### Commercial **Airplanes** 

# MD90 Service Bulletin **ALERT Number: MD90-74A002**  Original Issue: August 17, 2010 ATA System: 7400 **SUBJECT:** ENGINE IGNITION - Ignition - Change Fire Handle Shutoff System Wire Routing Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2010 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. 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, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the Boeing livery 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 1 of 21 4.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 2 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**

BLANK PAGE**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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2. Data supplied with this Service Bulletin:. . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3. Installation Drawings Used in the Preparation of this Service Bulletin:. . . . . . . . . . . 13 K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 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:. . . . . . . . . . . . . . . . . . . . . . . . 16 3. Parts Modified and Reidentified: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4. Parts Removed and Not Replaced:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 17 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 3 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 4 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# MD90 Service Bulletin **ALERT Summary**  **Number: MD90-74A002** Original Issue: August 17, 2010 ATA System: 7400 **SUBJECT:** ENGINE IGNITION - Ignition - Change Fire Handle Shutoff System Wire Routing THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. **CONCURRENT REQUIREMENTS** None. **BACKGROUND** The engine fire shutoff handles on the MD-90 airplanes are designed to shutoff fuel at both the wing spar's mechanical fuel fire shutoff valve as well as the electrical solenoid controlled engine fuel shutoff valve in the engine Hydromechanical Unit (HMU). The feature is unique to the MD-90 airplanes and would result in an automatic shutoff of the fuel at the engine HMU when the affected fire handle is pulled. Due to the lack of separation between engine wires, a latent failure in the fire handle fuel shutoff relay circuit has the potential of causing a dual engine shutdown in the event any single engine fuel fire shutoff handle is actuated. Separating the fire handle shutoff system wiring will minimize the possibility of multiple engine shutdown due to single event. If not corrected, inadequate separation has the potential of causing a dual engine shutdown in the event any single engine fuel fire shutoff handle is activated. **ACTION** This service bulletin provides instructions for operators to change the wire routing for the fire handle shutoff system. **EFFECTIVITY** MD-90-30 Airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes. **COMPLIANCE** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. Boeing recommends that the wire routing change for the fire handle shutoff system be done within 4,200 flight-hours after the original issue date on this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 5 of 21**INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are not available for the configuration changes given in this service bulletin. **MANPOWER Elapsed Hours**  **Total Task Hours Airplanes**  7.9 7.9 MD-90-30
**MATERIAL INFORMATION** Boeing supplied Parts/Materials. Refer to Paragraph 2.A., Material - Price and Availability.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 6 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 7 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 8 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# MD90 Service Bulletin **ALERT Number: MD90-74A002**  Original Issue: August 17, 2010 ATA System: 7400 **SUBJECT:** ENGINE IGNITION - Ignition - Change Fire Handle Shutoff System Wire Routing THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER. **1. PLANNING INFORMATION A. Effectivity**  1. Airplanes This service bulletin is for the airplanes shown below:
**DESCRIPTION CONFIGURATION**  **GROUP** Change Fire Handle Shutoff System Wire Routing

- 1

Airplane Models: MD-90-30 **Group Fuselage Num-**  **ber** 1 2094 - 2100 1 2115 1 2117 1 2120 1 2122 - 2123 1 2125 - 2126 1 2129 1 2131 1 2133

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 9 of 21**Group Fuselage Num-**  **ber** 1 2136 1 2138 1 2140 - 2144 1 2146 - 2147 1 2149 - 2150 1 2153 - 2154 1 2156 - 2159 1 2161 - 2166 1 2169 - 2171 1 2173 1 2175 1 2177 1 2179 1 2181 - 2182 1 2184 1 2186 1 2190 - 2191 1 2193 - 2195 1 2197 - 2198 1 2200 1 2202 - 2203 1 2205 1 2207 1 2209 - 2213 1 2215 - 2217 1 2219 - 2233 1 2235 - 2237 1 2240 1 2243 1 2245 1 2248 1 2250 - 2251

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 10 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT Group**  **Fuselage Num- ber**  1 2253 1 2255 - 2263 1 2288 - 2290 1 4001 - 4002 2. Spares Affected None. **B. Concurrent Requirements** None. **C. Reason** The engine fire shutoff handles on the MD-90 airplanes are designed to shutoff fuel at both the wing spar's mechanical fuel fire shutoff valve as well as the electrical solenoid controlled engine fuel shutoff valve in the engine Hydromechanical Unit (HMU). The feature is unique to the MD-90 airplanes and would result in an automatic shutoff of the fuel at the engine HMU when the affected fire handle is pulled. Due to the lack of separation between engine wires, a latent failure in the fire handle fuel shutoff relay circuit has the potential of causing a dual engine shutdown in the event any single engine fuel fire shutoff handle is actuated. Separating the fire handle shutoff system wiring will minimize the possibility of multiple engine shutdown due to single event. If not corrected, inadequate separation has the potential of causing a dual engine shutdown in the event any single engine fuel fire shutoff handle is activated. **D. Description** This service bulletin provides instructions for operators to change the wire routing for the fire handle shutoff system. The work in this service bulletin is done in the maintenance zone(s) given below.
**Affected Maintenance Zones Zone**  **Model** 114, 211 MD-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. Boeing recommends that the wire routing change for the fire handle shutoff system be done within 4,200 flight-hours after the original issue date on this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 11 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT F. Approval**  This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified in this service bulletin comply with the applicable regulations and are FAA approved, as well as European Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on the airplane in its original Boeing delivery configuration or as modified by other approved Boeing changes. If an airplane has a non-Boeing modification or repair that affects a component or system also affected by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval before incorporating this service bulletin. **G. Manpower** The table below shows an estimate of the task hours necessary to do this inspection/modification 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 Hours Task Hours**  **Number of Persons Task**  0.2 0.2 1 Open Circuit Breaker 0.5 0.5 1 Open Access 6.5 6.5 1 Change and Coil/Stow Wires 0.2 0.2 1 Close Circuit Breaker 0.5 0.5 1 Close Access 7.9 7.9 TOTAL FOR EACH AIRPLANE
**H. Weight and Balance Changes**
**Moment Change (MEW) IN.-LBS**  **Mfr's Empty Weight (MEW)**  **LBS Approximate Sta**  **tion (Inches) Airplane**  + 84.0 + 0.6 + 140.0 MD-90-30
**I. Electrical Load Data** Not changed.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 12 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT J. References**  1. Existing Data: a. Standard Wiring Practices Manual (SWPM) 20-00-03, 20-00-09, 20-00-13, 20-00-16, 20-10-01, 20-10-04, 20-20-01, 20-20-02, 20-31-00. b. MD90 Aircraft Maintenance Manual (AMM) 06-31-00, 06-32-00, 24-00-00. 2. Data supplied with this Service Bulletin: No data is supplied with this service bulletin. To obtain the data necessary to support this service bulletin submit a data request to: Data and Services Management MS D800-0019 3855 Lakewood Boulevard Long Beach, California 90846 Phone: (562) 593-6996 Fax: (562) 593-2001 E-mail: dse.boecom@boeing.com a. Drawings:
**ADCN DCN/REV**  **Sheet Title**  **Drawing No**

- C DWG FIRE HANDLE SHUTOFF SYS WIRE SEPARATION SR90740002
3. Installation Drawings Used in the Preparation of this Service Bulletin: **Change Title**  **Document Number** BR WIRE INSTALLATION - UPPER NOSE 5964560
DD WIRE INSTALLATION - LOWER NOSE 5964562
BJ WIRE INSTALLATION - ELECTRI- CAL POWER CENTER, OVHD SW PNLS & HOUSING 5964566

These drawings were used to prepare this service bulletin. These drawings are not necessary to make the specified changes, and are not supplied with this service bulletin. These drawings may not be applicable to all airplane configurations or operators. **K. Publications Affected** 1. Publications:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 13 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT Chapter-Section**  **Publication** 26-11-013, 74-11-011, 74-11-012 Wiring Diagram Manual 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary. **L. Interchangeability and Intermixability of Parts** Refer to Paragraph 2.C., Parts Necessary for Each Airplane, for interchangeability and intermixability information.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 14 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT 2. MATERIAL INFORMATION**  **A. Material - Price and Availability** Boeing can supply the parts 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 parts 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)**  **Name Kit Number** 

$489.00 90 Service Kit SA90740002-3 **B. Industry Support Information** Boeing warranty remedies are not available for the configuration changes given in this service bulletin. **C. Parts Necessary For Each Airplane** 1. Kits/Parts:
**Kit SA90740002 Notes**  **Existing Part Number Name**  **QTY New Part Number**  **-101 -3** 

- - SA90740002-3 WIRE PACKAGE

- 1 SA90740002-101 DMS 2109 SLEEVE

- .125 I.D. X 310 IN. SR90740002-3 (a) END CAP, T/C 914 - 10 CYW20

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 15 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT Kit SA90740002**  **Notes Existing Part Number**  **Name QTY**  **New Part Number -101**  **-3** Remove and install socket or pin. Refer to SWPM 20-00-16. SOCKET, T/C 1123 - 1 DC39-16S
SOCKET, T/C 1124 - 1 DC39-20S (b) WIRE CODE 801 310 IN.

- D2426-1C-20NM SLEEVE 2
- SA90740002-5 (1/8 DIA X 2.0 INCHES) (DMS 2399, Type 3 or Equivalent) TAG 2
- DPM 6101 (a) SR90740002-5 (DMS 2379) sleeving is an approved alternate for SR90740002-3 (DMS 2109) sleeving. (b) Refer to SWPM 20-00-13 Table 206 for approved alternate wires. 2. Parts and Materials Supplied by the Operator:
**Notes Name**  **QTY Part Number/ Specifi-**  **cation** (a) STRAP, TIEDOWN As Required 9D0254-1-1-9 or (b) (PLT2S-9 or SST2S-9) or Equivalent (c) TAPE, LACING & TYING As Required 18 DZ BLK (DPM 731-6) or Equivalent TAPE, TYPING, GLASS FIBER As Required 18XTZ or 23XTZ (DMS 2089) or Equivalent
CAGE The Boeing Company (a) Can be purchased from: 81205 7755 East Marginal Way South Seattle, Washington 98108 06383 Panduit Corporation (b) Can be purchased from: 17301 Ridgeland Avenue Tinley Park, Illinois 60477 7F993 Gudebrod, Incorporated (c) Can be purchased from: 262 King Street Pottstown, Pennsylvania 19464

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 16 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 17 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 18 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**

BLANK PAGE**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. The instructions identified in Paragraph 3.B., Work Instructions, and the Figure(s) give the recommended sequence of steps. The sequence of steps to do this service bulletin can be changed. 2. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 3. Equivalent parts are listed in the AEPL, Drawing 7595071. 4. Refer to these SWPM chapters for applicable operations, as accepted procedures: – SWPM 20-00-03 - Identification of Electrical wires. – SWPM 20-00-09 - Electrical Identification and Shop Practice. – SWPM 20-00-13 - Alternate wire type list. – SWPM 20-00-16 - Electrical Wire End Termination Codes. – SWPM 20-10-01 - Wire Installation Procedures. – SWPM 20-10-04 - Coil and Stow Excess wire Length. – SWPM 20-20-01 - Copper Electrical Terminals - Commercial. – SWPM 20-20-02 - Terminal Junction Blocks - Commercial. – SWPM 20-31-00 - Electrical Connectors - General Requirement - Commercial. 5. Review and understand all general notes of Service Rework Drawing SR90740002, sheets 3.0 and 3.1. 6. Obey all of the warnings and cautions given in the specified manual sections. 7. These work instructions refer to procedures included in other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 19 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT B. WORK INSTRUCTIONS**  1. Remove electrical power from airplane. Refer to MD90 AMM 24-00-00 as an accepted procedure. 2. Gain access to area of modification by opening the access doors as follows:
**MORE DATA LOCATION**  **ACCESS DOOR** MD90 AMM 06-31-00 Electrical/Electronic (E/E) Com- partment 110BL
MD90 AMM 06-32-00 Upper Nose Pedestal Floor, STA 120.000 Wire Trough Cover
MD90 AMM 06-32-00 Forward Cabin EPC Electrical Power Center (EPC) Shroud 3. Open circuit breakers and install safety tags as follows:
**Name Number**  **Row/Col Location**  Left Engine Start Switch B1-1097 U/34 Lower EPC Right Engine Start Switch B1-1096 X/39 Lower EPC Left Fuel Shutoff Solenoid B1-1079 Z/32 Lower EPC Fire Warning Lights B1-192 W/42 Lower EPC Right Fuel Shutoff Solenoid B1-1080 B/10 Overhead Panel 4. Disconnect, coil and stow existing wire in accordance with Service Rework Drawing SR90740002, sheet 7.0. 5. Install new wire in accordance with Service Rework Drawing SR90740002, sheet 7.0. 6. Disconnect, coil and stow wires in accordance with Service Rework Drawing SR90740002, sheets 4.0, 4.1, 6.7, 6.8, and General Notes 16 and 20. 7. Do a continuity check on new wire. 8. Remove safety tags and close circuit breakers as follows:
**Name Number**  **Row/Col Location**  Left Engine Start Switch B1-1097 U/34 Lower EPC Right Engine Start Switch B1-1096 X/39 Lower EPC Left Fuel Shutoff Solenoid B1-1079 Z/32 Lower EPC Fire Warning Lights B1-192 W/42 Lower EPC Right Fuel Shutoff Solenoid B1-1080 B/10 Overhead Panel
9. Close the access doors as follows:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 20 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT MORE DATA**  **LOCATION ACCESS DOOR**  MD90 AMM 06-31-00 Electrical/Electronic (E/E) Com- partment 110BL
MD90 AMM 06-32-00 Upper Nose Pedestal Floor, STA 120.000 Wire Trough Cover
MD90 AMM 06-32-00 Forward Cabin EPC Electrical Power Center (EPC) Shroud 10. Restore electrical power to airplane. Refer to MD90 AMM 24-00-00 as an accepted procedure. 11. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: August 17, 2010 MD90-74A002 21 of 21 **BOEING SERVICE BULLETIN MD90-74A002 ALERT**  **ALERT**