# Boeing Alert Service Bulletin MD90-57A031: No revision named

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- Document: [Boeing Alert Service Bulletin MD90-57A031](https://openairdocs.org/service-documents/boeing/md90-57a031.md)
- Title as filed: SB-MD90-57A031-00--
- Pages: 34
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## Text

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### Page 1

Commercial 
Airplanes
MD90
Service Bulletin
ALERT
Number: MD90-57A031
Original Issue: March 19, 2019
ATA System: 5730
SUBJECT: WINGS - Lower Wing Skin - Inspection of Left and Right Center Wing Lower Skins and
Stringers
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). 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.
9E991ECCN:
Copyright © 2019 Boeing.
Unpublished Work. All Rights Reserved.
Treatment of this document and its content is governed by contract with Boeing. Rights to use this document
are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The
Boeing Company.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and
Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in
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Original Issue: March 19, 2019
MD90-57A031
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2.0

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Table of Contents
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 17
K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 20
3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
FIGURE 1: OPEN ACCESS - CENTER WING LOWER SKIN PANELS . . . . . . . . . . . . . . . . . 24
FIGURE 2: INSPECTION - CENTER WING LOWER SKIN - EDDY CURRENT, LOW FREQUENCY (ETLF)
AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS . . . . . . . . . . . 27
FIGURE 3: CLOSE ACCESS - CENTER WING LOWER SKIN PANELS . . . . . . . . . . . . . . . . 30
APPENDIX A: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE TABLE 1: EDDY CURRENT, LOW
FREQUENCY (ETLF) AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS OF
LEFT AND RIGHT CENTER WING LOWER SKINS AND STRINGERS . . . . . . . . . . 33
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Commercial 
Airplanes
MD90
Service Bulletin
ALERT
SummaryNumber: MD90-57A031Original Issue: March 19, 2019
ATA System: 5730
SUBJECT: WINGS - Lower Wing Skin - Inspection of Left and Right Center Wing Lower Skins and
Stringers
THIS DOCUMENT 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 DOCUMENT
TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS DOCUMENT TO THE
NEW OWNER.
CONCURRENT REQUIREMENTS
None.
BACKGROUND
Accomplishment of this service bulletin will make sure any crack on the left and right center wing lower skins
and stringers at the fastener holes common to Stringers 11 through 22 and around the external bracket angle
at Stringers 18 and 19 is found. If this service bulletin is not done, undetected fatigue cracks may result in the
inability of the structure to sustain limit loads, which could adversely affect the structural integrity of the airplane.
The MD-90 center wing stringers and skins have been identified to potentially be susceptible to cracking, based
on MD-80 service experience. MD-80 and MD-90 wings share the same basic design and have similar stresses.
MD-80 operators have reported finding cracks in the center wing lower stringers, lower stringer end fittings, and
lower forward and aft skins. The cracks in stringers occur at the inboard end where they are joined to the aircraft
centerline by end fittings. Cracks in the end fittings occur at the outboard end where they attach to stringers.
The wing skin cracks occur underneath a cracked stringer. The cause of the cracks has been determined to be
from fatigue. The Boeing Company has not received any reports of cracks on MD90 airplanes.
Boeing Service Related Problem (SRP) MD90-SRP-57-0312 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) MD-90 FTD 57-17001 is related to this service bulletin.
This table is provided to operators for planning purposes only. Refer to the applicable sections for more
information.
ReferenceAffectedPlanning Data
Paragraph 1.A.2., Spares AffectedNoSpares Affected
Paragraph 1.E., Compliance and Paragraph
1.F., Approval
YesAD Related
Paragraph 1.H., Weight and Balance ChangesNoWeight and Balance Change
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ReferenceAffectedPlanning Data
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedNoPublications Affected
Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew
Operations Manual and/or FAA Approved Air-
plane Flight Manual)
Paragraph 2.C.1., Kits/PartsNoKits/Parts Required
Paragraph 2.C.2., Parts and Materials Supplied
by the Operator
YesOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION
Get access to the left and right center wing lower skins, stringers S-11 thru S-22 between Xcw=0 and Xcw=20
under the wing/fuselage fillet panels. Do an Eddy Current, Low Frequency (ETLF) inspection of the left and right
side fastener holes common to stringers 11 thru 22 and the forward and aft skins for any crack and do an Eddy
Current, High Frequency (ETHF) inspection of the lower skin at stringers 18 thru 20 for any crack. If any crack
is found, contact The Boeing Company for repair instructions and do the repair; and repeat the inspections for
any crack in the unrepaired area. If no crack is found, repeat the inspections for any crack.
EFFECTIVITY
All MD-90-30 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
Boeing warranty remedies are not available for the inspection given in this service bulletin.
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 MD90-57A031
ALERT  ALERT
DO AN EDDY CURRENT, LOW FREQUENCY (ETLF)
INSPECTION OF FASTENER HOLES COMMON TO
STRINGERS 11 THRU 22 AND THE FORWARD AND
AFT SKINS FOR ANY CRACK.
DO AN EDDY CURRENT, HIGH FREQUENCY
ETHF) INSPECTION OF THE LOWER SKIN AT
STRINGERS 18 THRU 20 FOR ANY CRACK.
Xcw=0.000
Xcw=20.000
STRINGERS 11-22  INSPECTION AREA
STRINGER 22
•- STRINGER 21
•- STRINGER 20
- STRINGER 19
' STRINGER 18
• STRINGER 17
• STRINGER 16
STRINGER 15
STRINGER 14
• STRINGER 13
• STRINGER 12
STRINGER 11
- REAR SPAR
- SKIN
STRINGER
LOWER WING SKINS AND STRINGERS
LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE
(VIEW LOOKING DOWN)
INSPECTION AREA  2859026
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Commercial 
Airplanes
MD90
Service Bulletin
ALERT
Number: MD90-57A031
Original Issue: March 19, 2019
ATA System: 5730
SUBJECT: WINGS - Lower Wing Skin - Inspection of Left and Right Center Wing Lower Skins and
Stringers
THIS DOCUMENT 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 DOCUMENT
TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS DOCUMENT TO THE
NEW OWNER.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
This bulletin is applicable to MD-90-30 Airplane(s), line number(s) 2018, 2094-2100, 2115, 2117,
2120, 2122-2123, 2125-2126, 2129, 2131, 2133, 2136, 2138, 2140-2144, 2146-2147, 2149-2150,
2153-2154, 2156-2166, 2168-2173, 2175, 2177, 2179, 2181-2182, 2184, 2186, 2190-2191,
2193-2195, 2197-2198, 2200, 2202-2203, 2205, 2207, 2209-2213, 2215-2217, 2219-2233,
2235-2238, 2240, 2242-2243, 2245-2246, 2248, 2250-2251, 2253, 2255-2263, 2288-2290,
4001-4002 in 1 Group(s). Where the effectivity is presented with hyphens between line numbers,
the airplane applicability means "through" and "inclusive", e.g. line numbers 1-9 means line numbers
1 through 9 inclusive.
This bulletin is applicable to all MD-90-30 Airplanes, line numbers 2018 - 4002 in 1 Group.
The Variable Numbers and Group Information for the applicable airplanes is given below.
DESCRIPTIONCONFIGURATIONGROUP
All MD-90-30 Airplanes, line numbers 2018 - 4002.-1
Airplane Models:
MD-90-30
GroupFuselage Num-
ber
12018
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GroupFuselage Num-
ber
12094 - 2099
12100
12115
12117
12120
12122 - 2123
12125 - 2126
12129
12131
12133
12136
12138
12140 - 2144
12146 - 2147
12149 - 2150
12153 - 2154
12156 - 2166
12168 - 2173
12175
12177
12179
12181 - 2182
12184
12186
12190 - 2191
12193 - 2195
12197 - 2198
12200
12202 - 2203
12205
12207
12209 - 2213
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GroupFuselage Num-
ber
12215 - 2217
12219 - 2233
12235 - 2238
12240
12242 - 2243
12245 - 2246
12248
12250 - 2251
12253
12255 - 2263
12288 - 2290
14001 - 4002
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
Accomplishment of this service bulletin will make sure any crack on the left and right center wing lower
skins and stringers at the fastener holes common to Stringers 11 through 22 and around the external
bracket angle at Stringers 18 and 19 is found. If this service bulletin is not done, undetected fatigue
cracks may result in the inability of the structure to sustain limit loads, which could adversely affect the
structural integrity of the airplane.
The MD-90 center wing stringers and skins have been identified to potentially be susceptible to cracking,
based on MD-80 service experience. MD-80 and MD-90 wings share the same basic design and have
similar stresses. MD-80 operators have reported finding cracks in the center wing lower stringers, lower
stringer end fittings, and lower forward and aft skins. The cracks in stringers occur at the inboard end
where they are joined to the aircraft centerline by end fittings. Cracks in the end fittings occur at the
outboard end where they attach to stringers. The wing skin cracks occur underneath a cracked stringer.
The cause of the cracks has been determined to be from fatigue. The Boeing Company has not received
any reports of cracks on MD90 airplanes.
Boeing Service Related Problem (SRP) MD90-SRP-57-0312 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) MD-90 FTD 57-17001 is related to this service bulletin.
Export Controlled ECCN: 9E991
Copyright © Unpublished
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D. Description
Get access to the left and right center wing lower skins, stringers S-11 thru S-22 between Xcw=0 and
Xcw=20 under the wing/fuselage fillet panels. Do an Eddy Current, Low Frequency (ETLF) inspection
of the left and right side fastener holes common to stringers 11 thru 22 and the forward and aft skins
for any crack and do an Eddy Current, High Frequency (ETHF) inspection of the lower skin at stringers
18 thru 20 for any crack. If any crack is found, contact The Boeing Company for repair instructions and
do the repair; and repeat the inspections for any crack in the unrepaired area. If no crack is found,
repeat the inspections for any crack.
The work in this service bulletin is done in the maintenance zone(s) given below.
Affected Maintenance Zones
ZoneModel
151, 161MD-90-30
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.
Accomplish the required actions, based on the applicable conditions in Table 1, in accordance with
Paragraph 3. Accomplishment Instructions.
When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When
more than one ACTION is given for a CONDITION or an OPTION, do all of the ACTION numbers for
that CONDITION or OPTION.
A logic diagram showing compliance tasks and compliance times is included as an aid in APPENDIX
A.
Table 1: Eddy Current, Low Frequency (ETLF) and Eddy Current, High Frequency (ETHF) Inspections
of Left and Right Center Wing Lower Skins and Stringers
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 3,500
flight cycles after
the original issue
date of this ser-
vice bulletin.
Before 29,000
total flight cycles.
Do an Eddy Current, Low
Frequency (ETLF) inspection
of the left and right side fas-
tener holes common to
stringers 11 thru 22 and the
forward and aft skins for any
crack and do an Eddy Cur-
rent, High Frequency (ETHF)
inspection of the lower skin
at stringers 18 thru 20 for any
crack.
All Airplanes
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Table 1: Eddy Current, Low Frequency (ETLF) and Eddy Current, High Frequency (ETHF) Inspections
of Left and Right Center Wing Lower Skins and Stringers
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.ACTION 1: Contact The Boe-
ing Company for repair in-
structions and do the repair.
CONDITION 1: ANY
CRACK FOUND
3,500 flight cycles.-ACTION 2: Repeat Eddy
Current, Low Frequency
(ETLF) inspection of the left
and right side fastener holes
common to stringers 11 thru
22 and the forward and aft
skins for any crack and do an
Eddy Current, High Frequen-
cy (ETHF) inspection of the
lower skin at stringers 18 thru
20 for any crack in the unre-
paired areas.
3,500 flight cycles.-Repeat Eddy Current, Low
Frequency (ETLF) inspection
of the left and right side fas-
tener holes common to
stringers 11 thru 22 and the
forward and aft skins for any
crack and do an Eddy Cur-
rent, High Frequency (ETHF)
inspection of the lower skin
at stringers 18 thru 20 for any
crack.
CONDITION 2: NO
CRACK FOUND
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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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
Elapsed HoursTask HoursNumber of PersonsTask
FIGURE 1
FIGURE 2
FIGURE 3
TOTAL FOR EACH AIRPLANE
H. Weight and Balance Changes
None.
I. Electrical Load Data
Not changed.
J. References
1. Existing Data:
a. Standard Overhaul Practices Manual (SOPM) 20-50-01
b. MD-90 Aircraft Maintenance Manual (AMM) 06-31-00
c. MD-90 Fleet Team Digest (FTD) 57-17001
d. MD-90 Structural Repair Manual (SRM) 51, 51-20-00, 51-30
2. Data Supplied with this Service Bulletin:
a. Drawings:
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ADCNDCN/REVSheetTitleDrawing No
--10.0INSPECTION - LOWER WING
STRINGERS
SN09570007
--11.0
--12.0
--12.1
--13.1
--3.0
--32.0
--33.0
--34.0
--35.0
--36.0
--37.0
--38.0
--6.0
--7.1
--7.2
--7.3
--8.0
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ADCNDCN/REVSheetTitleDrawing No
-B1.0INSPECTION - LOWER WING
STRINGERS
SN09570007
-A13.0
--14.0
-B14.1
--15.0
--16.0
--17.0
--17.1
-A18.0
-A18.1
--19.0
-B2.0
-B2.1
--20.0
-A21.0
--22.0
--23.0
-A24.0
--25.0
--26.0
--27.0
--28.0
--29.0
--30.0
-B31.0
-B4.0
-B5.0
-A6.1
-B7.0
-B9.0
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3. Installation Drawings Used in the Preparation of this Service Bulletin:
TitleDocument Number
DOOR INSTL - LOWER FORWARD, WING TO FUS FILLET5951288
FILLET INSTL - UNDER WING FORWARD WING TO FUSELAGE5953588
The table above lists applicable drawings used to prepare this service bulletin. The drawings are
not necessary to make the specified changes, and are not supplied with this service bulletin. The
drawings may not be applicable to all airplane configurations or operators.
K. Publications Affected
1. Publications:
None.
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs 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 Fatigue Critical Structures (FCS) but does not
contain repairs or changes.
L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
M. Software Accomplishment Summary
Not affected.
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### Page 19

2.    MATERIAL INFORMATION
A. Material - Price and Availability
The operator can supply the parts and materials shown in Paragraph 2.C., Parts Necessary for Each
Airplane, As an alternative, operators can purchase the parts from Boeing Spares. This service bulletin
does not show the Boeing price and supply data.
B. Industry Support Information
Boeing warranty remedies are not available for the inspection given in this service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
Refer to Boeing drawing SN09570007 given in Paragraph 1.J.2., Data Supplied with this Service
Bulletin.
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 part and material supply to make sure all necessary parts and materials are available.
NotesNameQTYPart Number / Specification
(a)(d)(e)Sealant16 oz.PR-1422B
(b)(c)(d)Sealant16 oz.DMS 1819
(a) This sealant has a dark color and a shorter curing time than DMS 1819 sealant.
(b) This is an aluminized sealant with longer curing time than PR-1422B sealant. It may be used as an alter-
native to PR-1422B.
(c) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data.
(d) Sealant can be purchased from Aviall. Aviall (Cage 22819), 2750 Regent Boulevard, Dallas, Texas 75261
Contact Information: Email: Supplier_Services@Aviall.com, Attention: Product Line Manager, Telephone:
1-800-Aviall-1 or 972-586-1000, Website: http://www.aviall.com
(e) This sealant contains an Octylphenolethoxylate (OPE) and will not be allowed for use in the European
Union after January 2021.
3. Parts Modified and Reidentified
None.
4. Parts Removed and Not Replaced
None.
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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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3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
IF ELECTRICAL POWER IS APPLIED TO THE AIRPLANE, MAKE SURE YOU
OBEY ALL PRECAUTIONS WHILE YOU DO WORK. IF YOU DO NOT OBEY THE
PRECAUTIONS, DEATH OR INJURY TO PERSONS, AND DAMAGE TO THE
AIRPLANE CAN OCCUR.
WARNING
ELECTRICALLY GROUND THE AIRPLANE. THIS WILL HELP TO PREVENT
DAMAGE TO THE AIRPLANE OR EQUIPMENT.
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 BUNDLE
SCAN CAUSE SPARKS OR OTHER ELECTRICAL DAMAGE.
CAUTION
NOTE: 1. The compliance times for the actions in WORK INSTRUCTIONS are in Compliance.
2. Equivalent parts are listed in the AEPL, Drawing 7595071.
3. Use the approved fastener and process material substitutions, in accordance with
MD-90 SRM 51-30, Volume II.
4. If the length of any fastener specified in this service bulletin does not meet installation
standards given in Structural Repair Manual (SRM) Chapter 51, then a fastener of
the same specification, or an approved substitute, with a length which meets the
installation standards given in SRM Chapter 51 may be used. In addition, washers
may be installed for fastener grip length in accordance with SRM Chapter 51. Refer
to SOPM 20-50-01 for alternate full threaded fasteners (screws) needed for installation
in this service bulletin.
5. 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 are in MD-90 SRM 51.
– Torque Values:
– Values for structural fasteners are given in MD-90 Structural Repair Manual,
Chapter 51.
– Values for airframe maintenance tasks are included in Chapter 20 of MD-90
Aircraft Maintenance Manual (AMM).
– Values for electrical maintenance tasks are included in Chapter 20 of
Standard Wiring Practices Manual (SWPM).
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– Values for engine maintenance tasks are included in Chapter 70 of MD-90
Aircraft Maintenance Manual (AMM).
– Non-standard torque values for maintenance tasks are included in the
applicable installation step.
6. When more than one OPTION is given for a CONDITION, do only one of the OPTION
numbers. When more than one ACTION is given for a CONDITION or an OPTION,
do all of the ACTION numbers for that CONDITION or OPTION.
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. 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.
9. Where the work instructions include installation of a kept part, a new or serviceable
part with the same part number can be installed as an alternative to the kept part.
10. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
11. Obey all of the warnings and cautions given in the specified manual sections.
12. Refer to Appendix APPENDIX A for logic diagram. Logic diagrams are provided as
an aid only. Information contained in Paragraph 1.E., Compliance is the primary
source for compliance times. Information contained in Paragraph 3.B., Work
Instructions is the primary source for tasks required for compliance.
13. Use of colors in Figures is based on guidance from the ATA e-Business Program
(ATA) iSpec 2200.
14. Some steps in the Work Instructions are labeled as Required for Compliance (RC).
If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps
labeled as RC, including sub-steps under an RC step and any figures identified in
an RC step, must be done to comply with the AD. If a step or sub-step is labeled
"RC Exempt," then the RC requirement is removed from that step or sub-step. An
Alternative Method of Compliance (AMOC) is required for any deviations to RC steps,
including sub-steps and identified figures. Steps not labeled as RC may be deviated
from using accepted methods in accordance with the operator's maintenance or
inspection program without obtaining approval of an AMOC. This is provided that
the RC steps, including sub-steps and identified figures, can still be done as specified,
and the airplane can be put back in an airworthy condition.
B. WORK INSTRUCTIONS
1. Remove and keep left and right wing/fuselage fillet panels, refer to FIGURE 1 to get access to the
inspection area.
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2. RC - Do an Eddy Current, Low Frequency (ETLF) inspection of the left and right side wing fastener
holes common to stringers 11 thru 22 and the forward and aft skins for any crack and do an Eddy
Current, High Frequency (ETHF) inspection of the lower skin at stringers 18 thru 20 for any crack
in accordance with FIGURE 2.
a. CONDITION 1: ANY CRACK FOUND
(1) Action 1: Contact the Boeing company for the repair instructions and do the repair.
(2) Action 2: Repeat Eddy Current, Low Frequency (ETLF) inspection of the left and right
side wing fastener holes common to stringers 11 thru 22 and the forward and aft skins
for any crack and do an Eddy Current, High Frequency (ETHF) inspection of the lower
skin at stringers 18 thru 20 for any crack in the unrepaired area in accordance with FIGURE
2.
b. CONDITION 2: NO CRACK FOUND
(1) Repeat Eddy Current, Low Frequency (ETLF) inspection of the left and right side wing
fastener holes common to stringers 11 thru 22 and the forward and aft skins for any crack
and do an Eddy Current, High Frequency (ETHF) inspection of the lower skin at stringers
18 thru 20 for any crack in accordance with FIGURE 2.
3. Install the kept win/fuselage fillet panels, refer to FIGURE 3 to close access.
4. Put the airplane back to a serviceable condition.
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FIGURE 1: OPEN ACCESS - CENTER WING LOWER SKIN PANELS
(SHEET 1 OF 3)
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FIGURE 1: OPEN ACCESS - CENTER WING LOWER SKIN PANELS
(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. The QTY
numbers shown below are the number of parts necessary for each airplane.
More DataQtyIdentificationNameTaskStep
Keep all of the fasteners. (a)1150DLPANELRemove / Keep1
Keep all of the fasteners. (a)1150GLPANELRemove / Keep
Keep all of the fasteners. (a)1150KLPANELRemove / Keep
Keep all of the fasteners. (a)1160DRPANELRemove / Keep
Keep all of the fasteners. (a)1160GRPANELRemove / Keep
(a) Refer to MD-90 AMM 06-31-00 as an accepted procedure.
FIGURE 1: OPEN ACCESS - CENTER WING LOWER SKIN PANELS
(SHEET 3 OF 3)
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BOEING SERVICE BULLETIN MD90-57A031
ALERT  ALERT
Xcw=0.000
Xcw=20.000
STRINGER 22 -#
STRINGER 21 -
STRINGER 20 -
STRINGER 19 -
STRINGER 18
STRINGER 17
STRINGER 16
STRINGER 15
17 LOCATIONS
STRINGER 14
STRINGER 13
STRINGER 12
STRINGER 11
REAR SPAR
SKIN-
LOWER WING SKINS AND STRINGERS
LEFT SIDE
(VIEW LOOKING UP)
INSPECTION AREA
2859021
FIGURE 2: INSPECTION - CENTER WING LOWER SKIN - EDDY CURRENT, LOW FREQUENCY (ETLF)
AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS
(SHEET 1 OF 3)
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### Page 28 (OCR)

BOEING SERVICE BULLETIN MD90-57A031
ALERT  ALERT
Xcw=0.000
Xcw=20.000
STRINGER 22
-- STRINGER 21
- STRINGER 20
- STRINGER 19
STRINGER 18
STRINGER 17
STRINGER 16
STRINGER 15
7 LOCATIONS (1
• STRINGER 14
• STRINGER 13
STRINGER 12
STRINGER 11
• REAR SPAR
— SKIN
LOWER WING SKINS AND STRINGERS
RIGHT SIDE
(VIEW LOOKING UP)
INSPECTION AREA
2860798
FIGURE 2: INSPECTION - CENTER WING LOWER SKIN - EDDY CURRENT, LOW FREQUENCY (ETLF)
AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS
(SHEET 2 OF 3)
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### Page 29

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 each airplane.
More DataQtyIdentificationNameTaskStep
(a)--CENTER WING LOW-
ER SKIN/STRINGER
Inspect1
(b)--CENTER WING LOW-
ER SKIN
Inspect2
(a) Do a Eddy Current, Low Frequency (ETLF) Inspection of the left and right center wing lower skins and
stringers for any crack in accordance with Drawing SN09570007 inspection sequence 1.
(b) Do a Eddy Current, High Frequency (ETHF) inspection of the left and right center wing lower skin for any
crack in accordance with Drawing SN09570007 inspection sequence 2.
FIGURE 2: INSPECTION - CENTER WING LOWER SKIN - EDDY CURRENT, LOW FREQUENCY (ETLF)
AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS
(SHEET 3 OF 3)
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FIGURE 3: CLOSE ACCESS - CENTER WING LOWER SKIN PANELS
(SHEET 1 OF 3)
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FIGURE 3: CLOSE ACCESS - CENTER WING LOWER SKIN PANELS
(SHEET 2 OF 3)
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### Page 32

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 each airplane.
More DataQtyIdentificationNameTaskStep
Install with kept fasteners. (a)1150DLPANELInstall (Kept)1
Install with kept fasteners. (a)1150GLPANELInstall (Kept)
Install with kept fasteners. (a)1150KLPANELInstall (Kept)
Install with kept fasteners. (a)1160DRPANELInstall (Kept)
Install with kept fasteners. (a)1160GRPANELInstall (Kept)
(b)-PR-1422B OR DMS 1819SEALANTApply2
(a) Refer to MD-90 AMM 06-31-00 as an accepted procedure.
(b) Apply sealant to the gap on three sides and smooth flush to the surrounding surfaces. Refer to MD-90
SRM 51-20-00, Volume II as an accepted procedure.
FIGURE 3: CLOSE ACCESS - CENTER WING LOWER SKIN PANELS
(SHEET 3 OF 3)
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Logic diagrams are provided as an aid only. Information contained in Paragraph 1.E., Compliance is the primary
source for compliance times. Information contained in Paragraph 3.B., Work Instructions is the primary source
for tasks required for compliance.
1. The table below gives the description for the parts and conditions called out in the logic diagrams.
DescriptionTitle
ANY CRACK FOUND.CONDITION 1
NO CRACK FOUND.CONDITION 2
APPENDIX A:  LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE TABLE 1: EDDY CURRENT, LOW
FREQUENCY (ETLF) AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS OF LEFT AND
RIGHT CENTER WING LOWER SKINS AND STRINGERS
(SHEET 1 OF 2)
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### Page 34 (OCR)

BOEING SERVICE BULLETIN MD90-57A031
ALERT  ALERT
WHICHEVER OCCURS LATER
WITHIN 3,500 FLIGHT
BEFORE 29,000 TOTAL  CYCLES AFTER THE
FLIGHT CYCLES  ORIGINAL ISSUE DATE OF
THIS SERVICE BULLETIN
DO AN EDDY CURRENT, LOW FREQUENCY (ETLF)
INSPECTION OF THE LEFT AND RIGHT SIDE OF
FASTENER HOLES COMMON TO STRINGERS 11
THRU 22 AND THE FORWARD AND AFT SKIN FOR
FRESH AT STINGERS IS THRU FOR AYER
CRACK
CONDITION 1
BEFORE FURTHER
FLIGHT
ACTION 1: CONTACT THE BOEING
COMPANY FOR REPAIR
INSTRUCTIONS AND DO THE
REPAIR
3,500 FLIGHT CYCLES
ACTION 2: REPEAT EDDY CURRENT,
LOW FREQUENCY (ETLF) INSPECTION
OF THE LEFT AND RIGHT SIDE OF
FASTENER HOLES COMMON TO
STRINGERS 11 THRU 22 AND THE
FORWARD AND AFT SKIN FOR ANY
CRACK AND DO AN EDDY CURRENT,
HIGH FREQUENCY (ETHF) INSPECTION
OF THE LOWER SKIN AT STRINGERS 18
THRU 20 FOR ANY CRACK IN THE
UNREPAIRED AREAS
CONDITION 2
3,500 FLIGHT CYCLES
REPEAT EDDY CURRENT, LOW
FREQUENCY (ETLF) INSPECTION OF
THE LEFT AND RIGHT SIDE OF
FASTENER HOLES COMMON TO
STRINGERS 11 THRU 22 AND THE
FORWARD AND AFT SKIN FOR ANY
CRACK AND DO AN EDDY CURRENT,
HIGH FREQUENCY (ETHF) INSPECTION
OF THE LOWER SKIN AT STRINGERS 18
THRU 20 FOR ANY CRACK..
2859172
APPENDIX A: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE TABLE 1: EDDY CURRENT, LOW
FREQUENCY (ETLF) AND EDDY CURRENT, HIGH FREQUENCY (ETHF) INSPECTIONS OF LEFT AND
RIGHT CENTER WING LOWER SKINS AND STRINGERS
(SHEET 2 OF 2)
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