affected electrical circuitbreakers on the Pll overhead paneland installDO-NOT-CLOSEplacards. 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, plumbingand cables removed foraccess. K. Remove engine or strut supports, lowerairplaneand remove jacks, pressurize pneumatic and hydraulic systems, restore electrical powerand check operationof affected systems. L. Reinstallor closeallaccess panels.

Dec 14/84 757-54-0003 REV. 1: Aug 30/85 9FIGURE 1. ENGINE STRUTMODIFICATION 757-54-0003 10 Dec 14/84FIGURE 1. ENGINESTRUTMODIFICATION Dec 14/84 REV. 1: Aug 30/85 757-54-0003 11THIS EVALUATION FORM IS PROVIDED FOR THE PURPOSE OF COMMUNICATING INFORMATION TO THE BOEINGORGANIZATION RESPONSIBLE FOR SERVICE BULLETINSAND THEIR CONTENT. THE DATA YOU PROVIDEWILL BE USEDTO IMPROVETHEBOEING SERVICEBULLETIN PROGRAM. NOTE: THIS FORM IS NOT INTENDED TO BE USED FOR REQUESTING SERVICE BULLETIN INCORPORATION INTOBOEING TECHNICALMANUALS. 757-54-0003 (REV. 1) S/B DATED: 

### NACELLES/PYLONS
- UPPER LINK BACKUP STRUCTUREMODIFICATION AUGUST30, 1985

AIRPLANESAFFECTED (checkone): TITLE: PREPARED BY: ORGANIZATION: EVALUATION: per S/B effectivitylist per corrected listbelow: DATE: TELEX CODE:
checkONE of the following AND

five circles

- Willaccomplish

- Being accomplished

- Haveaccomplished

- Willnot accomplish

- Decisiondeferred (explain) checkONE of the following seven circles.

- Inspection

- Partial incorporation

- Complete incorporation

- Servicebulletin intent

- Uneconomical

- Service experiencedoesnot justify

- Other (explainbelow) COMMENTS: BulletinQuality, Suggested Improvements,Other. S/B NO.: TITLE: OPERATOR: