Commercial 

Airplanes 737

Service Bulletin

ALERT

Number: 737-57A1308

Original Issue: August 21, 2009

Revision 1: October 01, 2009

ATA System: 5720

SUBJECT: WINGS - Outer Wing - Skins - Lower Wing Skin at Fuel Tank Access Door Cutout

Keyway - Inspection and Change

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.

ECCN: 9E991

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Copyright © 2009 The Boeing Company

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This document includes proprietary information owned by The Boeing Company and/or one or more third parties.

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information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124.

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3.0
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BLANK PAGE
Table of Contents

Revision Transmittal Sheet ............................................ 5

Summary ...................................................... 7

1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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

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

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

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

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

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1. Existing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2. Data supplied with this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

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

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

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 17

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 18

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

FIGURE 1: LEFT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY . . . . . . . . . 21

FIGURE 2: RIGHT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY . . . . . . . . 24

FIGURE 3: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION . . . . . . . . . 27

FIGURE 4: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION . . . . . . . . 30

FIGURE 5: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE . . . 33

FIGURE 6: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE . . 36

FIGURE 7: LEFT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR . . . . . . . . . 39

FIGURE 8: RIGHT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR . . . . . . . . 42

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BOEING SERVICE BULLETIN 737-57A1308

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BLANK PAGE
Commercial 

Airplanes 737

Service Bulletin

ALERT

Revision Transmittal Sheet Number: 737-57A1308

Original Issue: August 21, 2009

Revision 1: October 01, 2009

ATA System: 5720

SUBJECT: WINGS - Outer Wing - Skins - Lower Wing Skin at Fuel Tank Access Door Cutout

Keyway - Inspection and Change

This revision includes all pages of the service bulletin.

COMPLIANCE INFORMATION RELATED TO THIS REVISION

No more work is necessary on airplanes changed in accordance with the original issue of this service bulletin.

Airplane variable numbers YH301, YH302 and YH303 are added to the effectivity of this service bulletin.

REASON FOR REVISION

This revision is sent to complete the approval process. The original issue was inadvertently released without

completion of the full approval process.

These sections are changed:

1. In the Compliance table, the words "after the initial release date" are changed to "after the revision 1 date",

in two places.

2. Airplane variable numbers YH301, YH302 and YH303 are added to the effectivity of this service bulletin.

The data given in Information Notice 737-57-1308 IN 01 is included in this revision.

Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location

of important changes.

Pages with no vertical lines have no important changes.

REVISION HISTORY

Original Issue: August 21, 2009

Revision 1: October 01, 2009

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT

BLANK PAGE
Commercial 

Airplanes 737

Service Bulletin

ALERT

Summary Number: 737-57A1308

Original Issue: August 21, 2009

Revision 1: October 01, 2009

ATA System: 5720

SUBJECT: WINGS - Outer Wing - Skins - Lower Wing Skin at Fuel Tank Access Door Cutout

Keyway - Inspection and Change

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

The inspection and change in this service bulletin will detect and help prevent cracks in the lower wing skins.

Cracks in the lower wing skin, if left undetected could result in the catastrophic structural failure of the wings.

Three operators have reported finding seven cracks, ranging from 0.02 to 0.380 inches in length, emanating

from the keyway of the fuel tank access hole on the wing lower skin between wing rib numbers 8 and 9 on Boeing

777-200LR and 777-300ER airplanes. The fuel tank access door at this location has a fuel measuring stick

installed and the keyway is used to ensure that the fuel measuring stick is oriented correctly when the fuel tank

access door is installed. The crack is believed to be the result of fatigue due to the position of the keyway. The

lower wing skins on the Boeing 737-900ER Series Airplanes have fuel tank access holes with the same

configuration as that of the affected fuel tank access holes on the 777-300ER airplanes. The affected fuel tank

access holes on the 737-900ER are located between ribs 4 and 5, between Wing Station (WSTA) 180 and

WSTA 204.25. These fuel tank access holes are for fuel tank access doors 531BB and 631BB. Although cracks

have not yet been reported on any 737-900ER airplane, damage tolerance analysis shows crack potential for

the 737-900ER lower wing skins at the noted locations. If a crack initiates, and grows unchecked, it could result

in the loss of the lower wing skin load path. The loss of the lower wing skin load path could result in the

catastrophic structural failure of the wing.

Inspection of the keyway will detect cracks in the keyway before the cracks can grow to the point the lower wing

skin load path is lost. Changing the profile of the keyway will improve the fatigue characteristics of the keyway

which will help prevent cracks in the future. The change in the profile of the keyway can also be used to repair

cracks up to 0.030 inch in length.

If any crack is found that is greater than 0.30 inch in length, skin panel replacement may be required. Skin panel

replacement would require significant manpower and extended downtime.

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The change given in this Service Bulletin is incorporated in production on 737-900ER series airplanes from line

number 2990 onwards.

Boeing Service Related Problem (SRP) 777-SRP-57-0222 is related to this service bulletin.

ACTION

Drain and purge the center fuel tank. Remove the fuel tank access doors 531BB and 631BB between wing rib

numbers 4 and 5, between WSTA 180 and WSTA 204.25. Inspect the fuel tank access door cutouts for a keyway.

If a keyway does not exist then no more work is necessary. If a keyway does exist then do a one time High

Frequency Eddy Current (HFEC) inspection of the keyway in the fuel tank access door cutout for cracks. If no

crack is found or any crack found is 0.030 inch in length or less, change the profile of the keyway to obtain a

larger radius and remove the crack, if present. If any crack greater than 0.030 inch is found, contact Boeing for

repair instructions and do the repair. Install the fuel tank access doors 531BB and 631BB.

EFFECTIVITY

737-900ER Airplanes. Refer to Paragraph 1.A., Effectivity 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.

See Paragraph 1.E., Compliance for compliance information.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are available for airplanes in warranty as of May 1, 2008. Please refer to Paragraph

2.B., Industry Support Information.

MANPOWER

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

Operator Supplied Parts/Materials.

Refer to Paragraph 2.A., Material - Price and Availability.

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BOEING SERVICE BULLETIN 737-57A1308

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BLANK PAGE
Commercial 

Airplanes 737

Service Bulletin

ALERT

Number: 737-57A1308

Original Issue: August 21, 2009

Revision 1: October 01, 2009

ATA System: 5720

SUBJECT: WINGS - Outer Wing - Skins - Lower Wing Skin at Fuel Tank Access Door Cutout

Keyway - Inspection and Change

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 airplanes shown below.

Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line

Number, and Serial Number data.

GROUP CONFIGURATION DESCRIPTION

737-900ER Series Airplanes with a keyway in the wing lower skin at

fuel tank access doors 531BB and 631BB.

1 -

Airplane Models:

737-900ER

Variable Number Group

YH001 - YH012 1

YH031 - YH039 1

YH051 - YH055 1

YH101 - YH126 1

YH201 - YH202 1

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Variable Number Group

YH206 - YH207 1

YH301 - YH303 1

YH321 - YH322 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

The inspection and change in this service bulletin will detect and help prevent cracks in the lower wing

skins. Cracks in the lower wing skin, if left undetected could result in the catastrophic structural failure

of the wings.

Three operators have reported finding seven cracks, ranging from 0.02 to 0.380 inches in length,

emanating from the keyway of the fuel tank access hole on the wing lower skin between wing rib

numbers 8 and 9 on Boeing 777-200LR and 777-300ER airplanes. The fuel tank access door at this

location has a fuel measuring stick installed and the keyway is used to ensure that the fuel measuring

stick is oriented correctly when the fuel tank access door is installed. The crack is believed to be the

result of fatigue due to the position of the keyway. The lower wing skins on the Boeing 737-900ER

Series Airplanes have fuel tank access holes with the same configuration as that of the affected fuel

tank access holes on the 777-300ER airplanes. The affected fuel tank access holes on the 737-900ER

are located between ribs 4 and 5, between Wing Station (WSTA) 180 and WSTA 204.25. These fuel

tank access holes are for fuel tank access doors 531BB and 631BB. Although cracks have not yet

been reported on any 737-900ER airplane, damage tolerance analysis shows crack potential for the

737-900ER lower wing skins at the noted locations. If a crack initiates, and grows unchecked, it could

result in the loss of the lower wing skin load path. The loss of the lower wing skin load path could result

in the catastrophic structural failure of the wing.

Inspection of the keyway will detect cracks in the keyway before the cracks can grow to the point the

lower wing skin load path is lost. Changing the profile of the keyway will improve the fatigue

characteristics of the keyway which will help prevent cracks in the future. The change in the profile of

the keyway can also be used to repair cracks up to 0.030 inch in length.

If any crack is found that is greater than 0.30 inch in length, skin panel replacement may be required.

Skin panel replacement would require significant manpower and extended downtime.

The change given in this Service Bulletin is incorporated in production on 737-900ER series airplanes

from line number 2990 onwards.

Boeing Service Related Problem (SRP) 777-SRP-57-0222 is related to this service bulletin.

Revision 1 is sent to complete the approval process. The original issue was inadvertently released

without completion of the full approval process.

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
These sections are changed in Revision 1:

1. In the Compliance table, the words "after the initial release date" are changed to "after the revision

1 date", in two places.

2. Airplane variable numbers YH301, YH302 and YH303 are added to the effectivity of this service

bulletin.

D. Description

Drain and purge the center fuel tank. Remove the fuel tank access doors 531BB and 631BB between

wing rib numbers 4 and 5, between WSTA 180 and WSTA 204.25. Inspect the fuel tank access door

cutouts for a keyway. If a keyway does not exist then no more work is necessary. If a keyway does

exist then do a one time High Frequency Eddy Current (HFEC) inspection of the keyway in the fuel

tank access door cutout for cracks. If no crack is found or any crack found is 0.030 inch in length or

less, change the profile of the keyway to obtain a larger radius and remove the crack, if present. If any

crack greater than 0.030 inch is found, contact Boeing for repair instructions and do the repair. Install

the fuel tank access doors 531BB and 631BB.

Revision 1 - No more work is necessary on airplanes changed in accordance with the original issue of

this service bulletin.

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

Affected Maintenance Zones

Model Zone

737-900ER 531, 631

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

Table 1 in this service bulletin mandatory.

Table 1: Compliance Time For Fuel Access Door Cutout Keyway Inspection and Keyway Profile Change

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

Before 7,500 total -

flight cycles or

1000 flight cycles

after the revision 1

date of this service

bulletin, whichever

occurs later.

Do a one time inspection for a keyway in the

fuel tank access door 531BB and 631BB

cutouts in accordance with Paragraph 3.B.1.d.

All Airplanes

Airplanes that do not have No more work is necessary. - -

a keyway in the fuel tank

access door 531BB and

631BB cutouts.

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
Table 1: Compliance Time For Fuel Access Door Cutout Keyway Inspection and Keyway Profile Change

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

Before 7,500 total -

flight cycles or

1000 flight cycles

after the revision 1

date of this service

bulletin, whichever

occurs later.

Do a one time High Frequency Eddy Current

(HFEC) inspection of the fuel tank access

door 531BB cutout keyway and fuel tank access door 631BB cutout keyway on the left

and right wing in accordance with Paragraph

3.B.2. Part 2 - Fuel Tank Access Door Cutout

Keyway Inspection.

Airplanes that have a keyway in the fuel tank access door 531BB and/or

631BB cutout.

Before further -

flight.

Change the fuel tank access door cutout

keyway profile in accordance with Paragraph

3.B.3. Part 3 - Fuel Tank Access Door Cutout

Keyway Profile Change.

No crack found in fuel

tank access door cutout

keyway

Before further -

flight.

Repair access door cutout keyway in accordance with Paragraph 3.B.4 Part 4 - Fuel

Tank Access Door Cutout Keyway Repair

Any crack found that is

0.030 inch or less in

length in fuel tank access

door cutout keyway

Before further -

flight.

Contact Boeing for repair instructions and do

the repair.

Any crack found that is

greater than 0.030 inch in

length.

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 and change 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.

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
Elapsed

Hours

Task

Hours

Number of

Persons

Task

Open Access 4 19.00 4.75

Inspect for keyway

Left Wing - FIGURE 1 1 0.10 0.10

Right Wing - FIGURE 2 1 0.10 0.10

Inspect for cracking in keyway

Left wing - FIGURE 3 1 1.00 1.00

Right wing - FIGURE 4 1 1.00 1.00

Change Keyway Profile

Left wing - FIGURE 5 1 2.00 2.00

Right wing - FIGURE 6 1 2.00 2.00

Keyway Repair

Left Wing - FIGURE 7 1 2.50 2.50

Right Wing - FIGURE 8 1 2.50 2.50

Close Access 4 7 1.75

TOTAL FOR EACH AIRPLANE (a) (a)

(a) The total task hours and elapsed time will depend on whether any cracks are

found or not during the inspection.

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data

a. Boeing Service Related Problem (SRP) 777-SRP-57-0222.

b. Standard Overhaul Practices Manual (SOPM) 20-10-03, 20-43-03.

c. 737 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00 Figure 4 and Figure 23.

d. 737-600/700/800/900 Aircraft Maintenance Manual (AMM) 28-11-00, 28-11-31, 28-26-00.

2. Data supplied with this Service Bulletin

None.

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BOEING SERVICE BULLETIN 737-57A1308

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

None.

K. Publications Affected

1. Publications:

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 affects FCS but no new DTIs are necessary.

L. Interchangeability and Intermixability of Parts

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

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
2. MATERIAL INFORMATION

A. Material - Price and Availability

None.

B. Industry Support Information

Boeing warranty remedies are available for 737 airplanes in warranty as of May 1, 2008. For task hour

and material reimbursement for airplanes in warranty as of that date, send a warranty claim to Boeing

Commercial Airplanes Group - Warranties.

C. Parts Necessary For Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

The following parts or materials are necessary to do the change in this service bulletin. Parts and

materials in the manuals given in Paragraph 1.J., References, can also be necessary. Examine

operator supply to make sure all necessary parts and materials are available.

Part Number / Specifica- QTY Name Notes

tion

Type 2, Class A 2 Oz. Chemical Conversion Coating (b)

BMS 10-20, TYPE II 4 Oz. Corrosion Resistant Finish (a)

(a) See the Qualified Products List at the end of the Boeing Material Specification

(BMS) for supplier data.

(b) Refer to SOPM 20-43-03 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.

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
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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BOEING SERVICE BULLETIN 737-57A1308

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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 is plus or minus 0.03 inch

5. 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.

B. WORK INSTRUCTIONS

1. PART 1: PREPARATION

a. Defuel the center fuel tank. Refer to 737-600/700/800/900 AMM 28-26-00 as an accepted

procedure.

b. Purge the center fuel tank and prepare for entry. Refer to 737-600/700/800/900 AMM 28-11-00

as an accepted procedure.

c. Remove fuel tank access doors 531BB (left wing) and 631BB (right wing). Refer to

737-600/700/800/900 AMM 28-11-31 as accepted procedures.

d. Do an inspection for a keyway in the the fuel tank access door 531BB cutout in accordance

with FIGURE 1 and the fuel tank access door 631BB cutout in accordance with FIGURE 2.

(1) If the access door cutout does not have a keyway then no more work is necessary. Do

5. PART 5 - Restoration.

(2) If the access door cutout does have a keyway then do 2. PART 2 - Fuel Tank Access

Door Cutout Keyway Inspection.

2. PART 2: FUEL TANK ACCESS DOOR CUTOUT KEYWAY INSPECTION

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BOEING SERVICE BULLETIN 737-57A1308

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a. Do a High Frequency Eddy Current (HFEC) inspection of the fuel tank access door 531BB

cutout for cracks at the keyway in accordance with FIGURE 3.

(1) If no crack is found, do 3. PART 3 - Fuel Tank Access Door Cutout Keyway Profile Change.

(2) If any crack is found and the crack is less than or equal to 0.030 inch in length, do 4.PART

4, Fuel Tank Access Door Cutout Keyway Repair.

(3) If any crack greater than 0.030 inch in length is found, contact Boeing for repair instructions

and do the repair.

b. Do a High Frequency Eddy Current (HFEC) inspection of the fuel tank access door 631BB

cutout for cracks at the keyway in accordance with FIGURE 4.

(1) If no crack is found, do 3. PART 3 - Fuel Tank Access Door Cutout Keyway Profile Change.

(2) If any crack is found and the crack is less than or equal to 0.030 inch in length, do 4.PART

4, Fuel Tank Access Door Cutout Keyway Repair.

(3) If any crack greater than 0.030 inch in length is found, contact Boeing for repair instructions

and do the repair.

3. PART 3 : FUEL TANK ACCESS DOOR CUTOUT KEYWAY PROFILE CHANGE

a. Change the profile of the fuel tank access door cutout keyway on the left wing in accordance

with FIGURE 5.

b. Change the profile of the fuel tank access door cutout keyway on the right wing in accordance

with FIGURE 6.

4. PART 4: FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

a. Remove the crack in the fuel tank access door cutout keyway on the left wing in accordance

with FIGURE 7.

b. Remove the crack in the fuel tank access door cutout keyway on the right wing in accordance

with FIGURE 8.

5. PART 5: RESTORATION

a. Install fuel tank access doors 531BB (left wing) and 631BB (right wing). Refer to

737-600/700/800/900 AMM 28-11-31 as accepted procedures.

b. Put the airplane back to a serviceable condition.

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 1: LEFT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY

(SHEET 1 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 1: LEFT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Fuel Tank Access Door - 1 (a)

Cutout Keyway

1 Inspect

(a) Inspect the fuel tank access door 531BB cutout for a keyway.

FIGURE 1: LEFT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 2: RIGHT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY

(SHEET 1 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 2: RIGHT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Fuel Tank Access Door - 1 (a)

Cutout Keyway

1 Inspect

(a) Inspect the fuel tank access door 631BB cutout for a keyway.

FIGURE 2: RIGHT WING - ACCESS DOOR CUTOUT - INSPECTION FOR KEYWAY

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 3: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION

(SHEET 1 OF 3)

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Copyright © Unpublished Work - See page 1 for details.

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Revision 1 October 01, 2009 737-57A1308

27 of 44

BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 3: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION

(SHEET 2 OF 3)

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Copyright © Unpublished Work - See page 1 for details.

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28 of 44

BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Do a High Frequency Eddy Current (HFEC) inspection of the indicated area for cracks in accordance with 737 NDT Part 6, 51-

00-00 Figure 4 or Figure 23.

Fuel Tank Access Door - -

Cutout Keyway

1 Inspect

FIGURE 3: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 4: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION

(SHEET 1 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

30 of 44

BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 4: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION

(SHEET 2 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

31 of 44

BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Do a High Frequency Eddy Current (HFEC) inspection of the indicated area for cracks in accordance with 737 NDT Part 6, 51-

00-00 Figure 4 or Figure 23.

Fuel Tank Access Door - -

Cutout Keyway

1 Inspect

FIGURE 4: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - HFEC INSPECTION

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 5: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE

(SHEET 1 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

33 of 44

BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 5: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
NOTE: Material of the wing panel is 2324 T-39 aluminum.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

Machine the wing panel an

additional 0.020 to 0.040 inch

beyond the keyway as an insurance cut. Machine the

wing panel to obtain a 3.0

inch radius at the keyway as

shown. Blend new radius into

the existing cutout with a 3.0

inch return radius.

Fuel Tank Access Door - 1

Cutout Keyway

1 Change

Fuel Tank Access Door - 1 Break sharp edges.

Cutout Keyway

2 Change

Fuel Tank Access Door - 1 Intensity: 0.004A to 0.007A.

Cutout Keyway

3 Shot Peen

Coverage: 2.0.

Shot peen machined edges.

Refer to SOPM 20-10-03 as

an accepted procedure.

Apply to machined areas.

Refer to SOPM 20-43-03 as

an accepted procedure.

Chemical Conversion TYPE 2, CLASS A -

Coating

4 Apply

Apply one coat only to machined areas. Do not apply to

surface where the gasket

seats.

Corrosion Resistant BMS 10-20, TYPE II -

Finish

Apply

FIGURE 5: LEFT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 6: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE

(SHEET 1 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

36 of 44

BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 6: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE

(SHEET 2 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

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37 of 44

BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Machine the wing panel an

additional 0.020 to 0.040 inch

beyond the keyway as an insurance cut. Machine the

wing panel to obtain a 3.0

inch radius at the keyway as

shown. Blend new radius into

the existing cutout with a 3.0

inch return radius.

Fuel Tank Access Door - 1

Cutout Keyway

1 Change

Fuel Tank Access Door - 1 Break sharp edges.

Cutout Keyway

2 Change

Fuel Tank Access Door - 1 Intensity: 0.004A to 0.007A.

Cutout Keyway

3 Shot Peen

Coverage: 2.0.

Shot peen machined edges.

Refer to SOPM 20-10-03 as

an accepted procedure.

Apply to machined areas.

Refer to SOPM 20-43-03 as

an accepted procedure.

Chemical Conversion TYPE 2, CLASS A -

Coating

4 Apply

Apply one coat only to machined areas. Do not apply to

surface where the gasket

seats.

Corrosion Resistant BMS 10-20, TYPE II -

Finish

Apply

FIGURE 6: RIGHT WING - ACCESS DOOR CUTOUT KEYWAY - KEYWAY PROFILE CHANGE

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 7: LEFT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

(SHEET 1 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

39 of 44

BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 7: LEFT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

(SHEET 2 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

40 of 44

BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Machine the wing panel to

obtain a 3.0 inch radius at the

keyway as shown.

Fuel Tank Access Door - 1

Cutout Keyway

1 Change

Move the radius to a maximum of 0.030 inch from the

keyway as required to remove the crack. Maintain a

125 microinch or better surface finish.

Do a High Frequency Eddy

Current (HFEC) inspection of

the machined areas for

cracks in accordance with

737 NDT Part 6, 51-00-00

Figure 4 or Figure 23. If a

crack is found after the keyway has been machined,

contact Boeing for additional

instructions and do the repair.

Fuel Tank Access Door - 1

Cutout Keyway

2 Inspect

Machine the wing panel an

additional 0.020 to 0.040 as

an insurance cut to fully remove the crack. Keep a 3.0

inch radius at the keyway as

shown. Blend the new radius

into the existing cutout with a

3.0 inch return radius.

Fuel Tank Access Door - 1

Cutout Keyway

3 Change

Fuel Tank Access Door - 1 Break sharp edges.

Cutout Keyway

4 Change

Fuel Tank Access Door - 1 Intensity: 0.004A to 0.007A.

Cutout Keyway

5 Shot Peen

Coverage: 2.0.

Shot peen machined edges.

Refer to SOPM 20-10-03 as

an accepted procedure.

Apply to machined areas.

Refer to SOPM 20-43-03 as

an accepted procedure.

Chemical Conversion TYPE 2, CLASS A -

Coating

6 Apply

Apply one coat only to machined areas. Do not apply to

surface where the gasket

seats.

Corrosion Resistant BMS 10-20, TYPE II -

Finish

Apply

FIGURE 7: LEFT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
FIGURE 8: RIGHT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

(SHEET 1 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

42 of 44

BOEING SERVICE BULLETIN 737-57A1308

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

numbers shown below are the number of parts necessary for one side of the airplane.

FIGURE 8: RIGHT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

(SHEET 2 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

43 of 44

BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

Machine the wing panel to

obtain a 3.0 inch radius at the

keyway as shown.

Fuel Tank Access Door - 1

Cutout Keyway

1 Change

Move the radius to a maximum of 0.030 inch from the

keyway as required to remove the crack. Maintain a

125 microinch or better surface finish.

Do a High Frequency Eddy

Current (HFEC) inspection of

the machined areas for

cracks in accordance with

737 NDT Part 6, 51-00-00

Figure 4 or Figure 23. If a

crack is found after the keyway has been machined,

contact Boeing for additional

instructions and do the repair.

Fuel Tank Access Door - 1

Cutout Keyway

2 Inspect

Machine the wing panel an

additional 0.020 to 0.040 as

an insurance cut to fully remove the crack. Keep a 3.0

inch radius at the keyway as

shown. Blend the new radius

into the existing cutout with a

3.0 inch return radius.

Fuel Tank Access Door - 1

Cutout Keyway

3 Change

Fuel Tank Access Door - 1 Break sharp edges.

Cutout Keyway

4 Change

Fuel Tank Access Door - 1 Intensity: 0.004A to 0.007A.

Cutout Keyway

5 Shot Peen

Coverage: 2.0.

Shot peen machined edges.

Refer to SOPM 20-10-03 as

an accepted procedure.

Apply to machined areas.

Refer to SOPM 20-43-03 as

an accepted procedure.

Chemical Conversion TYPE 2, CLASS A -

Coating

6 Apply

Apply one coat only to machined areas. Do not apply to

surface where the gasket

seats.

Corrosion Resistant BMS 10-20, TYPE II -

Finish

Apply

FIGURE 8: RIGHT WING - FUEL TANK ACCESS DOOR CUTOUT KEYWAY REPAIR

(SHEET 3 OF 3)

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: August 21, 2009

Revision 1 October 01, 2009 737-57A1308

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BOEING SERVICE BULLETIN 737-57A1308

ALERT ALERT