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

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laws.

ECCN: 9E991

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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Unpublished Work - All Rights Reserved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,

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5.0
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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

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BOEING SERVICE BULLETIN A3537

ALERT ALERT
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BOEING SERVICE BULLETIN A3537

ALERT ALERT

BLANK PAGE
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.

Planning Data Affected Reference

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

AD Related Yes Paragraph 1.E., Compliance

Weight and Balance Change No Paragraph 1.H., Weight and Balance Changes

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Planning Data Affected Reference

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)

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

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.

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BOEING SERVICE BULLETIN A3537

ALERT ALERT
MANPOWER

Airplanes Total Task Hours Elapsed Hours

All Airplanes 18.00 9.00

MATERIAL INFORMATION

None.

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ALERT ALERT
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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.

GROUP CONFIGURATION DESCRIPTION

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

Variable Number Group

B0001 - B0029 1

B0101 - B0125 1

B0201 - B0203 1

B0301 - B0306 1

B0401 - B0402 1

B0501 - B0515 1

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Variable Number Group

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 1

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ALERT ALERT
Variable Number Group

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 1

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BOEING SERVICE BULLETIN A3537

ALERT ALERT
Variable Number Group

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 1

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ALERT ALERT
Variable Number Group

09231 - 09232 1

09251 1

09271 1

09281 1

09286 - 09290 1

09411 1

09421 1

09438 1

09441 1

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.

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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

Model Zone

707-100, 707-100B, 707-200, 4-55, 4-56, 4-57, 4-58

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)

Condition Action

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 between

the fork and the lug in accordance with Paragraph

3.B., Work Instructions

Part 1.

All airplanes.

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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)

Condition Action

Install correct part in ac- Before further flight -

cordance with Boeing

service bulletin 707-3183.

Incorrect midspar fitting

part found on engine number 2 or number 3.

250 flight cycles or

12 months

whichever occurs

first.

Within 120 days

of the original issue date of this

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 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.

Contact Boeing for repair Before further flight

instructions and do the

repair instructed by Boeing.

Any crack is found in the

inboard or outboard strut

midspar fittings on engines

number 2 and number 3.

Within 120 days 30 flight cycles.

after the original

issue date of

this 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 in

accordance with Paragraph 3.B., Work Instructions Part 3. (c)

All airplanes.

(b)

Within 120 days

after the original

issue date of

this 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.

Contact Boeing for repair Before further flight. -

instructions and do the

repair instructed by Boeing.

Engine number 1, 2, 3, or

4 nacelle strut droop found.

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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)

Condition Action

(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)

Condition Action Compliance Time

Do a general visual in- Prior to the next flight Prior to each flight

spection of engine number 1, 2, 3, and 4 nacelle

strut for signs of droop in

accordance 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.

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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.

Task Number of Persons Task Hours Elapsed Hours

FIGURE 1 2 2.00 1.00

FIGURE 2 2 4.00 2.00

FIGURE 3 2 8.00 4.00

FIGURE 4 2 5.00 2.50

FIGURE 5 2 4.00 2.00

TOTAL FOR EACH AIRPLANE 23.00 11.50

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.

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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.

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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

Part Number / QTY Name Notes

Specification

BMS 10-11, Type I 4 oz Primer (a)

BMS 10-11, Type 4 oz Enamel (a)

II

BMS 3-23 or 4 oz Corrosion Inhibiting Compound (a)

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.

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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.

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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

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a. Do the strut fairing and panel installation in accordance with FIGURE 5.

b. Put the airplane back to a serviceable condition.

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FIGURE 1: NACELLE STRUT AND SAILBOAT FAIRING DROOP STRIPE APPLICATION

(SHEET 1 OF 2)

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

Step Task Name Identification Qty More Data

Nacelle Strut and Aft - 8 (a)

Fairing

1 Clean

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

Apply Enamel BMS 10-11 TYPE II - (b)

(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)

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FIGURE 2: NACELLE STRUT DROOP

(SHEET 1 OF 2)

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

Step Task Name Identification Qty More Data

Do a general visual

inspection (a) (b)

Nacelle Strut and Aft - 8

Fairing

1 Inspect

(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)

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FIGURE 3: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION

(SHEET 1 OF 3)

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FIGURE 3: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTING INSPECTION

(SHEET 2 OF 3)

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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 Remove / Keep Fairing Straps - - -

Midspar Joint Access - - -

Panels

Remove / Keep

Strut-to-Wing Leading - - -

Edge Fairings

2 Remove / Keep

3 Inspect Midspar Fitting - 4 (a)

(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)

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FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC

INSPECTION

(SHEET 1 OF 4)

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FIGURE 4: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT MIDSPAR FITTINGS HFEC

INSPECTION

(SHEET 2 OF 4)

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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)

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Step Task Name Identification Qty More Data

Gain additional access for inspection.

(b) (c) (d)

Upper Portion of Ac- - -

cess Panel

1 Cut

This step is not required if the panels

have already been

cut.

HFEC inspect both

the inboard & outboard Midspar Fittings. (a) (e) (f)

2 Inspect Midspar Fitting - 2

BMS 3-23 OR BMS 3- - (g)

35

Corrosion Inhibiting

Compound

3 Apply

(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)

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FIGURE 5: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT FAIRING AND PANEL

INSTALLATION

(SHEET 1 OF 2)

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

Step Task Name Identification Qty More Data

Strut-to-Wing Leading - - -

Edge Fairings

1 Install (Kept)

Midspar Joint Access - - -

Panels

2 Install (Kept)

Install (Kept) Fairing Straps - - -

FIGURE 5: ENGINE NUMBER 2 AND ENGINE NUMBER 3 NACELLE STRUT FAIRING AND PANEL

INSTALLATION

(SHEET 2 OF 2)

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