# Boeing Alert Service Bulletin MD90-53A037: No revision named

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- Document: [Boeing Alert Service Bulletin MD90-53A037](https://openairdocs.org/service-documents/boeing/md90-53a037.md)
- Title as filed: SB-MD90-53A037-R00
- Pages: 24
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## Text

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### Page 1

Commercial 
Airplanes
MD90
Service Bulletin
ALERT
Number: MD90-53A037
Original Issue: September 19, 2016
ATA System: 5313
SUBJECT: FUSELAGE - Fuselage, Tail Section - Inspect Cant Station 1520 Bulkhead
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:
BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET
Copyright © 2016 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Unpublished Work.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
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Original Issue: September 19, 2016
MD90-53A037
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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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 14
K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 15
3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 15
3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
FIGURE 1: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD (LEFT SIDE) . . . . . . . . . 20
FIGURE 2: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD (RIGHT SIDE) . . . . . . . . 22
APPENDIX A: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD . . . . . . . . . . . . . . . . 24
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Commercial 
Airplanes
MD90
Service Bulletin
ALERT
SummaryNumber: MD90-53A037Original Issue: September 19, 2016
ATA System: 5313
SUBJECT: FUSELAGE - Fuselage, Tail Section - Inspect Cant Station 1520 Bulkhead
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
An MD-90 operator reported cracking of various structure in the MD-90 fuselage Cant Station 1520 Bulkhead.
The cracking was discovered during scheduled maintenance on an airplane with 52,993 flight-hours, and 28,718
flight cycles. The cracks were in the upper left area of the bulkhead, between Longerons 5 and 10, in the web,
lower tee cap, and the upper cap and (cap) doubler, in the same plane as the vertical stabilizer rear spar. Boeing
analysis has determined that the operational and limit loads cannot duplicate this condition and the root cause
is suspected to be the result of a High Load Event(s) based on service experience. Cracking of the bulkhead,
if undetected, may result in the inability of the structure to sustain limit loads, and could adversely affect the
structural integrity of the airplane.
Boeing Fleet Team Digest (FTD) MD-90 FTD 53-16001 is related to this service bulletin.
Boeing Service Related Problem (SRP) MD90-SRP-53-0531 is related to this service bulletin.
Boeing Communication Systems (BCS) Message Number TBC-DAL-16-0039-01B 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
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
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ReferenceAffectedPlanning Data
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
NoOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION
On the left and right sides at Cant STA 1520 Bulkhead, do a detailed inspection of the forward and aft surfaces,
for any crack in the upper cap, upper (cap) doubler, webs and doublers, stiffeners, and the lower tee cap, between
Longerons 3 through 11.
If any crack is found in the bulkhead web or doubler, do the repair in accordance with MD-90 SRM Volume I,
51-11-01, or MD-90 SRM Volume I, 53-10-03.
If any non-web or non-doubler crack is found in the bulkhead, contact The Boeing Company for repair instructions
and do the repair.
If no crack is found, no further action is required.
EFFECTIVITY
All MD-90-30 Airplane(s). Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplane(s).
COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service
bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin
mandatory.
Refer to Paragraph 1.E., Compliance.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the inspection given in this service bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
None.
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BOEING SERVICE BULLETIN MD90-53A037
ALERT  ALERT
CANT
STA 1520
BULKHEAD
ON THE LEFT AND RIGHT SIDES AT CANT STA 1520
BULKHEAD, DO A DETAILED INSPECTION OF THE FORWARD
AND AFT SURFACES, FOR ANY CRACK IN THE UPPER CAF
THROUGH NERVE CAR. BETWEEN LONGERORSEFENERS.  2531920
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Commercial 
Airplanes
MD90
Service Bulletin
ALERT
Number: MD90-53A037
Original Issue: September 19, 2016
ATA System: 5313
SUBJECT: FUSELAGE - Fuselage, Tail Section - Inspect Cant Station 1520 Bulkhead
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 service bulletin is applicable to all MD-90-30 Airplanes. The line numbers are 2018 through
2290, 4001, and 4002 in 1 Group. The Variable Numbers and Group Information for the applicable
airplanes is given below.
This service bulletin is for the airplanes shown below.
DESCRIPTIONCONFIGURATIONGROUP
All MD-90-30 airplanes.-1
Airplane Models:
MD-90-30
GroupFuselage Num-
ber
12018
12094 - 2099
12100
12115
12117
12120
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GroupFuselage Num-
ber
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
12215 - 2217
12219 - 2233
12235 - 2238
12240
12242 - 2243
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GroupFuselage Num-
ber
12245 - 2246
12248
12250 - 2251
12253
12255 - 2263
12288 - 2290
14001 - 4002
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
An MD-90 operator reported cracking of various structure in the MD-90 fuselage Cant Station 1520
Bulkhead. The cracking was discovered during scheduled maintenance on an airplane with 52,993
flight-hours, and 28,718 flight cycles. The cracks were in the upper left area of the bulkhead, between
Longerons 5 and 10, in the web, lower tee cap, and the upper cap and (cap) doubler, in the same plane
as the vertical stabilizer rear spar. Boeing analysis has determined that the operational and limit loads
cannot duplicate this condition and the root cause is suspected to be the result of a High Load Event(s)
based on service experience. Cracking of the bulkhead, if undetected, may result in the inability of the
structure to sustain limit loads, and could adversely affect the structural integrity of the airplane.
Boeing Fleet Team Digest (FTD) MD-90 FTD 53-16001 is related to this service bulletin.
Boeing Service Related Problem (SRP) MD90-SRP-53-0531 is related to this service bulletin.
Boeing Communication Systems (BCS) Message Number TBC-DAL-16-0039-01B is related to this
service bulletin.
D. Description
On the left and right sides at Cant STA 1520 Bulkhead, do a detailed inspection of the forward and aft
surfaces, for any crack in the upper cap, upper (cap) doubler, webs and doublers, stiffeners, and the
lower tee cap, between Longerons 3 through 11.
If any crack is found in the bulkhead web or doubler, do the repair in accordance with MD-90 SRM
Volume I, 51-11-01, or MD-90 SRM Volume I, 53-10-03.
If any non-web or non-doubler crack is found in the bulkhead, contact The Boeing Company for repair
instructions and do the repair.
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If no crack is found, no further action is required.
The work in this service bulletin is done in the maintenance zone(s) given below.
Affected Maintenance Zones
ZoneModel
311MD-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.
Do the required actions in accordance with Paragraph 3. Accomplishment Instructions.
A logic diagram showing compliance tasks and compliance times is included as an aid in APPENDIX
A.
Table 1: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
-Within 520 flight cycles
or 4 months after the
original issue date of
this service bulletin,
whichever occurs first.
Do PART 1: DETAILED IN-
SPECTION OF CANT STA
1520 BULKHEAD, for any
crack.
All airplanes
-Before further flight.Repair the bulkhead web or
doubler in accordance with MD-
90 SRM Volume I, 51-11-01, or
MD-90 SRM Volume I, 53-10-
03.
CONDITION 1: ANY CRACK
FOUND IN THE BULKHEAD
WEB OR DOUBLER
-Before further flight.Contact The Boeing Company
for repair instructions and do the
repair.
CONDITION 2: ANY NON-WEB
OR NON-DOUBLER CRACK
FOUND IN THE BULKHEAD
--No further action is required.CONDITION 3: 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.
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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
Elapsed HoursTask HoursNumber of PersonsTask
0.500.501Open Access
0.500.501FIGURE 1
0.500.501FIGURE 2
0.500.501Close Access
2.002.00TOTAL 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) 52-12-00
c. MD-90 Fleet Team Digest (FTD) 53-16001
d. MD-90 Structural Repair Manual (SRM) Chapter 51, Volume I, 51-11-01, Volume I, 53-10-03
e. Boeing Communication Systems (BCS) Message Number TBC-DAL-16-0039-01B
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2. Data Supplied with this Service Bulletin:
None.
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.
M. Software Accomplishment Summary
Not affected.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
None.
B. Industry Support Information
Boeing warranty remedies are not available for the inspections given in this service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
No special parts or materials are necessary to do the change in this service bulletin. But, parts
and materials in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator part and material supply to make sure all necessary parts and materials are available.
3. Parts Modified and Reidentified
None.
4. Parts Removed and Not Replaced
None.
D. Parts Necessary to Change Spares
None.
E. Special Tooling - Price and Availability
None.
F. Special Tooling Necessary to do this Service Bulletin
No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance
and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator tool supply to make sure all necessary tools are available.
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3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
WARNING: WHILE YOU DO WORK IN THE TAILCONE AREA, MAKE SURE THAT YOU OBEY
ALL SAFETY PRECAUTIONS. IF YOU DO NOT OBEY THE PRECAUTIONS, DEATH
OR INJURY TO PERSONS CAN OCCUR.
WARNING: 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.
CAUTION: 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 BUNDLES CAN CAUSE SPARKS OR
OTHER ELECTRICAL DAMAGE.
NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
2. Equivalent parts are listed in the AEPL, Drawing 7595071.
3. Use the approved fastener and process material substitutions, in accordance with
MD-90 SRM Chapter 51.
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. A 1/8-inch thick stack of the same type washers called for in this service bulletin is
the maximum thickness which may be used under fastener head or nut to counteract
accumulation of tolerances.
EXCEPTION: When the available fastener length increments are greater than
1/16-inch, a 3/16-inch thick stack of the same type washers may be used.
6. 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 Chapter 51
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– 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).
— 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.
7. Obey all of the warnings and cautions given in the specified manual sections.
8. 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.
9. 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.
10. Refer to APPENDIX A for logic diagram(s). Logic diagrams are provided as an aid
only. Information contained in Paragraph 1.E., Compliance is the primary source for
compliance times. Information in Paragraph 3.B., Work Instructions is the primary
source for tasks required for compliance.
11. 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.
12. Use of colors in Figures is based on guidance from the ATA e-Business Program
(ATA) iSpec 2200.
13. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS
are in Paragraph 1.E., Compliance.
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,
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BOEING SERVICE BULLETIN MD90-53A037
ALERTALERT

### Page 19

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. Open access to the inspection area through the aft entrance door. Refer to MD-90 AMM 52-12-00,
as an accepted procedure.
2. RC - Do PART 1: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD, for any crack.
a. CONDITION 1: ANY CRACK FOUND IN THE BULKHEAD WEB OR DOUBLER
(1) Repair the bulkhead web or doubler in accordance with MD-90 SRM Volume I, 51-11-01,
or MD-90 SRM Volume I, 53-10-03.
b. CONDITION 2: ANY NON-WEB OR NON-DOUBLER CRACK FOUND IN THE BULKHEAD
(1) Contact The Boeing Company for repair instructions and do the repair.
c. CONDITION 3: NO CRACK FOUND
(1) No further action is required.
3. Close access to the inspection area through the aft entrance door. Refer to MD-90 AMM 52-12-00,
as an accepted procedure.
4. Put the airplane back to a serviceable condition.
PART 1: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD
1. Do a detailed inspection of left side Cant STA 1520 Bulkhead, in accordance with FIGURE 1.
2. Do a detailed inspection of right side Cant STA 1520 Bulkhead, in accordance with FIGURE 2.
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ALERTALERT

### Page 20 (OCR)

BOEING SERVICE BULLETIN MD90-53A037
ALERT  ALERT
CANT
STA 1520
BULKHEAD
L-5L
L-9L
L-11L
INBD
A-A  2531951
FIGURE 1: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD (LEFT SIDE)
(SHEET 1 OF 2)
Original Issue: September 19, 2016
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### Page 21

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 figure.
More DataQtyIdentificationNameTaskStep
(a)19953015-67CAPInspect1
(a)19953015-69DOUBLERInspect2
(a)19911958-503CAPInspect3
(a)19953015-107WEBInspect4
(a)19953015-37DOUBLERInspect5
(a)19953015-57WEBInspect6
(a) Do a detailed inspection of the left side Cant STA 1520 Bulkhead, forward and aft surfaces, for any crack
in the upper cap, upper (cap) doubler, bulkhead webs and doublers, stiffeners, and the lower tee cap,
between Longerons 3L through 11L.
FIGURE 1: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD (LEFT SIDE)
(SHEET 2 OF 2)
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BOEING SERVICE BULLETIN MD90-53A037
ALERTALERT

### Page 22 (OCR)

BOEING SERVICE BULLETIN MD90-53A037
ALERT  ALERT
CANT
STA 1520
BULKHEAD
_-5R
.-7R
,L-9R
L-11R
A-A  2532128
FIGURE 2: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD (RIGHT SIDE)
(SHEET 1 OF 2)
Original Issue: September 19, 2016
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Work - See page 1 for details.

### Page 23

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 figure.
More DataQtyIdentificationNameTaskStep
(a)19953015-67CAPInspect1
(a)19953015-69DOUBLERInspect2
(a)19911958-503CAPInspect3
(a)19953015-107WEBInspect4
(a)19953015-38DOUBLERInspect5
(a)19953015-58WEBInspect6
(a) Do a detailed inspection of the right side Cant STA 1520 Bulkhead, forward and aft surfaces, for any crack
in the upper cap, upper (cap) doubler, bulkhead webs and doublers, stiffeners, and the lower tee cap,
between Longerons 3R through 11R.
FIGURE 2: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD (RIGHT SIDE)
(SHEET 2 OF 2)
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BOEING SERVICE BULLETIN MD90-53A037
ALERTALERT

### Page 24 (OCR)

BOEING SERVICE BULLETIN MD90-53A037
ALERT  ALERT
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.
Title  Description
PART 1  DETAILED INSPECTION OF CANT STA 1520 BULKHEAD
CONDITION 1  ANY CRACK FOUND IN THE BULKHEAD WEB OR DOUBLER
CONDITION 2  ANY NON-WEB OR NON-DOUBLER CRACK FOUND IN THE BULKHEAD
CONDITION 3  NO CRACK FOUND
WITHIN 520 FLIGHT CYCLES OR 4 MONTHS AFTER
THE ORIGINAL ISSUE DATE OF THIS SERVICE
BULLETIN, WHICHEVER OCCURS FIRST
DO PART 1
CONDITION 1  CONDITION 2  CONDITION 3
BEFORE FURTHER  BEFORE FURTHER
FLIGHT  FLIGHT
REPAIR THE BULKHEAD WEB
OR DOUBLER IN ACCORDANCE  WITH MD-90 SRM VOLUME I,  NO FURTHER ACTION IS
51-11-01 OR MD-90 SRM  REQUIRED
VOLUME 1, 53-10-03
CONTACT THE BOEING COMPANY FOR
REPAIR INSTRUCTIONS AND DO THE REPAIR
APPENDIX A: DETAILED INSPECTION OF CANT STA 1520 BULKHEAD
(SHEET 1 OF 1)
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