Part of GE’s Aviat ion Business

 SERVICE BULLETIN .

SERVICE BULLETIN

SERVICE BULLETIN D8400-61-A66

TRANSMITTAL LETTER FOR REVISION NO. 8

Oct 31/13

1. REASON

A. The Compliance paragraph 1. D. (1) (b) has been revised. The sealant must be re-applied at the major 

inspection/restoration interval for the equipment as defined in Dowty Propellers Publication 1096 Part 1 

and in accordance with this service bulletin.

B. Alternative sealant added.

2. ACTION

A. Remove and destroy existing pages 1 to 6 of the service bulletin and replace with revised pages 1 to 6 

dated Oct 31/13.

Dowty Propellers

Anson Business Park, Cheltenham Road East, Gloucester, GL2 9QN ENGLAND

Telephone: 01452 716000 Facsimile: 01452 716001

Page 1 of 6

CAGE CODE: U7387

For Europe, Africa, India and

Middle East contact:

Dowty Propellers

Anson Business Park

Cheltenham Road East,

Gloucester, GL2 9QN, United Kingdom

T: + 44 (0)1452 716000

F: + 44 (0)1452 716001

For Asia, Australasia and the Pacific

contact:

Dowty Propellers

Anson Business Park

Cheltenham Road East,

Gloucester, GL2 9QN, United Kingdom

T: + 44 (0)1452 716000

F: + 44 (0)1452 716001

For the Americas

contact:

Dowty Propellers

114 Powers Court

Sterling, VA 20166

United States of America

T: + 1 (703) 421 4434

F: + 1 (703) 450 0087

Copyright (2009), GE Aviation Systems Ltd., U.K

The information contained in this document is GE Aviation Systems Ltd proprietary information and is disclosed in confidence. It is the 

property of GE Aviation Systems Ltd and shall not be used, disclosed to others or reproduced without the express written consent of GE 

Aviation Systems Ltd, including, but without limitation, it is not to be used in the creation, manufacture, development, or derivation of any 

repairs, modifications, spare parts, designs, or configuration changes or to obtain FAA, CAA, EASA, or any other government or 

regulatory approval to do so. If consent is given for reproduction in whole or in part, this notice and the notice set forth on each page of 

this document shall appear in any such reproduction in whole or in part.

All technical documentation and information contained herein, with respect to assembly and disassembly, cleaning, inspection methods 

and limits, repair methods and limits, operational limits, life limits and the like, have been developed and approved for use with this 

equipment and parts that have been manufactured and/or approved by GE and that have been maintained in accordance with GE 

technical documentation and recommendations. GE has no contractual or legal obligation for, nor knowlege of, non-GE-approved parts 

and repairs. Accordingly, this document is not intended to apply to non-GE-approved parts and repairs.

ALERT

Manual Ref: 61-10-49

SERVICE BULLETIN

PROPELLER - HUB, ACTUATOR AND BACKPLATE ASSEMBLY - APPLICATION OF SEALANT BETWEEN 

BUSBARS AND BACKPLATE

1. Planning Information

WARNING: FAILURE TO IMPLEMENT ANY INSTRUCTION GIVEN HERE, AS AMENDED FROM TIME TO 

TIME BY DOWTY PROPELLERS, MAY ENDANGER HEALTH AND SAFETY.

A. Effectivity

Aircraft affected : de Havilland Dash 8 Series 400, 401 and 402

Propeller Type No.: R408/6-123-F/17

Unit affected : Hub, Actuator and Backplate Assembly LRU

Part No. : 697037001

Serial Nos. : All Hub, Actuator and Backplate Assembly LRU’s from Serial No. DAP0347 will 

include this service bulletin before delivery

B. Reason

(1) There have been reports of short circuits between the busbar assemblies and the backplate 

assembly. This has caused double generator failure on aircraft in flight.

VP4084

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ALERT

C. Description

(1) 3M 5300, 3M 550 FC or 3M 4200 sealant is to be applied between the busbar assemblies and the 

backplate assembly. The sealant has been successfully used as a solution to the problem.

(2) The sealant layer will add extra insulation and provide a bond between the two components.

D. Compliance

(1) ALERT

(a) This service bulletin must be completed on all units within 5,000 FH from the release of this 

service bulletin. 

(b) The sealant must be re-applied at the major inspection/restoration interval for the equipment 

as defined in Dowty Propellers Publication 1096 Part 1 and in accordance with this service 

bulletin. This is applicable to all unit serial numbers.

(c) The requirement for the continued inspection of Hub, Actuator and Backplate Assemblies, 

Part No. 697037001, can be cancelled by the incorporation of a modified backplate and 

slipring assembly in accordance with Dowty Propellers Service Bulletin D8400-61-94.

E. Approval

(1) This service bulletin was approved and classified as ALERT. The technical content of this service 

bulletin was approved under the authority of Design Organisation Approval No. EASA.21J.008. 

This service bulletin is the subject of EASA airworthiness directive 2009-0114.

F. Manpower

(1) This service bulletin will take approximately 2 hours to complete for each hub actuator and 

backplate LRU.

NOTE : The above manhours are given for maintenance schedule functions only. The estimate 

includes the time to do the maintenance procedures in the Accomplishment Instructions 

only. It does not include the time to prepare the equipment for the maintenance 

procedures.

G. Weight and Balance

(1) None.

H. References

(1) Dowty Propellers Component Maintenance Manual 61-10-49.

(2) Dowty Propellers, Propeller MAintenance Manual, Publication 1096 Part 1.

I. Other Publications Affected

(1) Dowty Propellers Component Maintenance Manual 61-10-49.

2. Material information

A. Material

To complete this modification make an order for Modification Set VP4084. This modification set will have 

the items that follow:

Qty for

Part No. Each Unit Name Price/Supply

(1) P999358 0.5 tube 3M Sealant 5300, Black ) Apply to Dowty Propellers

or Alternative 3M Sealant 550 FC, Black ) for the supply date of the

or ) Modification item

TBA 0.5 tube 3M Sealant 4200, Black )

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ALERT

B. The modification will be included in new production by the manufacturer from Serial No. DAP0347. 

Pre modification spares will not be kept. Quantities are for each unit.

New Qty for Pre S.B. Instructions

Part No. Each Unit Name Part No.

(1) 697037001 1 Hub, Actuator and 697037001

Backplate Unit

(2) 697037203 1 Slip Ring and 697037202 ) Amend part no.

Backplate Assembly ) as necessary.

) Refer to para 3.C.

C. Tooling

(1) None.

3. Accomplishment Instructions

The figure/item numbers in parentheses in the text agree with those used in the illustrated parts list. Only the 

primary figure/item numbers are used.

A. Procedure 

(1) Off-wing - Disassembled (Refer to Figure 1)

(a) Remove the slipring and backplate assembly (2-50) from the hub and actuator: refer to the 

Component Maintenance Manual.

(b) Remove the self locking nuts (2-80) and the washers (2-90) which attach the busbar 

assemblies (2-140 and 2-170) to the backplate assembly (4-20).

(c) Remove the bolts (2-100) and the washers (2-110) which attach the slipring assembly 

(2-200) to the backplate assembly (4-20).

(d) Remove the slipring assembly (2-200) with the attached busbar assemblies (2-140 and 

2-170) from the backplate assembly (4-20).

(e) Fully clean the busbar assemblies (2-140 and 2-170) and the backplate assembly (4-20): 

refer to the Component Maintenance Manual, CLEANING.

(f) Refer to Figure 1. Apply a thin layer of black 3M 5300, 3M 550 FC or 3M 4200 sealant to the 

rear of the busbar assemblies (2-140) or (2-170) (the face which is adjacent to the backplate 

assembly when assembled) at the position shown and length given.

(g) Assemble the slipring assembly (2-200) with the attached busbar assemblies (2-140 and 

2-170) to the backplate assembly (4-20): refer to the Component Maintenance Manual.

(h) Make sure that the busbar assemblies (2-140) or (2-170) are flush against the backplate 

assembly (4-20) with the minimum thickness of sealant. The quantity of sealant must be 

enough to make a good bond between each busbar and the backplate.

(i) Clean any unwanted sealant from the backplate assembly (4-20) and busbar assemblies 

(2-140 and 2-170).

(j) Allow the sealant to cure for 45 minutes.

(k) Complete the assembly of the slipring assembly (2-200) to the backplate assembly (4-20): 

refer to the Component Maintenance Manual.

(l) Complete the assembly of the propeller: refer to the Component Maintenance Manual.

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ALERT

B. Procedure

(1) On-wing - Assembled (Refer to Figure 2)

(a) Loosen the self locking nuts which attach the busbar assemblies to the backplate assembly 

(4-20)

(b) Use a blunt tool to carefully lift the busbar assembly from the backplate. Make sure that you 

do not permanently distort the busbar assembly.

(c) Fully clean the busbar assembly and the backplate assembly: refer to the Component 

Maintenance Manual, CLEANING.

(d) Refer to Figure 1. Apply a thin layer of black 3M 5300, 3M 550 FC or 3M 4200 sealant to the 

rear of the busbar assembly (the face which is adjacent to the backplate assembly when 

assembled) at the position shown and length given. Refer to PS5709-21.

(e) Remove any excess sealant with a suitable tool such as a soft spatula.

(f) Remove the blunt tool used to lift the busbar assembly from the backplate assembly.

(g) Press the busbar assembly against the surface of the backplate to make sure that the sealant 

makes a good bond.

(h) Make sure that the busbar assembly is flush against the backplate assembly with the 

minimum thickness of sealant. The quantity of sealant must be enough to make a good bond 

between each busbar and the backplate.

(i) Torque the self locking nuts which attach the busbar assemblies to the backplate assembly to 

28.5 to 31.5 lbf in (3,22 to 3,56 N m): refer to PS 51002-1.

(j) Clean any unwanted sealant from the backplate assembly and busbar assemblies.

(k) Repeat the procedure for each busbar.

(l) Do a check of each busbar assembly to make sure that they are not distorted.

CAUTION : MAKE SURE THAT THE CLEARANCE BETWEEN THE BUSBAR ASSEMBLIES AND 

THE DUAL PULSE PROBE ASSEMBLY IS SATISFACTORY. REFER TO AMM TASK 

61-20-06-820-801.

(m) Allow the sealant to cure for a minimum of 45 minutes before returning the propeller to 

service.

C. Make a Record

(1) When the instructions of this service bulletin have been completed:

- Change the part number of the slip ring and backplate assembly to 697037203

- Write Service Bulletin D8400-61-A66 in the propeller log book.

Feb 9/07 D8400-61-A66

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ALERT

Application of 3M 5300, 3M 550 FC or 3M 4200 Sealant - Propeller Off-wing - Disassembled

Figure 1

D8400-00283-1

A

BACKPLATE 

ASSEMBLY (4-20)

225 mm

(8.86 in)

37 mm (1.46 in)

BUSBAR

ASSEMBLIES (2-140)

DETAIL A

BACKPLATE ASSEMBLY

(4-20)

APPLY 3M 5300, 3M 550 FC OR 

3M 4200 SEALANT TO THE REAR

OF THE BUSBAR ASSEMBLIES

(2-140) AND (2-170) BETWEEN THE

BUSBAR ASSEMBLIES AND THE

BACKPLATE ASSEMBLY (4-20) 

Feb 9/07 D8400-61-A66

Oct 31/13 (Revision 8)
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ALERT

Application of 3M 5300, 3M 550 FC or 3M 4200 Sealant - Propeller On-wing - Assembled

Figure 2

D8400-00284-1

SECTION A - A

BUSBAR

ASSEMBLIES 

BACKPLATE ASSEMBLY

A

A

225 mm 

(8.86 in)

37 mm 

(1.46 in)

A

A

APPLY 3M 5300, 3M 550 FC OR 

3M 4200 SEALANT TO THE REAR

OF THE BUSBAR ASSEMBLIES

BETWEEN THE BUSBAR ASSEMBLIES

AND THE BACKPLATE ASSEMBLY

Feb 09/07 D8400-61-A66

Oct 31/13 (Revision 8)