# D

S.B. 84 ---28 ---07 Page 1 of 12 01 Aug 2008 L.S 

# SERVICE BULLETIN Customer Support
ATA SYSTEM: 2800 NUMBER: 84 ---28 ---07



### BOMBARDIER AEROSPACE REGIONAL AIRCRAFT CONSIDER THIS SERVICE BULLETIN TO BE PARTICULARLY SIGNIFICANT AND URGES OPERATORS TO PROMPTLY EVALUATE THE CONTENTS

SUBJECT: Fuel --- Fuel Indication --- High Level Sensor --- Application of Sealant to exposed end of Sensor Terminal Block Screws --- Special Inspection and Rectification --- ModSum 4 ---113580

1. PLANNING INFORMA TION
A. Effectivity Aircraft Affected: In ---Service: DHC ---8 Aircraft Models 401 and 402 Serial Numbers 4119 thru 4205. Production: ModSum 4 ---113580 is not applicable to aircraft in production.
NOTE: The instructions in this Service Bulletin are only applicable to the systems and parts installed at the time of delivery on the aircraft or as changed by Bombardier Aerospace Service Bulletin(s). Before you do this bulletin, examine all STC or equivalent action changes to make sure this bulletin can be completed. Spares Affected: None

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 2 of 12 01 Aug 2008 L.S B. Reason Problem: This service bulletin (ModSum 4 ---113580) is issued as a result of FAA certification requirements conveyed by Special Federal Aviation Regulation 88 (SFAR 88). The regulations are set to enhance fuel tank system safety. During inspection of a production aircraft, it was discovered that a layer of sealant was not applied to completely cover (dome seal) the exposed threaded end of each of the 3 terminal block screws (part of the high level sensor) per production requirements. Solution: This service bulletin conveysa special inspection and rectification procedure required to make sure affected aircraft are compliant with production build and SFAR 88 requirements. The special inspection part of this service bulletin is accomplished to determine if the exposed threaded end of each terminal block screw is/was dome sealed during production build. The rectification part of this service bulletin conveys ModSum 4 ---113580. The ModSum permits application of sealant to completely cover (dome seal) the exposed threaded end of each terminal block screw that was missed during the production build. ModSum 4 ---113580 is designed to enhance fuel tank system safety and meet FAA SFAR 88 certification requirements. C. Description The procedures in this service bulletin give the instructions to do the tasks that follow: --- lock pins are installed thru each main gear and main gear door mechanism --- the nose gear ground lock is engaged --- the fuel tanks are pressure defueled --- all aircraft electrical power is selected to OFF --- work platforms or ladders are set up around the wings --- certain left and/or right outer wing panels are removed --- fuel tanks are vented --- the exposed end of each high level sensor terminal block screw is dome sealed --- certain left and/or right outer wing panels are installed --- the fuel tanks are refueled --- log book entries are made

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 3 of 12 01 Aug 2008 L.S D. Compliance Bombardier Inc. recommends incorporation of ModSum 4 ---113580 at the earliest opportunity unless otherwise directed by the operator’s airworthiness authority. E. Approval The technical content of this Service Bulletin has been approved under the authority of the Transport Canada Civil Aviation (TCCA) Design Approval Organization No: DAO #93 ---Q ---02. F. Manpower It will take an estimated 6 man ---hours to complete this Service Bulletin. The breakdown of the man ---hours is shown in the table that follows:
TASK MAN ---HOURS Job Set ---Up 2.50* Procedure 1.00 Test / RTS NA Close ---Out 2.50**

* time required to defuel and vent fuel tank not included ** cure time for sealant not included. G. Material --- Price and Availability This service bulletin is self ---contained (illustrated). A drawing kit is not required to accomplish this service bulletin. H. Tooling --- Price and Availability None I. Weight and Balance None J. Electrical Load Data Not affected

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 4 of 12 01 Aug 2008 L.S K. Publications Affected ModSums Manual PSM 1 ---84 ---12

.................................. L. References The initial issue of this service bulletin was prepared to the engineering drawings and related data that follows: DRAWING SHEET REV

8DK4147 1

--- ModSum 4 ---113580 Rev. ---A ModSum 4Q113580 Rev. ---A PCA 42424 (for internal reference only)

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 5 of 12 01 Aug 2008 L.S 2. MATERIAL INFORMA TION A. Parts Required Per Aircraft (1) No parts are required to accomplish the intent of this service bulletin. (2) If it is required to dome seal the exposed threaded end of any terminal screw, the following material(s) are required for the completion of this service bulletin. The materials may be procured as single items from Bombardier Aerospace Regional Aircraft or purchased directly from industry sources. Addresses of manufacturers and suppliers not shown below are listed in the Consumable Products Manual PSM 1 ---84 ---18

Part Number Qty. Per Aircraft Description Remarks DHMS S3.01 1/4 Pint Type I or Type II Class B SealingCompound, Temperature Resistant
DS108F 1/4 Pint Solvent, De --- greaser Dynamold
As required Cotton, Lint free Cloth
Sealant DHMS S3.01 available from: PRC ---Desoto Canada Inc. 5676 Timberlea Blvd., Mississauga, Ontario L4W 4M6 Canada

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 6 of 12 01 Aug 2008 L.S B. Parts Required to Modify Spares None C. Special Tools and Equipment Required None D. Existing Parts Accountability None
3. ACCOMPLISHMENT INSTRUCTIONS A. Job Set ---Up (1) Make sure that lock pins are installed thru each main gear and main gear door mechanism. (2) Make sure the nose gear ground lock is engaged. (3) Pressure defuel the applicable fuel tank (refer to TASK 12 ---10 ---28 ---650 ---802). (4) Placard and select all aircraft electrical power to OFF. Obey all relevant WARNINGS and CAUTIONS detailed in Maintenance Manual PSM 1 ---84 ---2 Chapter 24. (5) Set up work platforms or ladders around and/or under the left (and/or right) wing to permit access to the fuel tanks. Make sure that the work platforms or ladders are electrically grounded. (6) Make sure to obey the fuel system safety precautions (refer to AMM TASK 28 ---00 ---00 ---910 ---801. (7) Obey the electrical/electronic safety precautions (refer to AMM TASK 24 ---00 ---00 ---910 ---801). (8) Obey the electrostatic discharge safety precautions (refer to AMM TASK 24 ---00 ---00 ---910 ---802).

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 7 of 12 01 Aug 2008 L.S (9) Remove the left and/or right wing panels that follow: ACCESS DESIGNATION 524FT (and/or 624FT right wing) Outer Wing Fuel Access Panels (a) For removal the outer wing fuel access panels refer to AMM TASK 57 ---21 ---01 ---000 ---801. (10) Prepare fuel tank for access. Make sure no fuel or fuel vapors are present before working on aircraft (refer to AMM TASK 28 ---10 ---00 ---840 ---801). B. Procedure Part A --- Special Inspection (1) Locate the high level sensor in the left and right side wing (between rib stations Yw ---389.019 and Yw ---407.019) refer to Figure 1. (a) Using a suitable light look at the inner side of the terminal block and determine if the threaded end of all 3 of the terminal block screws are or are not completely covered with sealant (dome sealed) refer to Figure 2. 1 If the threaded end of all 3 terminal block screws arecompletely covered with sealant (dome sealed ) refer to the close out section of this service bulletin and return the aircraft to service. 2 If the threaded end of any terminal block screw is notcompletely covered (dome sealed) refer to Part B --- Rectificationthat follows. Part B --- Rectification --- ModSum 4 ---113580 (1) Dome seal the exposed threaded end ofeach terminal block screw on the inner side of the high level sensor terminal block as follows (refer to Figure 2): (a) Clean and degrease exposed threaded end of each terminal block screw on the inner side of the high level sensor terminal block with solvent DS 108F (or equivalent). (b) Dome seal the exposed threaded end of each terminal block screw with sealant DHMS S3.01 Class B, Type I or Type II. Make sure the threaded end of each terminal block screw is completely covered to reduce possibility of wire contact (refer to AMM TASK 51 ---23 ---00 ---390 ---801). NOTE: Proper application of sealant precludes the possibility of other wires in the immediate area from making contact with the threaded end of each terminal block screw.

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 8 of 12 01 Aug 2008 L.S C. Close Out (1) Install the left and/or right wing panels that follow: ACCESS DESIGNATION 524AT (and/or 624AT right wing) Outer Wing Fuel Access Panels (a) For installation the outer wing fuel access panels refer to PSM 1 ---84 ---2 TASK 57 ---21 ---01 ---400 ---801. (2) Remove all tools equipment from the work area. (3) On incorporation of this ModSum make an entry that conforms to local regulatory requirements in the applicable logbook(s). Enter this ModSum number only after complete incorporation of all work defined in this service bulletin.

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 9 of 12 01 Aug 2008 L.S High Level Sensor --- Locator View Figure 1 Sheet 1 SEE FIGURE 1 SHEET 2 LEFT SIDE SHOWN RIGHT SIDE SIMILAR

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 10 of 12 01 Aug 2008 L.S High Level Sensor --- Locator View Figure 1 Sheet 2 Yw --317.019 Yw --335.019 Yw --353.019 Yw --371.019 Yw --389.019 Yw --407.019 FUEL QUANTITY PROBE 2800--TU9

VIEW LOOKING AFT VIEW LOOKING DOWN HIGH LEVEL SENSOR A

SEE DETAIL ‘A’ ON FIGURE 2

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 11 of 12 01 Aug 2008 L.S High Level Sensor Terminal Block --- Application of Sealant Figure 2 Sheet 1 1

NOTE 1 Dome seal the exposed threaded end of each terminal screw on the inside of terminal block. Refer to Fig 2 Sheet 2 for additional view. DETAIL A VIEW LOOKING ON HIGH LEVEL SENSOR VIEW LOOKING ON FORWARD FACE OF TERMINAL BLOCK

VIEW LOOKING ON INSIDE

OF TERMINAL BLOCK TERMINAL BLOCK 1

### SERVICE BULLETIN 84 ---28 ---07

S.B. 84 ---28 ---07 Page 12 of 12 01 Aug 2008 L.S High Level Sensor Terminal Block --- Application of Sealant Figure 2 Sheet 2 END OF TERMINAL BLOCK SCREWS TO BE COVERED WITH SEALANT ‘‘DOME SEALED’’ NOTE: 2 of 3 SCREWS SHOWN. 3’RD SCREW NOT IN VIEW

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