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: - the Effectivitysection 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

# 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.

### 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 theACCOMPLISHMENT 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

### 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 * time required to do a PCU on-wing check or ** time required to do a PCU bench check *** time required to install one replacement PCU

### 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)

### 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 per next higher assembly for indented parts.

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.

### 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. Installation 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.

### 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 gain 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 limitsno 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 limitsand 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.

### 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 - Rectificationsteps (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.

### 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

### 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 2Jan 2009 SERVICE BULLETIN (SB) --- RECORD OF INCORPORATION --- Q SERIES DASH 8 AIRCRAFT To: CMDB Focal Facsimile: (1) 416 375 4538 E --mail: cmdb.requests@aero.bombardier.com From: Company: Phone: Extn: Facsimile: Date:

E --mail: 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.comFeb 2009 SERVICE BULLETIN (SB) --- COMMENT SHEET --- Q SERIES DASH 8 AIRCRAFT

To: SB Focal (Toronto), Bombardier Aerospace Commercial Aircraft Phone: (1) 416 375 4078 Facsimile: (1) 416 375 4538 E --mail: syed.rizvi@aero.bombardier.com From: Company: Phone: Extn: Facsimile: Date:

E --mail: 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 VApproval V Manpower V Material VWeight and Balance V Electrical Load V Tooling V References V Publications Affected 2. MATERIAL INFORMATION V Kit Content V Special Tools/Equipment V Parts to Modify Spares V Consumables V Disposition of Existing Parts V Other 3. ACCOMPLISHMENT INSTRUCTIONS V Job Set ---Up V Procedure V Close---Out V Test V Illustration(s) V Other 4. COMMENTS, REMARKS, SUGGESTIONS



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