# Bombardier Service Bulletin 84-27-52

## Copies (2)

Copies the FAA filed in AD dockets on regulations.gov, newest revision first. A newer revision may exist.

- Revision A ("U.S. DOT/FAA - Service Bulletin 84-27-52A"), 14 pages: PDF https://openairdocs.org/files/sha256/74/22/7422fe29c42a0168c1a279984b0c60ce344ecf491aac463b02006cdd1091b0a4; text https://openairdocs.org/service-documents/bombardier/sb-84-27-52/file/7422fe29c42a.md. Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2012-1222; AD 2013-13-17 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- U.S. DOT/FAA - Service Information ("U.S. DOT/FAA - Service Information"), 12 pages: PDF https://openairdocs.org/files/sha256/a6/63/a663c44da9c9867976e3b92d07a348953e652c7379802520a7a393025bc14ced; text https://openairdocs.org/service-documents/bombardier/sb-84-27-52/file/a663c44da9c9.md. Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2011-0260; AD 2011-13-08 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.

## Details

- Manufacturer: [Bombardier](https://openairdocs.org/service-documents/bombardier.md)
- Type: Service bulletin (Service Bulletin)
- Number: 84-27-52
- Latest revision known: 84-27-52, Revision A, dated March 5, 2012 (OpenAirDocs)
- Page: https://openairdocs.org/service-documents/bombardier/sb-84-27-52

## ADs that cite it (2) (OpenAirDocs)

Newest first, with the revision each names, as OpenAirDocs read it from the AD's text.

- [AD 2013-13-17](https://openairdocs.org/ad/2013-13-17.md), effective Aug 26, 2013: Revision A
- [AD 2011-13-08](https://openairdocs.org/ad/2011-13-08.md), effective Aug 1, 2011: No revision named

Also cited in [1 proposed AD](https://openairdocs.org/service-documents/bombardier/sb-84-27-52/proposed.md).

## Text (14 pages)

Revision A, the newest copy. Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2012-1222; AD 2013-13-17 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. Each page's text from the PDF; open the PDF at a page with #page=N.

### Page 1

Revision ‘A’ 05 Mar 2012
DHC-8 (DASH 8)
SERVICE BULLETIN 84-27-52
Flight Controls - Elevator Control System - PCU Swaged Bearings Worn
- Special Inspection & Rectification
This page transmits Revision ‘A’ of Service Bulletin 84-27-52, pages 1 thru
10, dated: 05 Mar 2012
This service bulletin is re-issued in its entirety for the reasons that follow:
-t h e Effectivity section is revised
- updated SB revision level in References
The Compliance in the previous issue of this service bulletin is not affected
by this revision. No additional rework to the aircraft is introduced by this
revision.
Remove initial issue of Service Bulletin 84-27-52 and replace with attached.
Previous issues of Service Bulletin 84-27-52:
Initial issue - Pages 1 thru 10 dated 25 May 2010

### Page 2

(No text on this page.)

### Page 3

D
S.B. 84-27-52
Page 1 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
Customer
Support
ATA SYSTEM: 2730 NUMBER: 84-27-52
BOMBARDIER AEROSPACE REGIONAL AIRCRAFT CONSIDER THIS
SERVICE BULLETIN TO BE PARTICULARLY SIGNIFICANT AND
URGES OPERATORS TO PROMPTLY EVALUATE THE CONTENTS
SUBJECT: Flight Controls - Elevator Control System - PCU Swaged Bearings
Worn - Special Inspection & Rectification
1. PLANNING INFORMATION
A. Effectivity
Aircraft Affected:
In-Service: All DHC-8 Aircraft Models 401 and 402 serial numbers 4001
thru 4334 and 4336 with Elevator PCU part number
390600-1007 and 390600-1009 installed.
Production: The PCU tailstock will be masked to prevent paint overspray
before delivery on DHC-8 Aircraft Models 401 and 402 serial
numbers 4335, 4337 and subsequent.
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.

### Page 4

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 2 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
Spares Affected:
The swaged bearing p/n MS14103-7 assembled in the tail stock end of each
elevator PCU p/n 390600-1007 and 390600-1009 should be checked for
bearing freeplay. A worn or damaged swaged bearing should be replaced
before any spares are put into service.
B. Reason
Problem: Operators of the Q400 aircraft have reported replacement of several
elevator PCU’s p/n 390600-1007 due to worn swaged bearings p/n
MS14103-7 (located in the elevator PCU tailstock). Swaged bearings that
are worn beyond limits may cause airframe vibrations during normal flight.
Cause: Investigation indicates the root cause as being roller wear due to paint
contamination between the bearing roller and bearing liner. Paint
overspray during production assembly may be the cause.
Solution: A freeplay check of each elevator PCU is accomplished to agree with the
Accomplishment Instructions of this service bulletin.
If the freeplay check reveals a PCU swaged bearing to be the cause, the
affected PCU is removed from the aircraft, the bearing in the tailstock of the
PCU is replaced. The reworked PCU (or a serviceable replacement PCU)
is installed back into original location.
C. Description
The procedures in this service bulletin give the instructions to do the tasks that
follow:
- the aircraft is put into a maintenance configuration. All aircraft electrical power is
selected to OFF, MLG lock pins are installed, NG ground lock is engaged,
hydraulic systems pressure is depleted and work stands are set in position around
the elevator
- a freeplay check is accomplished to agree with Option 1 or Option 2 given in the
Procedure part of the ACCOMPLISHMENT INSTRUCTIONS
- If the freeplay is within limits no addition inspection / rework is required
- if the freeplay is more than specified limits the worn bearing p/n MS14103-7 in the
PCU tailstock is replaced
- each reworked PCU (or a serviceable replacement PCU) is installed to original
location

### Page 5

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 3 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
- a bleeding procedure of affected hydraulic system is done (the No. 1, No. 2 and/or
No. 3 system) to agree with related AMM TASK
- an operational test of the elevator control system is done to agree with related AMM
TASK
- access panels are installed
- Close out procedures are done
D. Compliance
Bombardier Inc. highly recommends that the special inspection & rectification
conveyed in this service bulletin be accomplished 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
A breakdown of the man-hours required are given in the table that follows:
TASK MAN-HOURS
Job Set-Up 1.00
Procedure - Part A - Elevator Freeplay Check
Procedure - Part B - Rectification
*1.00
**0.50
***2.50
Test / RTS 1.00
Close-Out 1.00
*t i m er e q u i r e dt od oaP C Uo n - w i n gc h e c k
or
** time required to do a PCU bench check
*** time required to install one replacement PCU

### Page 6

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 4 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
NOTE: Many man hours would be saved if this service bulletin is accomplished
concurrently with service bulletin 84-27-50.
For any on-site labor assistance, please speak with a Fleet Services representative
for a quote. The Fleet Services group can be contacted via the
Q Series Technical Help Desk by telephone at 416-375-4000 or
email at : thd.qseries@aero.bombardier.com
G. Material - Price and Availability
None
H. Tooling - Price and Availability
None
I. Weight and Balance
None
J. Electrical Load Data
Not affected
K. Publications Affected
ModSums Manual PSM 1-84-12..................................
Maintenance Manual PSM 1-84-2................................
L. References
Revision ‘A’ of this service bulletin was prepared to the related data that follows:
PCA 43203 Rev 0 (for internal reference only)

### Page 7

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 5 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
2. MATERIAL INFORMATION
A. Parts Required Per Aircraft
Part Number Quantity
Per Unit
Description Remarks
MS14103-7 One per PCU Swaged Bearing
B. Parts Required to Modify Spares
Refer to table above (if required).
C. Special Tools and Equipment Required
Refer to the Tools & Equipment section in PSM 1-84-2 (AMM) TASK
27-34-01-700-801.
D. Existing Parts Accountability
The following parts may be affected by this service bulletin. Indented parts are
components of the next higher assembly. The quantity (Qty.) column lists the
quantity that may be affected per aircraft for non-indented parts and the quantity
p e rn e x th i g h e ra s s e m b l yf o ri n d e n t e dp a r t s .
Existing
Part Number Description Qty. IC DC
New Part
Number PNC
MS14103-7 Swaged Bearing *A/R B DIS MS14103-7 R
* one bearing per PCU (as required)
IC Interchangeability Code
A Not interchangeable.
B Removed part number and replacement part number are the same.

### Page 8

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 6 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
C Conditionally Interchangeable. Inst allation of superseded part negates the
intent of this service bulletin.
DC Disposition
DIS Discard Part.
MUI Multiple Usage Item: Return to stock if serviceable.
RWK Rework existing part in accordance with this service bulletin.
RWI Rework existing part per .....
SAL Salvage. Return to operator’s stores for salvage consideration.
PNC Part Number Code
N No equivalent Bombardier Inc. part number for reworked part. Indicate on
part that this service bulletin has been accomplished.
R Same part number after rework.
S Superseding or equivalent part number.
X Reworked part and superseding part are functionally and physically
equivalent but not identical.
3. ACCOMPLISHMENT INSTRUCTIONS
A. Job Set-Up
WARNING: REMOVE ALL ELECTRICAL POWER FROM THE AIRCRAFT BEFORE
YOU DO MAINTENANCE. PUT WARNING PLACARDS AT THE
EXTERNAL POWER RECEPTACLE AND IN THE FLIGHT
COMPARTMENT. THIS IS NECESSARY TO PREVENT INJURIES TO
PERSONS AND DAMAGE TO THE EQUIPMENT.
WARNING: BE SURE THAT THE HYDRAULIC PRESSURE IS OFF AND THAT
THERE IS NO PRESSURE IN THE HYDRAULIC SYSTEM. IF YOU DO
NOT DO THIS YOU CAN CAUSE INJURIES TO PERSONS AND
DAMAGE TO THE EQUIPMENT.
(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.

### Page 9

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 7 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
(3) Obey all the hydraulic safety precautions (refer to AMM TASK
29-00-00-910-801).
(4) Remove pressure from the hydraulic systems (refer to AMM TASK’s
29-00-00-863-802 and 29-00-00-863-804).
(5) Placard and select all aircraft electrical power to OFF. Refer to AMM TASK’s
24-00-00-861-802 and 24-00-00-910-801 and obey all relevant WARNINGS and
CAUTIONS.
(6) Position a workstand as required to ga in access to the horizontal elevator.
B. Procedure
PART A - ELEVATOR FREE PLAY CHECK
Option 1 - On Wing
(1) Do an elevator freeplay check to agree with the instruction given in AMM TASK
27-34-01-700-801.
(a) If elevator freeplay is within specified limits no additional inspection or rework
is required and the aircraft may be returned to service (refer to the Close Out
section).
NOTE: Some in-service bearings may be observed with some paint overspray on
the tailstock. The bearings may remain in-service if the elevator freeplay
is within limits specified in AMM TASK 27-34-01-700-801.
(b) If elevator freeplay is more than specified limits and the check reveals a PCU
bearing to be the cause, it will be necessary to replace bearings as required
(refer to PART B - Rectification ).
Option 2 - PCU Bench Check
(1) If the elevator PCU’s have been removed from the aircraft due to another
maintenance action, and if deemed feasible, the radial freeplay in each PCU
tailstock bearing may be measured directly as follows:
(a) Secure the PCU in a suitable fixture. Measure the radial freeplay of each
tailstock bearing using a dial indicator or similar measuring devise.

### Page 10

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 8 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
(b) If the bearing radial freeplay is within 0.0007 inch. (0.018 mm), no
additional inspection or rework is required.
(c) If the bearing radial freeplay is more than 0.0007 inch. (0.018 mm), it will be
necessary to replace the bearing (refer to PART B - Rectification steps (2)
and (3).
PART B - Rectification
(1) Remove suspect PCU(s) to agree with applicable instructions in AMM TASK
27-31-36-000-801.
(2) Replace worn / damaged bearing MS14103-7 to agree with applicable
instructions in AMM TASK 20-10-40-400-802.
(3) Install a serviceable PCU to agree with applicable instructions in AMM TASK
TASK 27-31-36-400-801.
(4) Following replacement of a PCU repeat PART A - ELEVATOR FREE PLAY
CHECK ,Option 1, step 1 to make sure freeplay is within specified limits.
C. Close Out
(1) Make sure all related access panels are installed.
(2) Remove all tools and equipment from the work area.
(3) On completion of this service bulletin, make the following entry in the
appropriate logbooks: “Service Bulletin 84-27-52, “Elevator Control System -
PCU Swaged Bearings Worn - Special Inspection & Rectification” accomplished.
If only part of this Service Bulletin is completed, detail the exact limit of work
completed. Enter component serial numbers if applicable in affected logbooks.

### Page 11

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 9 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
Figure 1
Elevator PCU - Typical
PCU
390600-1007
IN PCU TAILSTOCK
SWAGED BEARING LOCATION
MS14103-7

### Page 12

SERVICE BULLETIN 84-27-52
S.B. 84-27-52
Page 10 of 10
25 May 2010
LS
Revision ‘A’ 05 Mar 2012
This Page Intentionally Blank
2

### Page 13

Jan 2009
SERVICE BULLETIN (SB) - - - RECORD OF INCORPORATION
- - - Q SERIES DASH 8 AIRCRAFT
To : CMDB Focal
Facsimile: (1) 416 375 4538
E- -mai l: cmdb.requests@aero.bombardier .com
From:
Company:
Phone: Extn:
Facsimile: Date:
E- -mai l:
The data that you provide below will help us record the incorporation of this ModSum
and the aircraft effectivity in the maintenance manual.
Operator: Service Bulletin: __________________ Revision: _________
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Aircraft Serial Number: Model Number: Date Bulletin Completed:
Fax this sheet to (1) 416 375 4538 or Email PDF to:
cmdb.requests@aero.bombardier.com

### Page 14

Feb 2009
SERVICE BULLETIN (SB) - - - COMMENT SHEET - - - Q SERIES DASH 8 AIRCRAFT
To : SB Focal (T oronto), Bombardier Aerospace Commercial Aircraft
Phone: (1) 416 375 4078 Facsimile: (1) 416 375 4538
E- -mai l: syed.rizvi@aero.bombardier .com
From:
Company:
Phone: Extn:
Facsimile: Date:
E- -mai l:
Select appropriate box(es) and add comments or suggestions you would like us to know
that may enhance the quality of our service bulletins.
Service Bulletin: Revision: ModSum:
1. PLANNING INFORMATION
V Effectivity V Reason V Description V Compliance
V Approval V Manpower V Material V Weight and Balance
V Electrical Load V T ooling V References V Publications Affected
2. MATERIAL INFORMATION
V Kit Content V Special T ools/Equipment V Parts to Modify Spares
V Consumables V Disposition of Existing Parts V Other
3. ACCOMPLISHMENT INSTRUCTIONS
V J o b S e t --- U p V Procedure V Close- - -Out V Te s t
V Illustration(s) V Other
4. COMMENTS, REMARKS, SUGGESTIONS
Fax this sheet to (1) 416 375 4538 or Email PDF to:
syed.rizvi@aero.bombardier.com

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