### Commercial **Airplanes** 

# 707 Service Bulletin **ALERT Number: A3537**  Original Issue: January 30, 2012 ATA System: 5410 **SUBJECT:** NACELLE - Inboard and Outboard Nacelle Strut Midspar Fitting - Inspection Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). 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. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2012 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, 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 the Boeing livery 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BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 1 of 36 5.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 2 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**

BLANK PAGE**Table of Contents** Summary...................................................... 5 1. PLANNING INFORMATION ........................................ 9 A. Effectivity................................................ 9 1. Airplanes............................................. 9 2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1. Existing Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2. Data supplied with this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3. Installation Drawings Used in the Preparation of this Service Bulletin. . . . . . . . . . . . 18 K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 C. Parts Necessary For Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1. Kits/Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2. Parts and Materials Supplied by the Operator. . . . . . . . . . . . . . . . . . . . . . . . 19 3. Parts Modified and Reidentified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4. Parts Removed and Not Replaced. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 19 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 FIGURE 1: NACELLE STRUT AND SAILBOAT FAIRING DROOP STRIPE APPLICATION. . . . . . 24 FIGURE 2: NACELLE STRUT DROOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 FIGURE 3: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 FIGURE 5: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT FAIRING AND PANEL INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 3 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 4 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# 707 Service Bulletin **ALERT Summary**  **Number: A3537** Original Issue: January 30, 2012 ATA System: 5410 **SUBJECT:** NACELLE - Inboard and Outboard Nacelle Strut Midspar Fitting - Inspection 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** Accomplishment of the inspections in this service bulletin will make sure that an engine number 1, 2, 3, or 4 nacelle strut has not drooped from its normal position and that the correct inboard and outboard midspar fittings are installed on the engine number 2 and 3 nacelle struts. A drooped nacelle strut indicates that a midspar fitting may have fractured. If an incorrect midspar fitting is installed, a fatigue crack can occur which can cause a fracture of a midspar fitting. A fractured midspar fitting can result in a separation of the nacelle strut and engine from the airplane in flight which could preclude safe flight. Operators have reported more than 45 of the midspar fittings with the 0.38 inch tang transition, cracked on more than 40 airplanes with approximately 9,900 to 63,000 flight hours. There have been several events where the engine and nacelle strut has separated from the airplane. In one instance, the engine number 3 nacelle strut separated from the airplane and contacted the engine number 4 nacelle strut, which also separated from the airplane. This service bulletin gives instructions to inspect for the correct engine number 2 and 3 nacelle strut midspar fittings, apply a droop stripe and inspect the engine number 1, 2, 3, and 4 nacelle strut for droop. Boeing Service Related Problem (SRP) 707-SRP-54-0105 is related to this service bulletin. This table is provided to operators for planning purposes only. Refer to the applicable sections for more information.
**Reference Affected**  **Planning Data** Paragraph 1.A.2., Spares Affected No Spares Affected Paragraph 1.E., Compliance Yes AD Related Paragraph 1.H., Weight and Balance Changes No Weight and Balance Change

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 5 of 36**Reference Affected**  **Planning Data** Paragraph 1.I., Electrical Load Data No Electrical Load Changed Paragraph 1.K., Publications Affected No Publications Affected Paragraph 1.K., Publications Affected No Airplane Flight Operations Affected (Flight CrewOperations Manual and/or FAA Approved Airplane Flight Manual) Paragraph 2.C.1., Kits/Parts No Kits/Parts Required Paragraph 2.C.2., Parts and Materials Supplied by the Operator Yes Operator Supplied Material Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin No Special Tooling Required

**ACTION** Do a general visual inspection of the engine number 1, 2, 3, and 4 nacelle struts for droop below the normal position. Make sure each nacelle strut has not drooped from its normal position. Apply a stripe to the inboard and outboard side of the engine number 1, 2, 3, and 4 nacelle strut if it has not been previously accomplished. If a nacelle strut is drooped below its normal position contact Boeing for further instructions and do the work as instructed by Boeing. Do a detailed inspection of the engine number 2 and engine number 3 nacelle strut inboard and outboard midspar fittings to confirm the correct part is installed. If an incorrect part is found replace the part in accordance with Boeing service bulletin 707-3183. Do a HFEC inspection of the engine number 2 and engine number 3 nacelle strut inboard and outboard midspar fittings, to look for cracks. If a crack indication is found contact Boeing for further instructions and do the work as instructed by Boeing. **NOTE:** You do not need to change the existing droop stripe, if the droop stripe was applied in accordance with Boeing service bulletin 707-3377 requirements. **EFFECTIVITY** 707-100, -100B, -200, -300, -300B, -300C, -400, 720, 720B Airplane(s). Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplane(s). **COMPLIANCE** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. Refer to Paragraph 1.E., Compliance. **INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are not available for the inspection, and/or repair procedures given in this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 6 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT MANPOWER**  **Elapsed Hours Total Task Hours**  **Airplanes** 9.00 18.00 All Airplanes
**MATERIAL INFORMATION** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 7 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 8 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**

### Commercial **Airplanes** 

# 707 Service Bulletin **ALERT Number: A3537**  Original Issue: January 30, 2012 ATA System: 5410 **SUBJECT:** NACELLE - Inboard and Outboard Nacelle Strut Midspar Fitting - Inspection 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 Service Bulletin Index D6-1647 Part 3 for Airplane Variable Number, Line Number, and Serial Number data.

**DESCRIPTION CONFIGURATION**  **GROUP** 707-100, 707-100B, 707-200, 707-300, 707-300B, 707-300C, 707-400, 720, 720B Airplanes. - 1

Airplane Models: 707-100, 707-100B, 707-200, 707-300, 707-300B, 707-300C, 707-400, 720, 720B **Group Variable Number**  1 B0001 - B0029 1 B0101 - B0125 1 B0201 - B0203 1 B0301 - B0306 1 B0401 - B0402 1 B0501 - B0515

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 9 of 36**Group Variable Number**  1 B2001 - B2008 1 B2091 - B2092 1 B2101 - B2116 1 B2191 - B2194 1 B2199 1 B2201 - B2227 1 B2401 - B2403 1 B2501 - B2502 1 B2551 - B2553 1 B2601 - B2608 1 00001 - 00006 1 00101 - 00156 1 00201 - 00205 1 00301 - 00305 1 00401 - 00451 1 00471 - 00475 1 00501 - 00513 1 00601 - 00602 1 00701 - 00703 1 02001 - 02020 1 02101 - 02121 1 02201 - 02207 1 02301 - 02303 1 02401 - 02418 1 04001 - 04005 1 04020 - 04022 1 04101 - 04106 1 04201 - 04218 1 04271 - 04272 1 04301 - 04303 1 05001 - 05060 1 05101 - 05138 1 05201 - 05208

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 10 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT Group**  **Variable Number** 1 05301 - 05312 1 05401 1 05601 - 05605 1 05631 - 05635 1 05701 - 05703 1 05801 - 05802 1 05821 - 05827 1 05831 - 05833 1 05851 - 05854 1 05891 - 05892 1 05921 - 05923 1 05941 - 05942 1 05961 - 05970 1 06001 - 06002 1 06101 1 06401 - 06404 1 06451 1 06461 1 07001 - 07017 1 07041 - 07059 1 07071 - 07081 1 07101 - 07109 1 07181 1 07191 1 07201 - 07215 1 07251 - 07271 1 07401 - 07407 1 07451 - 07458 1 07501 - 07504 1 07601 - 07626 1 07661 - 07662 1 07681 - 07684 1 07701 - 07702

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 11 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT Group**  **Variable Number** 1 07801 - 07821 1 07901 - 07907 1 08001 - 08008 1 08021 1 08051 - 08056 1 08071 - 08077 1 08101 - 08104 1 08121 - 08129 1 08141 - 08144 1 08151 - 08153 1 08171 - 08173 1 08191 - 08192 1 08201 - 08210 1 08221 - 08224 1 08241 - 08244 1 08251 1 08261 1 08271 1 08301 - 08320 1 08324 - 08330 1 08333 1 08401 - 08410 1 08451 - 08452 1 08471 - 08475 1 08501 - 08502 1 08551 - 08553 1 08581 - 08582 1 09001 - 09006 1 09101 - 09107 1 09161 - 09167 1 09201 - 09204 1 09221 - 09223 1 09227

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 12 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT Group**  **Variable Number** 1 09231 - 09232 1 09251 1 09271 1 09281 1 09286 - 09290 1 09411 1 09421 1 09438 1 09441 2. Spares Affected None. **B. Concurrent Requirements** None. **C. Reason** Accomplishment of the inspections in this service bulletin will make sure that an engine number 1, 2, 3, or 4 nacelle strut has not drooped from its normal position and that the correct inboard and outboard midspar fittings are installed on the engine number 2 and 3 nacelle struts. A drooped nacelle strut indicates that a midspar fitting may have fractured. If an incorrect midspar fitting is installed, a fatigue crack can occur which can cause a fracture of a midspar fitting. A fractured midspar fitting can result in a separation of the nacelle strut and engine from the airplane in flight which could preclude safe flight. Operators have reported more than 45 of the midspar fittings with the 0.38 inch tang transition, cracked on more than 40 airplanes with approximately 9,900 to 63,000 flight hours. There have been several events where the engine and nacelle strut has separated from the airplane. In one instance, the engine number 3 nacelle strut separated from the airplane and contacted the engine number 4 nacelle strut, which also separated from the airplane. This service bulletin gives instructions to inspect for the correct engine number 2 and 3 nacelle strut midspar fittings, apply a droop stripe and inspect the engine number 1, 2, 3, and 4 nacelle strut for droop. Boeing Service Related Problem (SRP) 707-SRP-54-0105 is related to this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 13 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT D. Description**  Do a general visual inspection of the engine number 1, 2, 3, and 4 nacelle struts for droop below the normal position. Make sure each nacelle strut has not drooped from its normal position. Apply a stripe to the inboard and outboard side of the engine number 1, 2, 3, and 4 nacelle strut if it has not been previously accomplished. If a nacelle strut is drooped below its normal position contact Boeing for further instructions and do the work as instructed by Boeing. Do a detailed inspection of the engine number 2 and engine number 3 nacelle strut inboard and outboard midspar fittings to confirm the correct part is installed. If an incorrect part is found replace the part in accordance with Boeing service bulletin 707-3183. Do a HFEC inspection of the engine number 2 and engine number 3 nacelle strut inboard and outboard midspar fittings, to look for cracks. If a crack indication is found contact Boeing for further instructions and do the work as instructed by Boeing. **NOTE:** You do not need to change the existing droop stripe, if the droop stripe was applied in accordance with Boeing service bulletin 707-3377 requirements. The work in this service bulletin is done in the maintenance zone(s) given below.
**Affected Maintenance Zones Zone**  **Model** 4-55, 4-56, 4-57, 4-58 707-100, 707-100B, 707-200, 707-300, 707-300B, 707-300C, 707-400, 720, 720B **E. Compliance** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. **Table1: Droop Inspection of the Engine Number 1, 2, 3, and 4 Nacelle Strut, HFEC Inspection for cracks, and Detailed Inspection for Correct Inboard and Outboard Midspar Fittings on the Engine Number 2**  **and 3 Nacelle Struts Repeat Interval**  **(Not to Exceed) Compliance Time (Whichever**  **Occurs Later) Action**  **Condition**

- Within 120 days after the original issue date of this service bulletin. Do a one time detailed inspection on the engine number 2 and engine number 3 nacelle strut midspar fittings to confirm a 1 inch radius on the transition area betweenthe fork and the lug in accordance with Paragraph 3.B., Work Instructions Part 1. All airplanes.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 14 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT Table1: Droop Inspection of the Engine Number 1, 2, 3, and 4 Nacelle Strut, HFEC Inspection for cracks,**  **and Detailed Inspection for Correct Inboard and Outboard Midspar Fittings on the Engine Number 2 and 3 Nacelle Struts**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight Install correct part in ac- cordance with Boeing service bulletin 707-3183. Incorrect midspar fittingpart found on engine number 2 or number 3. 250 flight cycles or 12 months whichever occurs first. Within 120 daysof the original issue date of this Service Bulletin. Within 1,500 flight cycles or 48 monthswhichever occurs first from the replacement of the nacelle strut inboard and outboard midspar fittings.Do a High Frequency Eddy Current (HFEC) inspection for any crack of the visible area of the lug of the inboard and outboard strut midspar fittings on engines number 2 and number 3 in accordance with Paragraph 3.B., Work Instructions Part 2. All airplanes.

Before further flight Contact Boeing for repair instructions and do therepair instructed by Boeing. Any crack is found in the inboard or outboard strut midspar fittings on engines number 2 and number 3. 30 flight cycles. Within 120 days after the original issue date ofthis service bulletin. Within 1,500 flight cycles or 48 months,whichever occurs first, from the replacement of the nacelle strut inboard and outboard midspar fittings.Do a general visual inspection of engine number 1, 2, 3, and 4 nacelle strut for signs of droop inaccordance with Paragraph 3.B., Work Instructions Part 3. (c) All airplanes. (b)

Within 120 days after the original issue date ofthis service bulletin Within 1,500 flight cycles or 48 months,whichever occurs first, from the replacement of the nacelle strut inboard and outboard midspar fittings. Apply the droop stripe to engine number 1, 2, 3,and 4 nacelle strut in accordance with Paragraph 3.B., Work Instructions Part 4. (a) If the nacelle strut has not drooped below its normal position and no droop stripe has been applied in accordance with Boeing service bulletin 707-3377.

- Before further flight. Contact Boeing for repair instructions and do therepair instructed by Boeing. Engine number 1, 2, 3, or 4 nacelle strut droop found.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 15 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT Table1: Droop Inspection of the Engine Number 1, 2, 3, and 4 Nacelle Strut, HFEC Inspection for cracks,**  **and Detailed Inspection for Correct Inboard and Outboard Midspar Fittings on the Engine Number 2 and 3 Nacelle Struts**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition**  (a) You do not need to change the existing droop stripe, if the droop stripe is located in accordance with Boeing service bulletin 707-3377 requirements. (b) After both midspar fittings are replaced on a strut, start inspecting again, performing the initial inspection within 1,500 flight cycles or 48 months, whichever occurs first, from the replacement of both of the nacelle strut inboard and outboard midspar fittings. (c) Checking the alignment of a droop stripe, previously applied per service bulletin 707-3377, is an acceptable method of general visual inspection for signs of nacelle strut droop. Boeing recommends that the general visual inspection of engine number 1, 2, 3, and 4 nacelle strut for signs of droop given in Table 2 below, be done prior to each flight by the flight crew or ground crew. **Table 2: Preflight Droop inspection of the Engine Number 1, 2, 3, and 4 Nacelle Strut. (a) Repeat Interval**  **(Not to Exceed) Compliance Time**  **Action Condition**  Prior to each flight Prior to the next flight Do a general visual in-spection of engine number 1, 2, 3, and 4 nacelle strut for signs of droop inaccordance with Paragraph 3.B., Work Instructions Part 3. (a) All airplanes

(a) This verification is not intended to be mandated by the FAA. It is Boeing's Intention, that this verification will be accomplished by the flight crew or ground crew. The verification in Table 2 does not satisfy the requirements of Table 1. **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. 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 16 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT G. Manpower**  The table below shows an estimate of the task hours necessary to do this inspections 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. **Elapsed Hours Task Hours**  **Number of Persons Task**  1.00 2.00 2 FIGURE 1 2.00 4.00 2 FIGURE 2 4.00 8.00 2 FIGURE 3 2.50 5.00 2 FIGURE 4 2.00 4.00 2 FIGURE 5 11.50 23.00 TOTAL FOR EACH AIRPLANE **H. Weight and Balance Changes** None. **I. Electrical Load Data** Not applicable. **J. References** 1. Existing Data a. Boeing Service Bulletin 707-3183, 707-3377. b. Boeing Service Related Problem (SRP) 707-SRP-54-0105. c. Service Bulletin Index D6-1647. d. Standard Overhaul Practices Manual (SOPM) SOPM 20-30-03, 20-41-02. e. 707 Non Destructive testing Manual 707, 720 NDT Part 6, 51-00-00 Figure 24 f. 707 Maintenance Manual Subjects 12-3-1 2. Data supplied with this Service Bulletin None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 17 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**3. Installation Drawings Used in the Preparation of this Service Bulletin None. **K. Publications Affected** None. **L. Interchangeability and Intermixability of Parts** Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 18 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT 2. MATERIAL INFORMATION**  **A. Material - Price and Availability** None. **B. Industry Support Information** Boeing warranty remedies are not available for the configuration changes inspection, and/or repair procedures given in this service bulletin. **C. Parts Necessary For Each Airplane** 1. Kits/Parts None. 2. Parts and Materials Supplied by the Operator
**Notes Name**  **QTY Part Number /**  **Specification** (a) Primer 4 oz BMS 10-11, Type I (a) Enamel 4 oz BMS 10-11, Type II (a) Corrosion Inhibiting Compound 4 oz BMS 3-23 or BMS3-35 (a) 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 given in Paragraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 19 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 20 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**

BLANK PAGE**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 – Angular tolerance is plus or minus 2 degrees 4. Use the approved fastener and process material substitutions in accordance with SRM Chapter 51. 5. 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. 6. A General Visual Inspection is defined as: A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may require removal or opening of access panels or doors. Stands, ladders or platforms may be required to gain proximity to the area being checked. 7. 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 "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. 8. Boeing Service Letter 707-SL-51-029 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 21 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**9. 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. 10. Where the work instructions include installation of a kept part, a new part with the same part number can be installed as an alternative to the kept part. **B. WORK INSTRUCTIONS** 1. PART 1 - ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION a. Do a detailed inspection of the engine number 2 and engine number 3 nacelle strut midspar fittings to confirm the correct part is installed in accordance with FIGURE 3. (1) If the incorrect part is found, install the correct part in accordance with Boeing service bulletin 707-3183. 2. PART 2 - ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING HFEC INSPECTION a. Do a HFEC inspection of the engine number 2 and engine number 3 nacelle strut midspar fittings for a crack in accordance with FIGURE 4. (1) If any crack is found in the inboard or outboard midspar fittings, contact Boeing for repair instructions and do the repair instructed by Boeing. 3. PART 3 - NACELLE STRUT DROOP INSPECTION a. Do a general visual inspection of the engine number 1, 2, 3, and 4 nacelle struts to make sure the nacelle strut has not drooped below it normal position in accordance with FIGURE 2. **NOTE:** The above inspection is necessary to make sure that the strut is correctly aligned with the trailing edge fairing. The installation of an indication stripe, on a strut that is not aligned correctly, may not warn maintenance personnel of a fractured midspar fitting. (1) If a nacelle strut has drooped below it normal position, contact Boeing for repair instructions and do the repair instructed by Boeing. (2) Repeat the nacelle strut droop inspections at the time given in Paragraph 1.E., Compliance. 4. PART 4 - NACELLE STRUT AND SAILBOAT FAIRING DROOP STRIPE APPLICATION a. If the nacelle strut has not drooped below its normal position and no droop stripe has been applied in accordance with Boeing service bulletin 707-3377, apply the droop stripe to the nacelle strut and sailboat fairing, on each side of the engine number 1, 2, 3, and 4 nacelle strut in accordance with FIGURE 1. **NOTE:** You do not need to change the existing droop stripe, if the droop stripe was applied in accordance with Boeing service bulletin 707-3377 requirements. 5. Part 5 - CLOSE ACCESS

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 22 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**a. Do the strut fairing and panel installation in accordance with FIGURE 5. b. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 23 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 1: NACELLE STRUT AND SAILBOAT FAIRING DROOP STRIPE APPLICATION**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 24 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**More Data Qty**  **Identification Name**  **Task Step**  (a) 8

- Nacelle Strut and Aft Fairing Clean 1 (b)

- BMS 10-11 TYPE I Primer Apply 2 (b)

- BMS 10-11 TYPE II Enamel Apply (a) Clean and mask an area to be painted on both sides of each nacelle strut and sailboat fairing. Refer to SOPM 20-30-03 as an accepted procedure. (b) On both sides of each nacelle, apply a stripe of paint across the nacelle strut and the sailboat fairing. Use a color that contrasts with the color of the part on which the paint is applied. Refer to SOPM 20-41-02 as an accepted procedure.

**FIGURE 1: NACELLE STRUT AND SAILBOAT FAIRING DROOP STRIPE APPLICATION (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 25 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 2: NACELLE STRUT DROOP**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 26 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**More Data Qty**  **Identification Name**  **Task Step**  Do a general visual inspection (a) (b) 8

- Nacelle Strut and Aft Fairing Inspect 1 (a) Look at the nacelle strut to see if it has drooped below normal position. Look at the stripe if present for misalignment. In addition, look at the fairing straps, access panels and fairings between strut and wing for buckles, wrinkles, cracks, elongated holes and loose or broken fasteners. Noticeable nacelle droop or flexure damage to sheet metal may indicate that one or both midspar fittings are broken.(b) The recommended verification, prior to each flight, does not have to be accomplished by a qualified mechanic.

**FIGURE 2: NACELLE STRUT DROOP (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 27 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 3: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION**  **(SHEET 1 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 28 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 3: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION**  **(SHEET 2 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 29 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**More Data Qty**  **Identification Name**  **Task Step** 

- - - Fairing Straps Remove / Keep 1

- - - Midspar Joint Access Panels Remove / Keep

- - - Strut-to-Wing Leading Edge Fairings Remove / Keep 2 (a) 4

- Midspar Fitting Inspect 3 (a) Do a detailed inspection of the engine number 2 and engine number 3 nacelle strut inboard and outboard midspar fittings to make sure the correct part is installed. The correct part can be identified by a 1 inch nominal radius on the transition area between the fork and the lug.

**FIGURE 3: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION (SHEET 3 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 30 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC**  **INSPECTION (SHEET 1 OF 4)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 31 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC**  **INSPECTION (SHEET 2 OF 4)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 32 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

**FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC INSPECTION**  **(SHEET 3 OF 4)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 33 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT More Data**  **Qty Identification**  **Name Task**  **Step** Gain additional access for inspection. (b) (c) (d) - - Upper Portion of Ac- cess Panel Cut 1
This step is not required if the panels have already been cut. HFEC inspect boththe inboard & outboard Midspar Fittings. (a) (e) (f) 2

- Midspar Fitting Inspect 2

(g)

- BMS 3-23 OR BMS 3- 35 Corrosion Inhibiting Compound Apply 3 (a) Perform a HFEC inspection in the areas indicated. Refer to Manual 707, 720 NDT Part 6, 51-00-00 Figure 24 as an accepted procedure. (b) At the outboard midspar fitting, remove upper portion of access panel seating as shown in Detail I. Make forward edge of cutout flush with aft edge of strut skin. Finish raw edges as given in operator's standard procedure. (c) At the inboard midspar fitting, remove upper portion of access panel seating as shown in Detail II. Make forward edge of cutout flush with aft edge of strut skin. Also remove portion of fairing angle level with top of existing circular cutout above fitting lug hole as shown. Finish raw edges as given in operator's standard procedure. (d) If nutplate rivet edge margin interferes with cutout of seating area on access panel, replace the nutplate with one that has a corner type rivet ear. (e) The trimming of material as shown in Details I and II is required for this inspection.(f) Clean the indicated areas of the Midspar Fitting as required for the HFEC inspection. Refer to 707 Maintenance Manual Subject 12-3-1 as an accepted procedure. (g) If no cracks are found in the midspar fittings, spray exposed areas of fittings with organic corrosion inhibitor.

**FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC INSPECTION**  **(SHEET 4 OF 4)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 34 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT FIGURE 5: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT FAIRING AND PANEL**  **INSTALLATION (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 35 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**More Data Qty**  **Identification Name**  **Task Step** 

- - - Strut-to-Wing Leading Edge Fairings Install (Kept) 1

- - - Midspar Joint Access Panels Install (Kept) 2

- - - Fairing Straps Install (Kept)

**FIGURE 5: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT FAIRING AND PANEL INSTALLATION**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 30, 2012 A3537 36 of 36 **BOEING SERVICE BULLETIN A3537 ALERT**  **ALERT**