Commercial 

Airplanes 757

Service Bulletin

SPECIAL ATTENTION

Number: 757-53-0097

Original Issue: November 22, 2010

ATA System: 5300

SUBJECT: FUSELAGE - Skin - Crown Skin Panel - Station 297 to Station 439, Chem-Milled Step

Above Stringer 4 Left and Stringer 4 Right Lap Joint - Inspection

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

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ECCN: 9E991

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Copyright © 2010 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Unpublished Work - All Rights Reserved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.

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

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3.0
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BLANK PAGE
Table of Contents

Summary ...................................................... 5

1. PLANNING INFORMATION ........................................ 9

A. Effectivity ................................................ 9

1. Airplanes ............................................. 9

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1. Existing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2. Data supplied with this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3. Installation Drawings Used in the Preparation of this Service Bulletin . . . . . . . . . . . . 16

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

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: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL DETAILED INSPECTION - OPTION

A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

FIGURE 2: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SLIDING PROBE EC INSPECTION

- OPTION B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

FIGURE 3: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SPOT PROBE MFEC INSPECTION

-OPTION C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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BLANK PAGE
Commercial 

Airplanes 757

Service Bulletin

SPECIAL ATTENTION

Summary Number: 757-53-0097

Original Issue: November 22, 2010

ATA System: 5300

SUBJECT: FUSELAGE - Skin - Crown Skin Panel - Station 297 to Station 439, Chem-Milled Step

Above Stringer 4 Left and Stringer 4 Right Lap Joint - Inspection

BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

Two operators reported cracking on two airplanes in the Body Station (STA) 297 to STA 439 crown skin panel.

The cracking is attributed to fatigue. Cracking may initiate at multiple locations on the interior surface, along the

chem-milled step edges above the stringer 4L or 4R lap splices of the skin. Without inspection for cracks, multiple

site cracks could link together and rapidly progress through the skin. A long crack could result in pressure venting

and a controlled decompression of the airplane.

One reported crack was 10.75-inches long midway between STA 420 and STA 439. The crack was just above

the lap joint at stringer 4L common to the chem-milled step. The airplane had 24,631 flight cycles. On another

airplane the operator reported an opening in the fuselage approximately 12 inches by 18 inches above and aft

of the passenger entry doorway. One edge of the opening was common to the chem-milled step above stringer

4L. Additionally a 1.3" crack was found in the skin forward of the opening in the adjacent skin bay also in the

chem-milled step above stringer 4L. The airplane had 22,450 flight cycles.

This service bulletin gives inspection for cracks along the chem-milled pocket above the lap joints at Stringer 4

left and right side, between Body Stations 297 and 439. Accomplishment of this service bulletin will make sure

that cracks are found and repaired.

Boeing Service Related Problem (SRP) 757-SRP-53-0368 is related to this service bulletin.

ACTION

Get access to the exterior of the skin lap joint at stringer S-4 on the left and right sides of the airplane, between

STA 297 and STA 439. Do either a sliding probe external eddy current (EC), a spot probe mid frequency eddy

current (MFEC) or a detailed inspection for cracking of the STA 297 to STA 439 crown skin panel at the edge

of the chem-milled pockets above stringer S-4L and S-4R lap joints as described and at the times specified in

Paragraph 1.E., Compliance. If any crack is found, contact Boeing for damage removal and repair instuctions

and do the repair. Repeat the sliding probe EC, spot probe MFEC or detailed inspection at the times given in

Paragraph 1.E., Compliance.

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EFFECTIVITY

757-200, 757-200CB, 757-300 Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes.

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

At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent

revision or Information Notice will address the warranty remedies available, if any.

MANPOWER

Airplanes Total Task Hours Elapsed Hours

Option A: External de- 1.00 1.00

tailed inspection

Option B: External Sliding 1.00 1.00

Probe Eddy Current Inspection

Option C: External Spot 3.00 3.00

Probe Middle Frequency

Eddy Current inspection

MATERIAL INFORMATION

None.

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BLANK PAGE
Commercial 

Airplanes 757

Service Bulletin

SPECIAL ATTENTION

Number: 757-53-0097

Original Issue: November 22, 2010

ATA System: 5300

SUBJECT: FUSELAGE - Skin - Crown Skin Panel - Station 297 to Station 439, Chem-Milled Step

Above Stringer 4 Left and Stringer 4 Right Lap Joint - Inspection

BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

Refer to Service Bulletin Index Document D624N001 Part 3 for Airplane Variable Number, Line

Number, and Serial Number data.

GROUP CONFIGURATION DESCRIPTION

1 - 757 Passenger Airplanes

Airplane Models:

757-200, 757-200CB, 757-300

Variable Number Group

NA001 - NA028 1

NA191 - NA199 1

NA201 - NA239 1

NA301 - NA305 1

NA341 - NA352 1

NA391 - NA399 1

NA401 - NA408 1

NA441 - NA447 1

NA501 - NA586 1

NB001 - NB004 1

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Variable Number Group

NB021 - NB023 1

NB036 - NB041 1

NB051 - NB053 1

NB061 - NB073 1

NB079 1

NB131 - NB148 1

NB161 - NB162 1

NB166 - NB168 1

NB201 - NB204 1

NB221 - NB228 1

NB230 1

NB236 1

NB239 1

NB261 - NB267 1

NB291 - NB299 1

NB301 - NB302 1

NB311 - NB312 1

NB321 - NB331 1

NB421 - NB438 1

NB446 1

NB451 - NB454 1

NB501 - NB523 1

NB561 1

NB571 1

NB581 - NB583 1

NC001 - NC033 1

NC041 - NC042 1

NC051 - NC052 1

NC056 - NC062 1

NC066 - NC084 1

NC091 - NC094 1

NC151 1

NC161 1

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BOEING SERVICE BULLETIN 757-53-0097
Variable Number Group

ND001 - ND007 1

ND011 - ND059 1

ND111 - ND113 1

ND161 - ND199 1

ND201 - ND203 1

ND221 - ND225 1

ND241 - ND248 1

ND301 - ND322 1

ND401 1

ND891 1

ND895 1

NE001 - NE008 1

NE011 - NE088 1

NE091 - NE094 1

NE141 - NE150 1

NE161 - NE177 1

NE201 - NE204 1

NE301 - NE302 1

NE311 - NE325 1

NJ001 - NJ004 1

NJ031 - NJ032 1

NJ551 - NJ555 1

NL001 - NL002 1

NL006 - NL017 1

NL101 - NL109 1

NL141 1

NL601 - NL616 1

NN001 - NN002 1

NN051 - NN052 1

NP901 - NP904 1

NT201 - NT202 1

NT231 - NT234 1

NT237 - NT240 1

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BOEING SERVICE BULLETIN 757-53-0097
Variable Number Group

NT242 1

NT245 - NT248 1

NT281 - NT289 1

NT341 - NT347 1

NT351 - NT360 1

NT371 - NT373 1

NT375 - NT379 1

NT381 - NT386 1

NT401 - NT409 1

NT411 - NT412 1

NT426 - NT427 1

NT431 - NT432 1

NT436 - NT438 1

NT441 - NT442 1

NT446 1

NT701 - NT769 1

NT791 - NT796 1

NT861 - NT862 1

NT881 - NT885 1

NT901 - NT916 1

NT971 - NT985 1

NU031 - NU038 1

NU701 - NU705 1

NU721 - NU728 1

NU731 - NU732 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

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BOEING SERVICE BULLETIN 757-53-0097
C. Reason

Two operators reported cracking on two airplanes in the Body Station (STA) 297 to STA 439 crown

skin panel. The cracking is attributed to fatigue. Cracking may initiate at multiple locations on the interior

surface, along the chem-milled step edges above the stringer 4L or 4R lap splices of the skin. Without

inspection for cracks, multiple site cracks could link together and rapidly progress through the skin. A

long crack could result in pressure venting and a controlled decompression of the airplane.

One reported crack was 10.75-inches long midway between STA 420 and STA 439. The crack was

just above the lap joint at stringer 4L common to the chem-milled step. The airplane had 24,631 flight

cycles. On another airplane the operator reported an opening in the fuselage approximately 12 inches

by 18 inches above and aft of the passenger entry doorway. One edge of the opening was common

to the chem-milled step above stringer 4L. Additionally a 1.3" crack was found in the skin forward of

the opening in the adjacent skin bay also in the chem-milled step above stringer 4L. The airplane had

22,450 flight cycles.

This service bulletin gives inspection for cracks along the chem-milled pocket above the lap joints at

Stringer 4 left and right side, between Body Stations 297 and 439. Accomplishment of this service

bulletin will make sure that cracks are found and repaired.

Boeing Service Related Problem (SRP) 757-SRP-53-0368 is related to this service bulletin.

D. Description

Get access to the exterior of the skin lap joint at stringer S-4 on the left and right sides of the airplane,

between STA 297 and STA 439. Do either a sliding probe external eddy current (EC), a spot probe

mid frequency eddy current (MFEC) or a detailed inspection for cracking of the STA 297 to STA 439

crown skin panel at the edge of the chem-milled pockets above stringer S-4L and S-4R lap joints as

described and at the times specified in Paragraph 1.E., Compliance. If any crack is found, contact

Boeing for damage removal and repair instuctions and do the repair. Repeat the sliding probe EC, spot

probe MFEC or detailed inspection at the times given in Paragraph 1.E., Compliance.

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

Affected Maintenance Zones

Model Zone

757-200, 757-200CB, 757-300 223, 224

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.

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BOEING SERVICE BULLETIN 757-53-0097
Table 1: STA 297 to STA 439 crown skin panel - Inspections

Repeat Interval

(Not to Exceed)

Compliance Time

(Whichever Occurs Later)

Condition Action

Within 30 days 30 flight cycles(a)

after the original

issue date of

this service bulletin

Before15,000

total flight cycles

Option A: Do an external detailed

inspection of the STA 297 to STA

439 crown skin panel at stringer S4L and S-4R lap joints in accordance with Paragraph 3.B., Work

Instructions, Step 2.a , (d) (e)

All airplanes

Within 30 days 300 flight cycles (b)

after the original

issue date of

this service bulletin

Before 15,000

total flight cycles

Option B: Do an external sliding

probe EC inspection of the STA 297

to STA 439 crown skin panel at

stringer S-4L and S-4R lap joints in

accordance with Paragraph 3.B.,

Work Instructions, Step 2.b , (d) (e)

Within 30 days 200 flight cycles (c)

after the original

issue date of

this service bulletin

Before 15,000

total flight cycles

Option C: Do an external spot probe

MFEC inspection of the STA 297 to

STA 439 crown skin panel at the

stringer S-4L and S-4R lap joints in

accordance with Paragraph 3.B.,

Work Instructions, Step 2.c , (d) (e)

Within 90 days 300 flight cycles (b)

after the original

issue date of

this service bulletin

Option B: Do an external sliding -

probe EC inspection of the STA 297

to STA 439 crown skin panel at

stringer S-4L and S-4R lap joints in

accordance with Paragraph 3.B.,

Work Instructions, Step 2.b , (b) (d)

(e)

Airplanes that

accomplished

Option A as the

initial inspection

Within 90 days 200 flight cycles (c)

after the original

issue date of

this service bulletin

Option C: Do an external spot probe -

MFEC inspection of the STA 297 to

STA 439 crown skin panel at the

stringer S-4L and S-4R lap joints in

accordance with Paragraph 3.B.,

Work Instructions, Step 2.c , (c) (d)

(e)

Contact Boeing for damage removal Before further flight -

and repair instructions and do the

work instructed by Boeing.

Any crack is

found

(a) Perform detailed inspections until the sliding probe EC or the spot probe MFEC methods are performed.

Once the sliding probe EC or the spot probe MFEC inspections are initiated, visuals are not required.

(b) A detailed inspection may be applied no more than once per repeat interval of 300 flight cycles to extend

the sliding probe(EC) repeat interval up to 330 cycles, not to exceed 30 cycles from the time of the detailed

inspection, to allow an airplane to get to a convenient location for inspection.

(c) A detailed inspection may be applied no more than once per repeat interval of 200 flight cycles to extend

the spot probe (MFEC) repeat interval up to 230 cycles, not to exceed 30 cycles from the time of the detailed inspection, to allow an airplane to get to a convenient location for inspection.

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Table 1: STA 297 to STA 439 crown skin panel - Inspections

Repeat Interval

(Not to Exceed)

Compliance Time

(Whichever Occurs Later)

Condition Action

(d) Except, it is not necessary to inspect the edge of the chem-mill pocket under an existing external repair

doubler provided all of the following apply: 1.The repair doubler is 0.050" or thicker 2024-T3 clad sheet;

2. The repair was approved by the FAA or by a Boeing Company Authorized Representative who was

authorized by the FAA to make such findings; 3. The repair doubler extends a minimum of three rows of

fasteners on each side of the chem-milled step in the circumferential direction.

(e) The Boeing STC 757-200 Special Freighter converted airplanes may exclude inspections of the chemmilled pocket edge under the modification doubler between BS 416 and 439 above Stringer 4L and 4R.

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.

G. Manpower

The table below shows an estimate of the task hours necessary to do this inspection 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.

Option A: External detailed inspection

Task Number of Persons Task Hours Elapsed Hours

FIGURE 1 1 1.00 1.00

TOTAL FOR EACH AIRPLANE 1.00 1.00

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BOEING SERVICE BULLETIN 757-53-0097
Option B: External Sliding probe EC inspection

Task Number of Persons Task Hours Elapsed Hours

FIGURE 2 1 1.00 1.00

TOTAL FOR EACH AIRPLANE 1.00 1.00

Option C: External spot probe MFEC inspection

Task Number of Persons Task Hours Elapsed Hours

FIGURE 3 1 3.00 3.00

TOTAL FOR EACH AIRPLANE 3.00 3.00

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data

a. Boeing Service Related Problem (SRP) 757-SRP-53-0368

b. 737 Non-Destructive Testing (NDT) Manual Part 6, 53-30-09, Part 6, 53-30-18, Part 6, 53-30-23

c. 757 Non-Destructive Testing (NDT) Manual part 6, 53-00-10, Part 6, 53-30-14

2. Data supplied with this Service Bulletin

None.

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

Drawing Number Title

CROWN SKIN PANEL INSTL STA 297 TO STA 440 STR 4R TO

STR 4L

141N3310

These drawings were used to prepare this service bulletin. These drawings are not necessary to

make the specified changes, and are not supplied with this service bulletin. These drawings may

not be applicable to all airplane configurations or operators.

K. Publications Affected

1. Publications:

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BOEING SERVICE BULLETIN 757-53-0097
None.

2. Damage Tolerance Based Structural Inspections:

Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue

Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the

Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.

L. Interchangeability and Intermixability of Parts

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

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BLANK PAGE
2. MATERIAL INFORMATION

A. Material - Price and Availability

None.

B. Industry Support Information

At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent

revision or Information Notice will address the warranty remedies available, if any.

C. Parts Necessary For Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

None.

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.

Although no special tools are required, the sliding probe EC procedure (Option B) given in 757 NDT

Part 6, 53-30-14 requires a sliding probe that may not be in the operator's inventory. Refer to 757 NDT

Part 6, 53-30-14 for information about the sliding probe part number.

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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. The instructions identified in Paragraph 3.B., Work Instructions and the Figure(s)

give the recommended sequence of steps. The sequence of steps to do this service

bulletin can be changed.

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

definition of the acronyms.

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

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

– Linear dimensions are in inches

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

or minus 0.03 inch

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

– Angular tolerance is plus or minus 2 degrees

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

Manual (SRM) Chapter 51

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

5. Use the approved fastener and process material substitutions in accordance with

SRM Chapter 51. Alternate fasteners are listed in SRM Chapter 51 and Boeing

Drawing 65-88700.

6. 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.

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.

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8. Boeing Service Letter 757-SL-51-022, 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.

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

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

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

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

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

10. 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.

B. WORK INSTRUCTIONS

1. Get access to the exterior of the skin above the lap joint at stringer S-4 on the left side from Body

Station (STA) 297 to STA 324 and from STA 377.7 to STA 439, and above the lap joint at S-4 on

the right side of the airplane between (STA) 297 and STA 439.

2. Do one of the following inspections at the times given in Paragraph 1.E., Compliance except as

given in the following notes:

NOTE: The Boeing STC 757-200 Special Freighter converted airplanes may exclude inspections

of the chem-milled pocket edge under the modification doubler between BS 416 and 439

above Stringer 4L and 4R.

NOTE: It is not necessary to inspect the chem-mill pocket edge under an existing external repair

or modification doubler provided all of the following apply:

1. The repair doubler is 0.050" or thicker 2024-T3 clad sheet.

2. The repair was approved by the FAA or by a Boeing Company Authorized

Representative who was authorized by the FAA to make such findings.

3. The repair extends a minimum of three rows of fasteners on each side of the

chem-milled step in the circumferential direction.

a. OPTION A: Do an external detailed inspection for cracking of the crown skin panel from STA

297 to STA 324 and from STA 377.7 to STA 439 at the edge of the chem-milled pockets above

S-4L, and from STA 297 to STA 439 at the edge of the chem-milled pockets above S-4R, at

the locations shown in accordance with FIGURE 1.

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(1) If any crack is found, contact Boeing for damage removal and repair instructions and do

the work instructed by Boeing.

(2) Repeat inspections at the times given in Paragraph 1.E., Compliance until EC or MFEC

is done at the time specified in I E, Compliance.

b. OPTION B: Do an external sliding probe Eddy Current (EC) inspection for cracking of the

crown skin panel from STA 297 to STA 324 and from STA 377.7 to STA 439 at the edge of

the chem-milled pockets above S-4L, and from STA 297 to STA 439 at the edge of the

chem-milled pockets above S-4R, at the locations shown in accordance with FIGURE 2.

(1) If any crack is found, contact Boeing for damage removal and repair instructions and do

the work instructed by Boeing.

(2) Repeat inspections at the times given in Paragraph 1.E., Compliance.

c. OPTION C: Do an external spot probe Middle Frequency Eddy Current (MFEC) inspection

for cracking of the crown skin panel from STA 297 to STA 324 and from STA 377.7 to STA

439 at the edge of the chem-milled pockets above S-4L, and from STA 297 to STA 439 at the

edge of the chem-milled pockets above S-4R, at the locations shown in accordance with

FIGURE 3

(1) If any crack is found, contact Boeing for damage removal and repair instructions and do

the work instructed by Boeing.

(2) Repeat inspections at the times given in Paragraph 1.E., Compliance.

3. Put the airplane back to a serviceable condition.

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FIGURE 1: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL DETAILED INSPECTION - OPTION

A

(SHEET 1 OF 3)

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FIGURE 1: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL DETAILED INSPECTION - OPTION

A

(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 Inspect CROWN SKIN PANEL - - (a)

(a) Do an external detailed inspection for cracks in the crown skin panel along the edge of the chem-milled

pocket above the lap joint.

FIGURE 1: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL DETAILED INSPECTION - OPTION

A

(SHEET 3 OF 3)

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FIGURE 2: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SLIDING PROBE EC INSPECTION -

OPTION B

(SHEET 1 OF 3)

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FIGURE 2: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SLIDING PROBE EC INSPECTION -

OPTION B

(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 Inspect CROWN SKIN PANEL - - (a)

(a) Do an external sliding probe EC inspection for cracks in the crown skin panel along the edge of the chemmilled pocket above the lap joint in accordance with 757 NDT Part 6, 53-30-14.

FIGURE 2: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SLIDING PROBE EC INSPECTION -

OPTION B

(SHEET 3 OF 3)

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FIGURE 3: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SPOT PROBE MFEC INSPECTION

-OPTION C

(SHEET 1 OF 3)

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FIGURE 3: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SPOT PROBE MFEC INSPECTION

-OPTION C

(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 Inspect CROWN SKIN PANEL - - (a) (b)

(a) Do an external spot probe MFEC inspection for cracks in the crown skin panel along the edge of the

chem-milled pocket above the lap joint in accordance with 757 NDT Part 6, 53-00-10.

(b) 737 NDT Part 6, 53-30-23 and 737 NDT Part 6, 53-30-09 and 737 NDT Part 6, 53-30-18 are equivalent

to 757 NDT Part 6, 53-00-10 for instrument calibration. Follow this service bulletin for the required inspection

areas.

FIGURE 3: STA 297 TO STA 439 CROWN SKIN PANEL - EXTERNAL SPOT PROBE MFEC INSPECTION

-OPTION C

(SHEET 3 OF 3)

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