# Boeing Alert Service Bulletin MD90-55A018: No revision named

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### Page 1

Commercial 
Airplanes
MD90
Service Bulletin
ALERT
Number: MD90-55A018
Original Issue: June 29, 2016
ATA System: 5510
SUBJECT: STABILIZERS - Horizontal Stabilizer - Rear Spar Upper Cap Inspection, Repair, and
Replacement
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Unpublished Work.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
Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in
connection with this document unless provided in writing by Boeing.
Original Issue: June 29, 2016
MD90-55A018
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3.0

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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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 19
K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 26
3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 28
3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
FIGURE 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY
CURRENT HIGH FREQUENCY (ETHF) INSPECTION . . . . . . . . . . . . . . . . . . . 36
FIGURE 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY
CURRENT HIGH FREQUENCY (ETHF) INSPECTION . . . . . . . . . . . . . . . . . . . 38
FIGURE 3: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP SURFACE EDDY CURRENT
LOW FREQUENCY (ETLF) INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . 40
FIGURE 4: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP SURFACE EDDY
CURRENT LOW FREQUENCY (ETLF) INSPECTION . . . . . . . . . . . . . . . . . . . . 42
APPENDIX A: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 1: LEFT SIDE HORIZONTAL
STABILIZER REAR SPAR UPPER CAP - OPEN HOLE ETHF OR SURFACE ETLF INSPECTION
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
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APPENDIX B: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 2: RIGHT SIDE HORIZONTAL
STABILIZER REAR SPAR UPPER CAP - OPEN HOLE ETHF OR SURFACE ETLF INSPECTION
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
APPENDIX C: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 3: POST LEFT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIR OR REPLACEMENT
- OPEN HOLE ETHF OR SURFACE ETLF INSPECTION . . . . . . . . . . . . . . . . . . 48
APPENDIX D: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 4: POST RIGHT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIR OR REPLACEMENT
- OPEN HOLE ETHF OR SURFACE ETLF INSPECTION . . . . . . . . . . . . . . . . . . 50
APPENDIX E: SIGNAL INDICATIONS FOR AUTOMATED SCAN PROCEDURES . . . . . . . . . . . . 52
APPENDIX F: PART DEMAND INTENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
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Commercial 
Airplanes
MD90
Service Bulletin
ALERT
SummaryNumber: MD90-55A018Original Issue: June 29, 2016
ATA System: 5510
SUBJECT: STABILIZERS - Horizontal Stabilizer - Rear Spar Upper Cap Inspection, Repair, and
Replacement
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
This service bulletin gives instructions to inspect for cracking in the horizontal stabilizer rear spar upper cap
fastener hole at station XE = +/-5.931 and gives subsequent corrective action if any crack is found. If this service
bulletin is not done, such cracks can grow to critical length before being found and could adversely affect the
structural integrity of the airplane.
Service Bulletin MD90-55A012 does an inspection for cracks in the horizontal stabilizer rear spar upper cap
fastener hole at station XE = +/-5.931, but only as a conditional inspection to cracks being found in the upper
aft skin panels. Therefore, it is not guaranteed that cracks in the fastener holes at station XE = +/-5.931 are
detected before they reach critical length. There has been one report of cracking in an MD-90 horizontal stabilizer
rear spar cap at this location. The cause of the cracking is due to fatigue. The affected airplane had accumulated
36,588 flight-hours and 24,975 landing cycles.
Boeing Service Related Problem (SRP) MD90-SRP-55-0067 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) MD-90 FTD 55-07001 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 ChangesYesWeight and Balance Change
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ReferenceAffectedPlanning Data
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedYesPublications 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/PartsYesKits/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
Do an open hole Eddy Current High Frequency (ETHF) or surface Eddy Current Low Frequency (ETLF) inspection
for any crack in the left and right side horizontal stabilizer rear spar upper caps common to the elevator hinge
fitting at XE = +/-5.931. If no crack is found, repeat open hole ETHF or surface ETLF inspection for any crack.
If any crack is found, do a horizontal stabilizer rear spar upper cap splice repair or replacement.
EFFECTIVITY
All MD-90-30 Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes.
COMPLIANCE
Federal Aviation Administration (FAA) Airworthiness Directives AD 2009-13-08 and AD 2014-24-03 are related
to this service bulletin. The effective date of AD 2009-13-08 is August 3, 2009. The effective date of AD 2014-24-03
is January 27, 2015.
The Federal Aviation Administration (FAA) will possibly release an additional 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 inspections and/or repair procedures given in this service
bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
Boeing Supplied Kits/Parts.
Refer to Paragraph 2.A., Material - Price and Availability.
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Operators are encouraged to complete the survey provided in APPENDIX F of this service bulletin to help Boeing
predict the quantity and timing of the Boeing Supplied Kits/Parts.
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Commercial 
Airplanes
MD90
Service Bulletin
ALERT
Number: MD90-55A018
Original Issue: June 29, 2016
ATA System: 5510
SUBJECT: STABILIZERS - Horizontal Stabilizer - Rear Spar Upper Cap Inspection, Repair, and
Replacement
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 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
12122 - 2123
12125 - 2126
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GroupFuselage Num-
ber
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
12245 - 2246
12248
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GroupFuselage Num-
ber
12250 - 2251
12253
12255 - 2263
12288 - 2290
14001 - 4002
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
This service bulletin gives instructions to inspect for cracking in the horizontal stabilizer rear spar upper
cap fastener hole at station XE = +/-5.931 and gives subsequent corrective action if any crack is found.
If this service bulletin is not done, such cracks can grow to critical length before being found and could
adversely affect the structural integrity of the airplane.
Service Bulletin MD90-55A012 does an inspection for cracks in the horizontal stabilizer rear spar upper
cap fastener hole at station XE = +/-5.931, but only as a conditional inspection to cracks being found
in the upper aft skin panels. Therefore, it is not guaranteed that cracks in the fastener holes at station
XE = +/-5.931 are detected before they reach critical length. There has been one report of cracking in
an MD-90 horizontal stabilizer rear spar cap at this location. The cause of the cracking is due to fatigue.
The affected airplane had accumulated 36,588 flight-hours and 24,975 landing cycles.
Boeing Service Related Problem (SRP) MD90-SRP-55-0067 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) MD-90 FTD 55-07001 is related to this service bulletin.
D. Description
Do an open hole Eddy Current High Frequency (ETHF) or surface Eddy Current Low Frequency (ETLF)
inspection for any crack in the left and right side horizontal stabilizer rear spar upper caps common to
the elevator hinge fitting at XE = +/-5.931. If no crack is found, repeat open hole ETHF or surface ETLF
inspection for any crack. If any crack is found, do a horizontal stabilizer rear spar upper cap splice
repair or replacement.
The work in this service bulletin is done in the maintenance zone(s) given below.
Affected Maintenance Zones
ZoneModel
333, 343MD-90-30
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### Page 12

E. Compliance
Federal Aviation Administration (FAA) Airworthiness Directives AD 2009-13-08 and AD 2014-24-03
are related to this service bulletin. The effective date of AD 2009-13-08 is August 3, 2009. The effective
date of AD 2014-24-03 is January 27, 2015.
The Federal Aviation Administration (FAA) will possibly release an additional 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.
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 number or an OPTION number, do all of the ACTION
numbers for that CONDITION number or OPTION number.
Logic diagrams showing compliance tasks and compliance times are included as an aid in APPENDIX
A through APPENDIX D.
The table that follows immediately below describes the service bulletin PARTS noted in the compliance
table.
DescriptionTitle
LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY
CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY CURRENT LOW FRE-
QUENCY (ETLF) INSPECTION
PART 1
RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY
CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY CURRENT LOW FRE-
QUENCY (ETLF) INSPECTION
PART 2
Table 1: Left Side Horizontal Stabilizer Rear Spar Upper Cap - Open Hole ETHF or Surface ETLF Inspection
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,050
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 20,000
total flight cy-
cles.
Do PART 1, OPTION 1:
OPEN HOLE ETHF IN-
SPECTION or OPTION
2: SURFACE ETLF IN-
SPECTION for any crack.
All Airplanes
--Before further
flight.
OPTION 3:
Do a horizontal stabilizer
rear spar upper cap
splice repair. (a)
CONDITION 1: ANY
CRACK FOUND
--Before further
flight.
OPTION 4:
Do a horizontal stabilizer
rear spar upper cap re-
placement. (a)
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Table 1: Left Side Horizontal Stabilizer Rear Spar Upper Cap - Open Hole ETHF or Surface ETLF Inspection
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
3,395 flight cycles.--Do PART 1, OPTION 1:
OPEN HOLE ETHF IN-
SPECTION for any crack.
(b)
CONDITION 2: NO
CRACK FOUND DURING
OPTION 1: OPEN HOLE
ETHF INSPECTION
833 flight cycles.--Do PART 1, OPTION 2:
SURFACE ETLF INSPEC-
TION for any crack. (b)
CONDITION 3: NO
CRACK FOUND DURING
OPTION 2: SURFACE
ETLF INSPECTION
(a) Refer to Table 3 for post left side horizontal stabilizer rear spar upper cap splice repair or replacement
inspection requirements.
(b) It is acceptable to change the repeat inspection method from Option 1 to Option 2 or from Option 2 to
Option 1 provided the repeat interval for the previously accomplished inspection method is complied with.
Table 2: Right Side Horizontal Stabilizer Rear Spar Upper Cap - Open Hole ETHF or Surface ETLF Inspec-
tion
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,050
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 20,000
total flight cy-
cles.
Do PART 2, OPTION 5:
OPEN HOLE ETHF IN-
SPECTION or OPTION
6: SURFACE ETLF IN-
SPECTION for any crack.
All Airplanes
--Before further
flight.
OPTION 7:
Do a horizontal stabilizer
rear spar upper cap
splice repair. (a)
CONDITION 4: ANY
CRACK FOUND
--Before further
flight.
OPTION 8:
Do a horizontal stabilizer
rear spar upper cap re-
placement. (a)
3,395 flight cycles.--Do PART 2, OPTION 5:
OPEN HOLE ETHF IN-
SPECTION for any crack.
(b)
CONDITION 5: NO
CRACK FOUND DURING
OPTION 5: OPEN HOLE
ETHF INSPECTION
833 flight cycles.--Do PART 2, OPTION 6:
SURFACE ETLF INSPEC-
TION for any crack. (b)
CONDITION 6: NO
CRACK FOUND DURING
OPTION 6: SURFACE
ETLF INSPECTION
(a) Refer to Table 4 for post right side horizontal stabilizer rear spar upper cap splice repair or replacement
inspection requirements.
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### Page 14

Table 2: Right Side Horizontal Stabilizer Rear Spar Upper Cap - Open Hole ETHF or Surface ETLF Inspec-
tion
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
(b) It is acceptable to change the repeat inspection method from Option 5 to Option 6 or from Option 6 to
Option 5 provided the repeat interval for the previously accomplished inspection method is complied with.
Table 3: Post Left Side Horizontal Stabilizer Rear Spar Upper Cap Splice Repair or Replacement
- Open Hole ETHF or Surface ETLF Inspection
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
-Within 20,000 flight
cycles after doing
the left side hori-
zontal stabilizer
rear spar upper
cap splice repair or
replacement.
Do PART 1, OPTION 1:
OPEN HOLE ETHF IN-
SPECTION or OPTION
2: SURFACE ETLF IN-
SPECTION for any crack.
Airplanes that have done a
left side horizontal stabiliz-
er rear spar upper cap
splice repair or replace-
ment
-Before further
flight.
OPTION 3:
Do a horizontal stabilizer
rear spar upper cap
splice repair. (a)
CONDITION 1: ANY
CRACK FOUND
-Before further
flight.
OPTION 4:
Do a horizontal stabilizer
rear spar upper cap re-
placement. (a)
3,395 flight cycles.-Do PART 1, OPTION 1:
OPEN HOLE ETHF IN-
SPECTION for any crack.
(b)
CONDITION 2: NO
CRACK FOUND DURING
OPTION 1: OPEN HOLE
ETHF INSPECTION
833 flight cycles.-Do PART 1, OPTION 2:
SURFACE ETLF INSPEC-
TION for any crack. (b)
CONDITION 3: NO
CRACK FOUND DURING
OPTION 2: SURFACE
ETLF INSPECTION
(a) Refer to Table 3 for post left side horizontal stabilizer rear spar upper cap splice repair or
replacement inspection requirements.
(b) It is acceptable to change the repeat inspection method from Option 1 to Option 2 or from
Option 2 to Option 1 provided the repeat interval for the previously accomplished inspection
method is complied with.
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Table 4: Post Right Side Horizontal Stabilizer Rear Spar Upper Cap Splice Repair or Replacement
- Open Hole ETHF or Surface ETLF Inspection
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
-Within 20,000 flight
cycles after doing
the right side hori-
zontal stabilizer
rear spar upper
cap splice repair or
replacement.
Do PART 2, OPTION 5:
OPEN HOLE ETHF IN-
SPECTION or OPTION
6: SURFACE ETLF IN-
SPECTION for any crack.
Airplanes that have done a
right side horizontal stabiliz-
er rear spar upper cap
splice repair or replace-
ment
-Before further
flight.
OPTION 7:
Do a horizontal stabilizer
rear spar upper cap
splice repair. (a)
CONDITION 4: ANY
CRACK FOUND
-Before further
flight.
OPTION 8:
Do a horizontal stabilizer
rear spar upper cap re-
placement. (a)
3,395 flight cycles.-Do PART 2, OPTION 5:
OPEN HOLE ETHF IN-
SPECTION for any crack.
(b)
CONDITION 5: NO
CRACK FOUND DURING
OPTION 5: OPEN HOLE
ETHF INSPECTION
833 flight cycles.-Do PART 2, OPTION 6:
SURFACE ETLF INSPEC-
TION for any crack. (b)
CONDITION 6: NO
CRACK FOUND DURING
OPTION 6: SURFACE
ETLF INSPECTION
(a) Refer to Table 4 for post right side horizontal stabilizer rear spar upper cap splice repair
or replacement inspection requirements.
(b) It is acceptable to change the repeat inspection method from Option 5 to Option 6 or from
Option 6 to Option 5 provided the repeat interval for the previously accomplished inspection
method is complied with.
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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In addition, the Manager of the FAA Los Angeles Aircraft Certification Office approves the action (i.e.
inspection or modification) defined in this service bulletin as an alternative method of compliance to
the requirements of paragraph (g) of AD 2009-13-08 and paragraph (l) of AD 2014-24-03. All provisions
of AD 2009-13-08 and AD 2014-24-03 that are not specifically referenced in the above statement
remain fully applicable and must be complied with.
G. Manpower
The tables below show an estimate of the task hours necessary to do the inspection, rear spar upper
cap replacement, and rear spar upper cap splice repair for each side of the horizontal stabilizer. 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.
Horizontal Stabilizer Rear Spar Upper Cap Eddy Current High Frequency (ETHF) Inspection
Elapsed HoursTask HoursNumber of PersonsTask
0.50.51Access
6.06.01Inspection
0.30.31Install and Lockwire
Drilled Head Bolt
0.50.51Close Access
7.37.3TOTAL FOR EACH SIDE OF THE HORIZON-
TAL STABILIZER
Horizontal Stabilizer Rear Spar Upper Cap Eddy Current Low Frequency (ETLF) Inspection
Elapsed HoursTask HoursNumber of PersonsTask
1.01.01Inspection
1.01.0TOTAL FOR EACH SIDE OF THE HORIZON-
TAL STABILIZER
CONDITION 1, OPTION 3; CONDITION 4, OPTION 7 - Horizontal Stabilizer Rear Spar Upper
Cap Splice Repair
Elapsed HoursTask HoursNumber of PersonsTask
8.048.06Remove - Horizontal
Stabilizer
8.016.02Remove - Elevators
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CONDITION 1, OPTION 3; CONDITION 4, OPTION 7 - Horizontal Stabilizer Rear Spar Upper
Cap Splice Repair
Elapsed HoursTask HoursNumber of PersonsTask
6.012.02Remove - Leading
Edge
72.0216.03Install - Horizontal
Stabilizer Rear Spar
Upper Cap Splice
Repair
6.012.02Install - Leading
Edge
8.016.02Install - Elevators
8.048.06Install - Horizontal
Stabilizer
116.0368.0TOTAL FOR EACH SIDE OF THE HORIZON-
TAL STABILIZER
CONDITION 1, OPTION 4; CONDITION 4, OPTION 8 - Horizontal Stabilizer Rear Spar Upper
Cap Replacement
Elapsed HoursTask HoursNumber of PersonsTask
8.048.06Remove - Horizontal
Stabilizer
8.016.02Remove - Elevators
6.012.02Remove - Leading
Edge
72.0216.03Replace - Horizontal
Stabilizer Rear Spar
Upper Cap
6.012.02Install - Leading
Edge
8.016.02Install - Elevators
8.048.06Install - Horizontal
Stabilizer
116.0368.0TOTAL FOR EACH SIDE OF THE HORIZON-
TAL STABILIZER
H. Weight and Balance Changes
CONDITION 1, OPTION 3; CONDITION 4, OPTION 7 - Horizontal Stabilizer Rear Spar Upper Cap
Splice Repair:
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Moment Change
(MEW) IN.-LBS
Mfr's Empty
Weight (MEW)
LBS
Approximate Sta-
tion (Inches)Airplane
3110.61.81728.1Left OR Right Side
of the Horizontal
Stabilizer
6221.23.61728.1Left AND Right
Side of the Horizon-
tal Stabilizer
CONDITION 1, OPTION 4; CONDITION 4, OPTION 8 - Horizontal Stabilizer Rear Spar Upper Cap
Replacement:
None.
I. Electrical Load Data
Not changed.
J. References
1. Existing Data:
a. Boeing Service Bulletin MD90-55A012
b. Boeing Service Related Problem (SRP) MD90-SRP-55-0067
c. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2009-13-08, 2014-24-03
d. Non-Destructive Test Standard Practices Manual (NDTSPM) 06-00-07, 06-10-01.003
e. MD-90 Aircraft Maintenance Manual (AMM) 06-33-00, 27-30-02, 55-10-01, 55-12-01
f. MD-90 Airworthiness Limitations Instructions (ALI) Document MDC-94K9000 MD-90 ALI
g. MD-90 Fleet Team Digest (FTD) 55-07001
2. Data Supplied with this Service Bulletin:
No data is supplied with this service bulletin.
a. Drawings:
ADCNDCN/REVSheetTitleDrawing No
-BDWGCAP REPLACEMENT - REAR SPAR,
HORIZ STAB
SR90550002
-BDWGCAP SPLICE - REAR UPPER SPAR,
HORIZ STAB
SR90550003
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3. Installation Drawings Used in the Preparation of this Service Bulletin:
None.
K. Publications Affected
1. Publications:
Chapter-SectionPublication
55-10Illustrated Parts Catalog
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. DTI requirements for the structure affected
are contained in Paragraph 1.E., Compliance of this service bulletin.
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 21

2.    MATERIAL INFORMATION
A. Material - Price and Availability
Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary for Each Airplane. Operators
are encouraged to share schedule requirements with Boeing for incorporation of the service bulletin.
The kits are subject to the terms and conditions of the Boeing standard purchase order acknowledgment.
Prices are in United States Dollars. Terms: Net 30 days.
Reference this service bulletin and submit your purchase order by one of these methods:
1. Order on-line via ATA Spec 2000 or The Boeing PART Page
2. Fax to (206) 662-7145
REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST RESPONDER
AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE INFORMATION
Unit Price as of
the original issue
date of this Ser-
vice Bulletin (US
Dollars)
ROLT as of the
original issue
date of this Ser-
vice Bulletin (Cal-
endar Days)
NameKit Number
44,065.0090SERVICE KIT - SPAR SPLICE LFT SIDESA90550018-3
44,065.0090SERVICE KIT - SPAR SPLICE RT SIDESA90550018-5
64,306.0090SERVICE KIT - LFT SPAR REPLACEMENTSA90550018-7
64,306.0090SERVICE KIT - RT SPAR REPLACEMENTSA90550018-9
Operators are encouraged to complete the survey provided in APPENDIX F of this service bulletin to
help Boeing predict the quantity and timing of the Boeing Supplied Kits/Parts.
B. Industry Support Information
Boeing warranty remedies are not available for the inspections and/or repair procedures given in this
service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts
To get the kits/parts shown below, refer to Paragraph 2.A., Material - Price and Availability.
NOTE: One service kit and the items shown in Paragraph 2.C.2., Parts and Materials Supplied
by the Operator, are necessary for each side of the horizontal stabilizer as a result of
inspection findings.
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Service Kits should be ordered as follows:
Service Kit RequiredCondition, Option
SA90550018-3CONDITION 1, OPTION 3
SA90550018-5CONDITION 4, OPTION 7
SA90550018-7CONDITION 1, OPTION 4
SA90550018-9CONDITION 4, OPTION 8
Kit SA90550018
NotesExisting Part
Number
NameQTYNew Part Number
-9-7-5-3
NUT22..113LH7940T064
NUT5522113LH7940T070
BARREL NUT7722113LH7940T080
FILLER44443964835-507
(a) (b)NUT ASSY1881881561563D0006-3
(a)NUT ASSY22223D0006-4
(a)BARREL NUT22223D0011-9
(a)RETAINER22223D0012-9
(a)BOLT22223D0031-9-34
(a)NUT11..3D0043-5
WASHER222273232-9-28.7
HI LOCK11..HL327-6-10
PIN22..HL328-6-10
PIN22..HLT435-6-3
(b)PIN70704343HLT435-6-4
(b)PIN62621919HLT435-6-5
PIN3333HLT435-6-6
PIN..66HLT435-6-7
PIN..1111HLT435-6-8
PIN10101818HLT435-6-9
PIN..33HLT435-6-10
PIN..77HLT435-6-11
PIN33..HLT436-6-3
(b)PIN595966HLT436-6-4
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Kit SA90550018
NotesExisting Part
Number
NameQTYNew Part Number
-9-7-5-3
(b)PIN343466HLT436-6-5
PIN19191616HLT436-6-6
PIN9922HLT436-6-7
PIN232322HLT436-6-8
PIN882424HLT436-6-9
PIN12121212HLT436-6-10
PIN..44HLT436-6-11
PIN8888HLT436-6-12
PIN14141414HLT436-6-13
PIN10101010HLT436-6-15
PIN4444HLT436-6-16
PIN4444HLT436-6-20
PIN4444HLT436-6-21
PIN22..HLT436-8-6
PIN11..HLT436-8-8
PIN2222HLT436-8-21
PIN33..HLT439-6-4
PIN22..HLT439-6-5
PIN3311HLT439-6-6
PIN22..HLT439-6-7
WASHER11..MS20002-5
WASHER11..MS20002C5
WASHER22..MS20002C6
WASHER5522MS20002C7
WASHER6611MS20002C8
RIVET22..MS20426AD3-4D
(b)RIVET4646..MS20426AD5-7D
RIVET2020..MS20426AD6-7D
(b)RIVET136136..MS20426AD6-8D
RIVET2222MS20426AD6-11D
RIVET1212..MS20470AD5-6D
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Kit SA90550018
NotesExisting Part
Number
NameQTYNew Part Number
-9-7-5-3
RIVET1212..MS20470AD5-7D
RIVET..44MS20470AD6-8D
(b)RIVET4545..MS20470E5-6D
RIVET1717..MS20470E5-7D
RIVET11..MS20470E5-8D
RIVET1717..MS20470E6-7D
RIVET2222..MS20470E6-8D
(b)NUT2282287777MS21042L3
NUT33..MS21042L4
NUTPLATE11..MS21075L3
BLIND FASTENER1111MS21140U0604P
BOLT11..MS21250-05018
BOLT11..MS21250-06020
BOLT11..MS21250-06022
BOLT11..MS21250-07020
BOLT11..MS21250-07024
BOLT11..MS21250-07026
BOLT1111MS21250-07028
BOLT1111MS21250-07036
BOLT6611MS21250-08028
RIVET88..NAS1097KE5-6D
RIVET44..NAS1097KE5-7D
(b)RIVET5151..NAS1097KE6-8D
(b)RIVET5252..NAS1097KE6-9D
RIVET44..NAS1097KE8-10D
WASHER272755NAS1149F0332P
(b)WASHER2282286767NAS1252-10L
WASHER33..NAS1252-416L
RADIUS WASHER3366NAS1401-3D3
WASHER..1010NAS1401-3D5
SCREW1010..NAS1403-4
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Kit SA90550018
NotesExisting Part
Number
NameQTYNew Part Number
-9-7-5-3
SCREW55..NAS1403-5
SCREW55..NAS1403-6
SCREW5555NAS1403-7
SCREW22..NAS1403-9
WASHER2121..NAS1587-4C
SCREW11..NAS333CPA4-5
RETAINER22..NAS578-6B
RETAINER5522NAS578-7B
RETAINER7722NAS578-8B
BOLT11..PIC239-3-3
BOLT11..PIC239-4-4
BOLT11..PIC239-4-5
(a)PIN22..S4931917-6-5
(a)PIN55..S4931919-6-3
(a)PIN11..S4931919-6-4
(a)PIN3322S4931919-6-5
(a)PIN88..S4931920-6-4
(a)PIN88..S4931920-6-5
(a)PIN101022S4931920-6-6
(a)PIN4444S4931920-6-7
(a)PIN11..S4931920-6-8
(a)PIN55..S4931920-6-10
DOUBLER...1SR09550027-7
DOUBLER..1.SR09550027-8
SPACER..11SR09550027-9
SPACER..11SR09550027-11
SPACER..11SR09550027-19
(c)ANGLE...1SR09550027-27
(d)ANGLE..1.SR09550027-28
(e)ANGLE...1SR09550027-29
(f)ANGLE..1.SR09550027-30
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Kit SA90550018
NotesExisting Part
Number
NameQTYNew Part Number
-9-7-5-3
ANGLE..11SR09550027-31
(g)SPAR CAP.1..SR90550002-3
(h)SPAR CAP1...SR90550002-4
(i)CAP...1SR90550003-3
(j)CAP..1.SR90550003-4
(a) Or approved equivalent. Refer to AEPL Drawing 7595071.
(b) Noted QTY is approximate.
(c) SR09550027-3 is an alternate part for SR09550027-27 if a minimum of 2D edge distance
can be maintained at both ends of the alternate part.
(d) SR09550027-4 is an alternate part for SR09550027-28 if a minimum of 2D edge distance
can be maintained at both ends of the alternate part.
(e) SR09550027-5 is an alternate part for SR09550027-29 if a minimum of 2D edge distance
can be maintained at both ends of the alternate part.
(f) SR09550027-6 is an alternate part for SR09550027-30 if a minimum of 2D edge distance
can be maintained at both ends of the alternate part.
(g) 5918000-534 is an alternate part for SR90550002-3 for configuration noted if a minimum of
2D edge distance on all fasteners is maintained and any trimming on inbd end of part is
within B/P tolerance.
(h) 5918000-533 is an alternate part for SR90550002-4 for configuration noted if a minimum of
2D edge distance on all fasteners is maintained and any trimming on inbd end of part is
within B/P tolerance.
(i) SR09550027-21 is an alternate part for SR90550003-3 for configuration noted.
(j) SR09550027-22 is an alternate part for SR90550003-4 for configuration noted.
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 part and material supply to make sure all necessary parts and materials are available.
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NotesExisting Part NumberNameQTYPart Number /
Specification
(a) (b)-SealantAs Re-
quired
PR-1422 Class B-
2 (DMS 2082
Class B-2)
OR
PR-1422 Class B-
6 (DPM 2292-6)
OR
P/S870C-24/80
(DMS 2013 Type
2, Class A)
OR
P/S870C-48/168
(DMS 2013 Type
4, Class A)
OR
P/S870C-96/336
(DMS 2013 Type
5, Class A)
(a) (c)-Alodine 600As Re-
quired
DPM 1453-8 or -10
(a) (b)-PrimerAs Re-
quired
515-700 (Base)
with 910-704 (Cata-
lyst) (DMS 1786
Type 1, Composi-
tion A)
OR
44GN054 Compo-
nent I with
44GN054 Compo-
nent II (DMS 1786
Type 1, Composi-
tion D)
(e)MS21250-08036Bolt2MS21250H08036
or
BACB30LE8HK36
(d)NAS1252-10LTab Washer2SR90550002-7
--Lockwire2 FeetMS20995C41
-NAS679A3Nut2MS21042L3
(a) Or approved equivalent.
(b) Refer to the Qualified Product List (QPL) at the end of the Douglas Material Specification (DMS) for
supplier data.
(c) Refer to the Douglas Process Material Index for supplier data.
(d) Fabricate from Sheet, Alclad 7075-T6 in accordance with Service Rework Drawing SR90550002.
(e) Discard the existing part. Keep the existing part if there are other uses for it.
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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: 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.
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 Chapter 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).
— 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.
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### Page 30

6. Obey all of the warnings and cautions given in the specified manual sections.
7. Refer to APPENDIX A through APPENDIX D for logic diagrams. 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.
8. 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.
9. Some Boeing parts are supplied in a temporary configuration. Those parts are
identified with a 'U' or 'Y' in place of the '-' (dash) in the part number. It is permitted
to install parts identified with a 'U' or 'Y' as an alternative to the '-' (dash) number
part. Boeing Drawing SE10000000, Sheets 5.0 and 6.0 contain more data.
10. If it is necessary to remove more parts for access, you can remove those parts. If
you can get access without removing identified parts, it is not necessary to remove
all of the identified parts. Jacking and shoring limitations must be observed.
11. 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.
12. This service bulletin includes functional test procedures for the systems changed by
this service bulletin. More functional tests can possibly be necessary in accordance
with standard maintenance practices because of interruption to other airplane systems.
13. Use of colors in Figures is based on guidance from the ATA e-Business Program
(ATA) iSpec 2200.
14. 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 number or an
OPTION number, do all of the ACTION numbers for that CONDITION number or
OPTION number.
15. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS
are in Paragraph 1.E., Compliance.
16. 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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### Page 31

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
PART 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY
CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY CURRENT LOW FREQUENCY (ETLF)
INSPECTION
1. RC - Do one of the following options:
a. OPTION 1: OPEN HOLE ETHF INSPECTION
(1) RC Exempt - Open left side elevator hydraulic control valve access door 330LT. Refer
to MD-90 AMM 06-33-00.
(2) Do an open hole ETHF inspection for any crack in the horizontal stabilizer rear spar upper
cap in accordance with FIGURE 1.
(a) CONDITION 1: ANY CRACK FOUND
1) RC Exempt - Do PART 3: ACCESS.
2) Do one of the following options:
a) OPTION 3: HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE
REPAIR
{1} Do a horizontal stabilizer rear spar upper cap splice repair in accordance
with Service Rework Drawing SR90550003-7001.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550003-7005.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
b) OPTION 4: HORIZONTAL STABILIZER REAR SPAR UPPER CAP
REPLACEMENT
{1} Do a horizontal stabilizer rear spar upper cap replacement in
accordance with Service Rework Drawing SR90550002-7001.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550002-7009.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
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### Page 32

3) Repeat PART 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 1: OPEN
HOLE ETHF INSPECTION or OPTION 2: SURFACE ETLF INSPECTION for
any crack at the repeat interval given in Paragraph 1.E., Compliance.
(b) CONDITION 2: NO CRACK FOUND DURING OPTION 1: OPEN HOLE ETHF
INSPECTION
1) RC Exempt - Install and lockwire drilled head bolt in accordance with Service
Rework Drawing SR90550002-7009 or Service Rework Drawing
SR90550003-7005.
2) RC Exempt - Close left side elevator hydraulic control valve access door 330LT.
Refer to MD-90 AMM 06-33-00.
3) Repeat PART 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 1: OPEN
HOLE ETHF INSPECTION for any crack at the repeat interval given in Paragraph
1.E., Compliance.
b. OPTION 2: SURFACE ETLF INSPECTION
(1) Do a surface ETLF inspection for any crack in the horizontal stabilizer rear spar upper
cap in accordance with FIGURE 3.
(a) CONDITION 1: ANY CRACK FOUND
1) RC Exempt - Do PART 3: ACCESS.
2) Do one of the following options:
a) OPTION 3: HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE
REPAIR
{1} Do a horizontal stabilizer rear spar upper cap splice repair in accordance
with Service Rework Drawing SR90550003-7001.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550003-7005.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
b) OPTION 4: HORIZONTAL STABILIZER REAR SPAR UPPER CAP
REPLACEMENT
{1} Do a horizontal stabilizer rear spar upper cap replacement in
accordance with Service Rework Drawing SR90550002-7001.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550002-7009.
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{3} RC Exempt - Do PART 4: CLOSE ACCESS.
3) Repeat PART 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 1: OPEN
HOLE ETHF INSPECTION or OPTION 2: SURFACE ETLF INSPECTION for
any crack at the repeat interval given in Paragraph 1.E., Compliance.
(b) CONDITION 3: NO CRACK FOUND DURING OPTION 2: SURFACE ETLF
INSPECTION
1) Repeat PART 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 2:
SURFACE ETLF INSPECTION for any crack at the repeat interval given in
Paragraph 1.E., Compliance.
2. Put the airplane back to a serviceable condition.
PART 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY
CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY CURRENT LOW FREQUENCY (ETLF)
INSPECTION
1. RC - Do one of the following options:
a. OPTION 5: OPEN HOLE ETHF INSPECTION
(1) RC Exempt - Open right side elevator hydraulic control valve access door 340LT. Refer
to MD-90 AMM 06-33-00.
(2) Do an open hole ETHF inspection for any crack in the horizontal stabilizer rear spar upper
cap in accordance with FIGURE 2.
(a) CONDITION 4: ANY CRACK FOUND
1) RC Exempt - Do PART 3: ACCESS.
2) Do one of the following options:
a) OPTION 7: HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE
REPAIR
{1} Do a horizontal stabilizer rear spar upper cap splice repair in accordance
with Service Rework Drawing SR90550003-7003.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550003-7007.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
b) OPTION 8: HORIZONTAL STABILIZER REAR SPAR UPPER CAP
REPLACEMENT
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### Page 34

{1} Do a horizontal stabilizer rear spar upper cap replacement in
accordance with Service Rework Drawing SR90550002-7003.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550002-7011.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
3) Repeat PART 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 5: OPEN
HOLE ETHF INSPECTION or OPTION 6: SURFACE ETLF INSPECTION for
any crack at the repeat interval given in Paragraph 1.E., Compliance.
(b) CONDITION 5: NO CRACK FOUND DURING OPTION 5: OPEN HOLE ETHF
INSPECTION
1) RC Exempt - Install and lockwire drilled head bolt in accordance with Service
Rework Drawing SR90550002-7011 or Service Rework Drawing
SR90550003-7007.
2) RC Exempt - Close right side elevator hydraulic control valve access door 340LT.
Refer to MD-90 AMM 06-33-00.
3) Repeat PART 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 5: OPEN
HOLE ETHF INSPECTION for any crack at the repeat interval given in Paragraph
1.E., Compliance.
b. OPTION 6: SURFACE ETLF INSPECTION
(1) Do a surface ETLF inspection for any crack in the horizontal stabilizer rear spar upper
cap in accordance with FIGURE 4.
(a) CONDITION 4: ANY CRACK FOUND
1) RC Exempt - Do PART 3: ACCESS.
2) Do one of the following options:
a) OPTION 7: HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE
REPAIR
{1} Do a horizontal stabilizer rear spar upper cap splice repair in accordance
with Service Rework Drawing SR90550003-7003.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550003-7007.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
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### Page 35

b) OPTION 8: HORIZONTAL STABILIZER REAR SPAR UPPER CAP
REPLACEMENT
{1} Do a horizontal stabilizer rear spar upper cap replacement in
accordance with Service Rework Drawing SR90550002-7003.
{2} RC Exempt - Install and lockwire drilled head bolt in accordance with
Service Rework Drawing SR90550002-7011.
{3} RC Exempt - Do PART 4: CLOSE ACCESS.
3) Repeat PART 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 5: OPEN
HOLE ETHF INSPECTION or OPTION 6: SURFACE ETLF INSPECTION for
any crack at the repeat interval given in Paragraph 1.E., Compliance.
(b) CONDITION 6: NO CRACK FOUND DURING OPTION 6: SURFACE ETLF
INSPECTION
1) Repeat PART 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER
CAP OPEN HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE
EDDY CURRENT LOW FREQUENCY (ETLF) INSPECTION, OPTION 6:
SURFACE ETLF INSPECTION for any crack at the repeat interval given in
Paragraph 1.E., Compliance.
2. Put the airplane back to a serviceable condition.
PART 3: ACCESS
1. Remove and keep horizontal stabilizer. Refer to MD-90 AMM 55-10-01 as an accepted procedure.
2. Remove and keep elevator(s). Refer to MD-90 AMM 27-30-02 as an accepted procedure.
3. Remove and keep horizontal stabilizer leading edge(s). Refer to MD-90 AMM 55-12-01 as an
accepted procedure.
PART 4: CLOSE ACCESS
1. Install kept horizontal stabilizer leading edge(s). Refer to MD-90 AMM 55-12-01 as an accepted
procedure.
2. Install kept elevator(s). Refer to MD-90 AMM 27-30-02 as an accepted procedure.
3. Install kept horizontal stabilizer. Refer to MD-90 AMM 55-10-01 as an accepted procedure.
4. If opened, close elevator hydraulic control valve access door 330LT/340LT.
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### Page 36 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
XE=5.931
INBD
LEFT SIDE
LOOKING FORWARD AND DOWN
XE=5.931  (ELEVATOR NOT SHOWN)
LOOKING INBOARD
C-C  FWD
2395865
FIGURE 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY CURRENT
HIGH FREQUENCY (ETHF) INSPECTION
(SHEET 1 OF 2)
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### Page 37

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.
More DataQtyIdentificationNameTaskStep
(a)1-BoltRemove / Keep1
-1MS20002C8WasherRemove / Keep
(b)1-Fastener HoleInspect2
(a) Keep the bolt if it has a drilled head (MS21250H08036 or BACB30LE8HK36). Unless there are other uses
for it, discard the bolt if it does not have a drilled head (MS21250-08036).
(b) Do an open hole ETHF inspection for any crack in accordance with NDTSPM 06-10-01.003. Scan the
circumference of the fastener hole looking for cracks propagating in the radial direction. Evaluate and
verify crack indications found during inspection in accordance with NDTSPM 06-00-07. The signal indica-
tions shown in NDTSPM 06-10-01.003 are for manual scan procedures. Refer to APPENDIX E for illus-
tration of signal indications for automated scan procedures.
FIGURE 1: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY CURRENT
HIGH FREQUENCY (ETHF) INSPECTION
(SHEET 2 OF 2)
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### Page 38 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
XE=-5.931
INBD
LOOKING FORWARD AND DOWN  RIGHT SIDE  XE=-5.931
(ELEVATOR NOT SHOWN)  C
LOOKING INBOARD
FWD  C-C
2396134
FIGURE 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY CURRENT
HIGH FREQUENCY (ETHF) INSPECTION
(SHEET 1 OF 2)
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Work - See page 1 for details.  SO 88

### Page 39

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.
More DataQtyIdentificationNameTaskStep
(a)1-BoltRemove / Keep1
-1MS20002C8WasherRemove / Keep
(b)1-Fastener HoleInspect2
(a) Keep the bolt if it has a drilled head (MS21250H08036 or BACB30LE8HK36). Unless there are other uses
for it, discard the bolt if it does not have a drilled head (MS21250-08036).
(b) Do an open hole ETHF inspection for any crack in accordance with NDTSPM 06-10-01.003. Scan the
circumference of the fastener hole looking for cracks propagating in the radial direction. Evaluate and
verify crack indications found during inspection in accordance with NDTSPM 06-00-07. The signal indica-
tions shown in NDTSPM 06-10-01.003 are for manual scan procedures. Refer to APPENDIX E for illus-
tration of signal indications for automated scan procedures.
FIGURE 2: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN HOLE EDDY CURRENT
HIGH FREQUENCY (ETHF) INSPECTION
(SHEET 2 OF 2)
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### Page 40 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
XE=5.931
SINBD
REAR SPAR  UPPER CAP  LOOKING FORWARD AND DOWN  (ELEVATOR NOT SHOWN)  LEFT SIDE
1.25
-0.75
1.25  XE=5.931
INSPECTION  0.75
AREA
A-A  INBD  2473950
FIGURE 3: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP SURFACE EDDY CURRENT
LOW FREQUENCY (ETLF) INSPECTION
(SHEET 1 OF 2)
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### Page 41

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
(a)--Horizontal Stabilizer
Rear Spar Upper Cap
Inspect1
(a) Do a surface ETLF inspection for any crack in the horizontal stabilizer rear spar upper cap in accordance
with this figure. Refer to MD-90 Airworthiness Limitations Instructions (ALI) Document MDC-94K9000
Non-Destructive Inspection (NDI) procedure 55.11.01.1 as an accepted procedure.
FIGURE 3: LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP SURFACE EDDY CURRENT
LOW FREQUENCY (ETLF) INSPECTION
(SHEET 2 OF 2)
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ALERTALERT

### Page 42 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
XE=-5.931
INBD
RIGHT SIDE
LOOKING FORWARD AND DOWN
(ELEVATOR NOT SHOWN)
REAR SPAR
UPPER CAP
1.25
0.75
• 1.25
XE=-5.931  0.75
INBD  AREA  INSPECTION  2473949
A-A
FIGURE 4: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP SURFACE EDDY CURRENT
LOW FREQUENCY (ETLF) INSPECTION
(SHEET 1 OF 2)
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### Page 43

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
(a)--Horizontal Stabilizer
Rear Spar Upper Cap
Inspect1
(a) Do a surface ETLF inspection for any crack in the horizontal stabilizer rear spar upper cap in accordance
with this figure. Refer to MD-90 Airworthiness Limitations Instructions (ALI) Document MDC-94K9000
Non-Destructive Inspection (NDI) procedure 55.11.01.1 as an accepted procedure.
FIGURE 4: RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP SURFACE EDDY CURRENT
LOW FREQUENCY (ETLF) INSPECTION
(SHEET 2 OF 2)
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### Page 44

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, conditions, and options called out in the logic
diagram.
DescriptionTitle
LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN
HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY
CURRENT LOW FREQUENCY (ETLF) INSPECTION
PART 1
ANY CRACK FOUNDCONDITION 1
NO CRACK FOUND DURING OPTION 1: OPEN HOLE ETHF INSPECTIONCONDITION 2
NO CRACK FOUND DURING OPTION 2: SURFACE ETLF INSPECTIONCONDITION 3
OPEN HOLE ETHF INSPECTIONOPTION 1
SURFACE ETLF INSPECTIONOPTION 2
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIROPTION 3
HORIZONTAL STABILIZER REAR SPAR UPPER CAP REPLACEMENTOPTION 4
2. The table below gives the description for the flag notes called out in the logic diagram.
DescriptionFlag Note Letter
It is acceptable to change the repeat inspection method from Option 1 to
Option 2 or from Option 2 to Option 1 provided the repeat interval for the
previously accomplished inspection method is complied with.
(a)
APPENDIX A:  LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 1: LEFT SIDE HORIZONTAL
STABILIZER REAR SPAR UPPER CAP - OPEN HOLE ETHF OR SURFACE ETLF INSPECTION
(SHEET 1 OF 2)
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ALERTALERT

### Page 45 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
WHICHEVER OCCURS LATER
WITHIN 4,050 FLIGHT
BEFORE 20,000  CYCLES AFTER THE
TOTAL FLIGHT  ORIGINAL ISSUE
CYCLES  DATE OF THIS
SERVICE BULLETIN
DO PART 1, OPTION 1 OR
OPTION 2 FOR ANY CRACK
CONDITION 1  CONDITION 2  CONDITION 3
BEFORE FURTHER  NOT TO EXCEED 3,395  NOT TO EXCEED 833
FLIGHT  FLIGHT CYCLES  FLIGHT CYCLES
OPTION 3:  OPTION 4:  DO PART 1,  DO PART 1,
DO A HORIZONTAL  DO A HORIZONTAL  OPTION 1 FOR  OPTION 2 FOR
STABILIZER REAR  STABILIZER REAR  ANY CRACK  ANY CRACK
SPAR UPPER CAP  SPAR UPPER CAP
SPLICE REPAIR  REPLACEMENT
REFER TO APPENDIX C:
LOGIC DIAGRAM FOR
TABLE 3
2474780
APPENDIX A: LOGIC DIAGRAM FOR PARAGRAPH1.E. COMPLIANCE: TABLE 1: LEFT SIDE HORIZONTAL
STABILIZER REAR SPAR UPPER CAP - OPEN HOLE ETHF OR SURFACE ETLF INSPECTION
(SHEET 2 OF 2)
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### Page 46

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, conditions, and options called out in the logic
diagram.
DescriptionTitle
RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN
HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY
CURRENT LOW FREQUENCY (ETLF) INSPECTION
PART 2
ANY CRACK FOUNDCONDITION 4
NO CRACK FOUND DURING OPTION 5: OPEN HOLE ETHF INSPECTIONCONDITION 5
NO CRACK FOUND DURING OPTION 6: SURFACE ETLF INSPECTIONCONDITION 6
OPEN HOLE ETHF INSPECTIONOPTION 5
SURFACE ETLF INSPECTIONOPTION 6
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIROPTION 7
HORIZONTAL STABILIZER REAR SPAR UPPER CAP REPLACEMENTOPTION 8
2. The table below gives the description for the flag notes called out in the logic diagram.
DescriptionFlag Note Letter
It is acceptable to change the repeat inspection method from Option 5 to
Option 6 or from Option 6 to Option 5 provided the repeat interval for the
previously accomplished inspection method is complied with.
(a)
APPENDIX B: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 2: RIGHT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP - OPEN HOLE ETHF OR SURFACE ETLF INSPECTION
(SHEET 1 OF 2)
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### Page 47 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
WHICHEVER OCCURS LATER
WITHIN 4,050 FLIGHT
BEFORE 20,000  CYCLES AFTER THE
TOTAL FLIGHT  ORIGINAL ISSUE
CYCLES  DATE OF THIS
SERVICE BULLETIN
DO PART 2, OPTION 5 OR
OPTION 6 FOR ANY CRACK
CONDITION 4  CONDITION 5  CONDITION 6
BEFORE FURTHER  NOT TO EXCEED 3,395  NOT TO EXCEED 833
FLIGHT  FLIGHT CYCLES  FLIGHT CYCLES
DO PART 2.  DO PART 2
OPTION 7:  OPTION 8:  OPTION 5 FOR  OPTION 6 FOR
DO A HORIZONTAL  DO A HORIZONTAL  ANY CRACK  ANY CRACK
STABILIZER REAR  STABILIZER REAR
SPAR UPPER CAP  SPAR UPPER CAP
SPLICE REPAIR  REPLACEMENT
REFER TO APPENDIX D:
LOGIC DIAGRAM FOR
TABLE 4
2478906
APPENDIX B: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 2: RIGHT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP - OPEN HOLE ETHF OR SURFACE ETLF INSPECTION
(SHEET 2 OF 2)
Original Issue: June 29, 2016
PROPRIETARY - Copyright © Unpublished  Export Controlled ECCN: 9E991 - BOEING  Work - See page 1 for details.  MD90-55A018  47 of 53

### Page 48

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, conditions, and options called out in the logic
diagram.
DescriptionTitle
LEFT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN
HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY
CURRENT LOW FREQUENCY (ETLF) INSPECTION
PART 1
ANY CRACK FOUNDCONDITION 1
NO CRACK FOUND DURING OPTION 1: OPEN HOLE ETHF INSPECTIONCONDITION 2
NO CRACK FOUND DURING OPTION 2: SURFACE ETLF INSPECTIONCONDITION 3
OPEN HOLE ETHF INSPECTIONOPTION 1
SURFACE ETLF INSPECTIONOPTION 2
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIROPTION 3
HORIZONTAL STABILIZER REAR SPAR UPPER CAP REPLACEMENTOPTION 4
2. The table below gives the description for the flag notes called out in the logic diagram.
DescriptionFlag Note Letter
It is acceptable to change the repeat inspection method from Option 1 to
Option 2 or from Option 2 to Option 1 provided the repeat interval for the
previously accomplished inspection method is complied with.
(a)
APPENDIX C: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 3: POST LEFT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIR OR REPLACEMENT - OPEN HOLE
ETHF OR SURFACE ETLF INSPECTION
(SHEET 1 OF 2)
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: June 29, 2016
MD90-55A018
48 of 53
BOEING SERVICE BULLETIN MD90-55A018
ALERTALERT

### Page 49 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
WITHIN 20,000 FLIGHT CYCLES AFTER
DOING THE LEFT SIDE HORIZONTAL
STABILIZER REAR SPAR UPPER CAP
SPLICE REPAIR OR REPLACEMENT
DO PART 1, OPTION 1 OR
OPTION 2 FOR ANY CRACK
CONDITION 1  CONDITION 2  CONDITION 3
BEFORE FURTHER  NOT TO EXCEED 3,395  NOT TO EXCEED 833
FLIGHT  FLIGHT CYCLES  FLIGHT CYCLES
OPTION 3:  OPTION 4:  DO PART 1.  DO PART 1,
DO A HORIZONTAL  DO A HORIZONTAL  OPTION 1 FOR  OPTION 2 FOR
STABILIZER REAR  STABILIZER REAR  ANY CRACK  ANY CRACK
SPAR UPPER CAP  SPAR UPPER CAP
SPLICE REPAIR  REPLACEMENT
2480334
APPENDIX C: LOGIC DIAGRAM FOR PARAGRAPH 1E. COMPLIANCE: TABLE 3: POST LEFT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIR OR REPLACEMENT - OPEN HOLE
ETHF OR SURFACE ETLF INSPECTION
(SHEET 2 OF 2)
Original Issue: June 29, 2016
PROPRIETARY - Copyright © Unpublished  Export Controlled ECCN: 9E991 - BOEING  MD90-55A018
Work - See page 1 for details.  49 of 53

### Page 50

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, conditions, and options called out in the logic
diagram.
DescriptionTitle
RIGHT SIDE HORIZONTAL STABILIZER REAR SPAR UPPER CAP OPEN
HOLE EDDY CURRENT HIGH FREQUENCY (ETHF) OR SURFACE EDDY
CURRENT LOW FREQUENCY (ETLF) INSPECTION
PART 2
ANY CRACK FOUNDCONDITION 4
NO CRACK FOUND DURING OPTION 5: OPEN HOLE ETHF INSPECTIONCONDITION 5
NO CRACK FOUND DURING OPTION 6: SURFACE ETLF INSPECTIONCONDITION 6
OPEN HOLE ETHF INSPECTIONOPTION 5
SURFACE ETLF INSPECTIONOPTION 6
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIROPTION 7
HORIZONTAL STABILIZER REAR SPAR UPPER CAP REPLACEMENTOPTION 8
2. The table below gives the description for the flag notes called out in the logic diagram.
DescriptionFlag Note Letter
It is acceptable to change the repeat inspection method from Option 5 to
Option 6 or from Option 6 to Option 5 provided the repeat interval for the
previously accomplished inspection method is complied with.
(a)
APPENDIX D: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 4: POST RIGHT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIR OR REPLACEMENT - OPEN HOLE
ETHF OR SURFACE ETLF INSPECTION
(SHEET 1 OF 2)
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: June 29, 2016
MD90-55A018
50 of 53
BOEING SERVICE BULLETIN MD90-55A018
ALERTALERT

### Page 51 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
WITHIN 20,000 FLIGHT CYCLES AFTER
DOING THE RIGHT SIDE HORIZONTAL
STABILIZER REAR SPAR UPPER CAP
SPLICE REPAIR OR REPLACEMENT
DO PART 2, OPTION 5 OF
OPTION 6 FOR ANY CRACK
CONDITION 4  CONDITION 5  CONDITION 6
BEFORE FURTHER  NOT TO EXCEED 3,395  NOT TO EXCEED 833
FLIGHT  FLIGHT CYCLES  FLIGHT CYCLES
OPTION 7:  OPTION 8:  DO PART 2,  DO PART 2
DO A HORIZONTAL  DO A HORIZONTAL  OPTION 5 FOR  OPTION 6 FOR
STABILIZER REAR  STABILIZER REAR  ANY CRACK  ANY CRACK
SPAR UPPER CAP  SPAR UPPER CAP
SPLICE REPAIR  REPLACEMENT
2480336
APPENDIX D: LOGIC DIAGRAM FOR PARAGRAPH 1.E. COMPLIANCE: TABLE 4: POST RIGHT SIDE
HORIZONTAL STABILIZER REAR SPAR UPPER CAP SPLICE REPAIR OR REPLACEMENT - OPEN HOLE
ETHF OR SURFACE ETLF INSPECTION
(SHEET 2 OF 2)
Original Issue: June 29, 2016
Export Controlled ECCN: 9E991 - BOEING  MD90-55A018
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.  51 of 53

### Page 52 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
Impedance Plane
Typical Litt-off Response with Phase Angle Adjusted Correctly
Sweep Display  Impedance Plane
≥ 30°
BASEUNE
Ideal Response from Notch in Standard
Sweep Display  Impedance Plane
‡10%
Clean Hole Acceptable Noise Level
2480330
APPENDIX E: SIGNAL INDICATIONS FOR AUTOMATED SCAN PROCEDURES
(SHEET 1 OF 1)
Original Issue: June 29, 2016
Export Controlled ECCN: 9E991 - BOEING  PROPRIETARY - Copyright © Unpublished  MD90-55A018
Work - See page 1 for details.  52 of 53

### Page 53 (OCR)

BOEING SERVICE BULLETIN MD90-55A018
ALERT  ALERT
Boeing Part Demand Intent
After review of this service bulletin (SB), Boeing asks that the primary engineer fill out this survey to
help Boeing predict the quantity and timing of the Boeing supplied kits.
Airline:
Contact Name:
Date:
Contact E-mail:
— Yes  No Have/will you recommend to your airline to accomplish this SB?
_ Yes  No Would issuance of an Airworthiness Directive change this decision?
When would you likely be starting this SB incorporation? Month/ Year_
How many airplanes per month do you plan to accomplish? Airplane/Month
How many total airplanes do you plan to complete? Total Airplanes
For inspection related SBs, are you planning to replace on condition, or a fleet campaign to replace on
all airplanes regardless of condition?
On Condition  _ Campaign
If you are not incorporating this SB at this time will you please help us understand the reason(s) why?
Your input will help us provide better customer support.
• Cost Prohibitive  Continue Inspections  Other
Operator Comments:
Within 45 days of the SB issue, or as soon after as possible, please scan this form and send to:
KitsandMods@boeing.com
Disclaimer: The data provided in this survey will be used for planning purposes only and does not
constitute a commitment on any part of the airlines to purchase the parts in question, nor does it constitute
a commitment on the part of Boeing to deliver the parts in question. This survey is a projection to help
Boeing forecast demand levels and timing to better support the customers schedule.
2402568
APPENDIX F: PART DEMAND INTENT
(SHEET 1 OF 1)
Original Issue: June 29, 2016
Export Controlled ECCN: 9E991 - BOEING  MD90-55A018
PROPRIETARY - Copyright © Unpublished  Work - See page 1 for details.  53 of 53

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