# Bombardier Service Bulletin 84-32-74 Copy: Revision A ("U.S. DOT/FAA - Service Bulletin"), 20 pages: PDF https://openairdocs.org/files/sha256/b3/53/b3537e2a1f58001e547e72903a7613361b9929c2bc1a058eae6d733fbe798eed; text https://openairdocs.org/service-documents/bombardier/sb-84-32-74/file/b3537e2a1f58.md. Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2011-0470; AD 2011-17-04 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: 84-32-74 - Latest revision known: 84-32-74, Revision A, dated May 17, 2010 (OpenAirDocs) - Page: https://openairdocs.org/service-documents/bombardier/sb-84-32-74 ## ADs that cite it (2) (OpenAirDocs) Newest first, with the revision each names, as OpenAirDocs read it from the AD's text. - [AD 2012-20-09](https://openairdocs.org/ad/2012-20-09.md), effective Nov 20, 2012: Revision A - [AD 2011-17-04](https://openairdocs.org/ad/2011-17-04.md), effective Sep 19, 2011: Revision A Also cited in [1 proposed AD](https://openairdocs.org/service-documents/bombardier/sb-84-32-74/proposed.md). ## Text (20 pages) Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2011-0470; AD 2011-17-04 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. This text is OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 (OCR) DHC-8 (DASH 8) SERVICE BULLETIN 84-32-74 Landing Gear - Aft Main Landing Gear Door Bump Plate - Rework By Trimming Edge - ModSum 4-113645 This page transmits Revision 'A' of Service Bulletin 84-32-74, pages 1 thru 16 dated 17 May 2010. This service bulletin is re-issued in its entirety for the reasons that follow: - the Description section is revised to reflect changes in the Accomplishment Instructions - the Compliance section is revised to add a Note - the Manpower section is revised to include additional time required to raise and lower the aircraft and to do an operational check of the landing gear alternate extension system - the References section is revised to convey the latest revision of the service bulletin and engineering documentation - the MATERIAL INFORMATION section is revised to correct material information. Was Type I Class B Sealant PR 1776M B2, now Type I Class A Sealant PR 1422 A2 - the Job Set-Up part of the ACCOMPLISHMENT INSTRUCTIONS section is revised as follows: added step (6). The new step gives the instruction to raise the aircraft on jacks - the Procedure part of the ACCOMPLISHMENT INSTRUCTIONS section is revised as follows: step (2), (6) and the NOTE after (6) are revised to make editorial changes step (5) is revised to do a detailed visual inspection of the bump plate in lieu of an Eddy Current inspection step (9) is deleted. The requirement to fillet seal between base plate and bumper plate no longer required Revision 'A' 17 May 2010 ### Page 2 (OCR) - the Close Out part of the ACCOMPLISHMENT INSTRUCTIONS section is revised as follows: added new steps (1) and (2). New step (1) gives the instruction to do an operational check of the landing gear alternate extension system. Step (2) gives the instruction to lower the aircraft. The Compliance in the previous issues of this service bulletin is not affected by this revision. Additional rework to the aircraft is introduced by this revision. Remove Service Bulletin 84-32-74 Initial Issue dated 23 Dec 2009 and replace with attached. Previous issues of Service Bulletin 84-32-74: Initial issue(s) - Pages 1 thru 16 dated 23 Dec 2009 ### Page 3 (OCR) de HAVILLAND BOMBARDIER DASH8 SERVICE BULLETIN Customer Support ATA SYSTEM: 3212 NUMBER: 84-32-74 BOMBARDIER AEROSPACE REGIONAL AIRCRAFT CONSIDER THIS SERVICE BULLETIN TO BE PARTICULARLY SIGNIFICANT AND URGES OPERATORS TO PROMPTLY EVALUATE THE CONTENTS SUBJECT: Landing Gear - Aft Main Landing Gear Door Bump Plate - Rework By Trimming Edge - ModSum 4-113645 1. PLANNING INFORMATION A. Effectivity Aircraft Affected: In-Service: DHC-8 Aircraft Models 401 and 402 Serial Numbers 4001 thru 4247. 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 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 1 of 16 LS ### Page 4 (OCR) SERVICE BULLETIN 84-32-74 B. Reason Problem: An operator of the Q400 aircraft has reported a recent incident in which the right hand main landing gear (MLG) on one aircraft failed to extend using the alternate gear extension system. The MLG retracted normally following takeoff, however during climb the gear door light illuminated momentarily. The aircraft continued to its destination and the Quick Reference Handbook (QRH) was checked and it was decided to perform an alternate gear extension. After repeated unsuccessful attempts to extend the gear with the alternate system, the gear was extended using the normal hydraulic system and the aircraft landed uneventfully. Cause: Investigation determined that a lip on bump plate 85424082-101 & - 103, located on the outboard main landing gear door, had snagged in the tread groove on one of the tires preventing the doors from opening and the gear from free falling to the extended position (refer to view on Figure 1). Solution: This service bulletin introduces ModSum 4-113645. The ModSum trims the edge of bump plate 85424082 to enlarge the chamfer thus eliminating the possibility of snagging in the tread groove. 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, the aircraft is raised on jacks and work stands are set in position - the bump plate in each nacelle is located and trimmed to form a smooth transition radius (0.25 inch. min.) - each bump plate is checked for cracks then treated with alodine, primed using epoxy chromate primer and finished with a coat of polyurethane enamel - each bump plate is re- identified with a new part number using an indelible marker - deleted - an operational check of the landing gear alternate extension system is done - all tools and equipment are removed - log book entries are made and the aircraft is returned to service. 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 2 of 16 I LS ### Page 5 (OCR) SERVICE BULLETIN 84-32-74 D. Compliance Bombardier Inc. recommends incorporation of ModSum 4-113645 at the earliest opportunity unless otherwise directed by the operator's airworthiness authority. NOTE: Any operators that have reworked Bumper Plate p/n 85424082-101 and / or 85424082-103 to agree with RD 8/4-54-553 Issue 1 or latter and do the additional tasks that follow will be considered an acceptable alternate means of compliance to this service bulletin. - re-identify each bump plate to agree with ACCOMPLISHMENT INSTRUCTIONS, B. Procedure, step (8)) - do an operational check of the landing gear alternate extension system at earliest opportunity to agree with ACCOMPLISHMENT INSTRUCTIONS, C. Close Out section step (1). 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. This Service Bulletin does not affect Airworthiness Limitations (AWLs) or Damage Tolerance Inspections (DTIs). F. Manpower It will take an estimated 5.5 or 7.5 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 1.50 Procedure 2.00 or 4.00* Test / RTS 0.50 Close-Out 1.50 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 3 of 16 LS ### Page 6 (OCR) SERVICE BULLETIN 84-32-74 * additional time required if bump plate is detached from the base fitting to do the rework 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 The material(s) detailed in Paragraphs) 2.A. may be either furnished or fabricated from the operator's existing stock, purchased as single items from Bombardier Aerospace Regional Aircraft or purchased directly from industry sources. DK parts are to be manufactured and approved locally (refer to disclaimer in the related text or illustration). In some cases, an equivalent to the DK part may be available from Bombardier. H. Tooling - Price and Availability None Weight and Balance None Electrical Load Data Not affected K. Publications Affected Dash 8 Illustrated Parts Catalogue .................... PSM 1-84-4 ModSums Manual .......... ............ PSM 1-84-12 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 4 of 16 LS ### Page 7 (OCR) SERVICE BULLETIN 84-32-74 References The initial issue of this service bulletin was prepared to the engineering drawings and related data that follows: DRAWING SHEET REV 8DK4161 1 ModSum 4Q113645 Rev. 'B' ModSum 4-113645 Rev. 'B' PCA 42626 Revision 2 (for internal reference only) All Operator Message 321 RD8/4-54-553 Issue 4. 2. MATERIAL INFORMATION A. Parts Required Per Aircraft (1) The following material(s) are required for the completion of this service bulletin and 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 Consumable Products Manual PSM 1-84-18. Part Number Qty. Per Aircraft Description Remarks DHMS S3.01 8 oz. Type I Class A PR 1422 A2 Sealant DHMS C4.01 8 oz. Epoxy Primer Type 2 MIL-C-5541 8 oz. Alodine 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 5 of 16 LS ### Page 8 (OCR) SERVICE BULLETIN 84-32-74 Part Number Qty. Per Aircraft Description Remarks DHMS C4.04 8 oz. Polyurethane Type 4 White enamel B0205017AD5-9S Rivet Req'd if bump plates removed for rework NOTE: This service bulletin is self-contained (illustrated). No drawings will be supplied. B. Parts Required to Modify Spares None C. Special Tools and Equipment Required None 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 New Part Part Number Description Qty. IC I DC Number PNC 85424082-101 Bump Plate 1 C RWK 8DK4161 - 101 85424082-103 Bump Plate 1 RWK 8DK4161 - 103 IC Interchangeability Code A Not interchangeable. B Removed Part. No direct replacement. C Conditionally Interchangeable. Installation of superseded part negates the intent of this service bulletin. 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 6 of 16 LS ### Page 9 (OCR) SERVICE BULLETIN 84-32-74 DC Disposition DIS Discard Part. MU Multiple Usage Item: Return to stock it 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 Part number after rework. S Superseding or equivalent part number. Reworked part and superseding part are functionally and physically equivalent but not identical. 3. ACCOMPLISHMENT INSTRUCTIONS A. Job Set-Up WARNING: MAKE SURE THAT ALL HYDRAULIC AND ELECTRICAL POWER IS OFF. MAKE SURE THAT LOCKPINS ARE INSTALLED IN THE DOOR MECHANISMS AND THE MAIN LANDING GEAR BEFORE YOU DO MAINTENANCE IN THE MAIN GEAR WHEEL. THE DOOR MECHANISMS CAN ACCIDENTLY CLOSE AND THE LANDING GEAR CAN ACCIDENTLY RETRACT. INJURY TO PERSONNEL AND/OR DAMAGE TO EQUIPMENT CAN OCCUR. (1) Placard and select all aircraft electrical power to OFF. Obey all relevant WARNINGS and CAUTIONS (refer to AMM TASK'S 24-00-00-861-802 and 24-00-00-910-801). (2) Make sure that lock pins are installed thru each main gear and main gear door mechanism. (3) Make sure the nose gear ground lock is engaged. (4) Install the safety devices and/or warning signs on the landing gear controls and the external hydraulic connection. 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 7 of 16 ILS ### Page 10 (OCR) SERVICE BULLETIN 84-32-74 (5) Make sure that hydraulic pressure in the No.1, 2 and 3 system are depleted (refer to AMM TASK's 29-00-00-863-802 and 29-00-00-863-804). (6) Lift the aircraft on the jacks (refer to AMM TASK 07-10-00-582-801). (7) Set up the work platforms or ladders as required to gain access to the bump plate attached to the aft left MLG door in each nacelle (refer to Figures 2 and 3). B. Procedure (1) Gain access to the bump plate 85424082-101 or (-103) attached to the aft left MLG door in each nacelle and identify the edge to be reworked (refer to Figures 3 and 4). Carefully rework edge of bump plate 85424082 (as required) to agree with the Notes and detail views shown on Figure 4 & 5. Take care not to damage base fitting 85424081 - 101. NOTE: If additional workspace is required, carefully remove the rivets and separate the bump plate from the base fitting before trimming the edge, then rework on a bench. (3) Deburr / break and remove all sharp edges. Ensure a smooth transition radius (0.25 inch. min.) as shown on Figure 5. (5) Do a detailed visual inspection of the bump plate and base fitting using a 10X magnification lens and adequate lighting. Make sure that there are no obvious signs of damage or cracks. Replace damaged or cracked part. (6) Treat bared metal using alodine and prime using epoxy primer (DHMS C4.01) to agree with applicable instruction in PSM 1-84-3 Chapter 51-21-10 and 51-25-10. NOTE: If the bump plate 85424082 was removed to gain access to rework the edge, fay seal mating surface(s) using DHMS S3.01/A2 then install to base fitting 85424081 using rivets B0205017AD5-9S (refer to Figure 6 and applicable instructions in PSM 1-84-3 TASK 51-42-05-02-01 and 51-23-00-00-01). Apply a layer of white polyurethane enamel (DHMS C4.04) over all new primer (refer to Structural Repair Manual PSM 1-84-3 Task 51-25- 15). 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 8 of 16 LS ### Page 11 (OCR) SERVICE BULLETIN 84-32-74 (8) Re-identify each bump plate using an indelible marker as follows: (a) Was 85424082-101. Now 8DK4161-101. (b) Was 85424082-103. Now 8DK4161-103. (9) Deleted. C. Close Out (1) Do an operational check of the landing gear alternate extension system (refer to PSM 1-84-2 TASK 32-34-00-710-801 (2) Lower the aircraft (refer to AMM TASK 07-10-00-582-801). (3) Remove all tools, equipment and unwanted materials from the work area. (4) On incorporation of this ModSum, make an entry that conforms to local regulatory requirements in the applicable logbooks). Enter component serial numbers if applicable. Enter this ModSum number only after complete and functional incorporation of all work defined in this service bulletin. THE DESIGN OF THE PART IN THIS DRAWING HAS BEEN APPROVED BY DE HAVILLAND INC. FOR MANUFACTURE BY OR ON BEHALF OF THE RECIPIENT. THE RECIPIENT IS RESPONSIBLE FOR (A) PROPER MANUFACTURE OF THE PART USING THE SPECIFIED MATERIALS AND FOR INCORPORATION OF THE MODIFICATION, ALL IN ACCORDANCE WITH THE DRAWING AND RELATED INSTRUCTIONS, AND (B) PPROVAL OF THE FINAL INSTALLATION BY THE RELEVANT AIRWORTHINESS AUTHORITY. DE HAVILLAND INC. AND BOMBARDIER INC BOMBARDIER AEROSPACE REGIONAL AIRCRAFT) DISCLAIM ANY RESPONSIBILITY FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES INCLUDING WITHOUT LIMITATION LOSS OR USE, LOSS OF REVENUE OR LOSS OF PROFIT, ARISING FROM SUCH MANUFACTURE, INCORPORATION AND INSTALLATION. 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 9 of 16 LS ### Page 12 (OCR) SERVICE BULLETIN 84-32-74 BUMP PLATE CAUGHT IN TIRE TREAD Figure 1 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 10 of 16 LS ### Page 13 (OCR) SERVICE BULLETIN 84-32-74 Locator View Figure 2 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 11 of 16 LS ### Page 14 (OCR) SERVICE BULLETIN 84-32-74 (85424082-101/-103 ELMP FLATE) (85424081-101 BASE FITTING) -HINGE LINE Y201D -15.05 B LKG DOWN ON LHS AFT MLG DOOR 201L X201D RHS OPPOSITE 183. 71 192. 50 Z2010 -35.65 HINGE LINE -Z201D -38.17 (E.O.P.) - (85424003) VIEW A LKG INBD ON LHS AFT MLG DOOR RHS OPPOSITE Figure 3 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 12 of 16 LS ### Page 15 (OCR) SERVICE BULLETIN 84-32-74 (85424082-101/-103 BUMP PLATE) - DETAIL C ~ (85424081-101 BASE FITTING) SECTION B-B THE DESIGN OF THE PART IN THIS DRAWING HAS BEEN APPROVED BY DE HAVILLAND INC. FOR MANUFACTURE BY OR ON BEHALF OF THE RECIPIENT. THE RECIPIENT IS RESPONSIBLE FOR (A) PROPER MANUFACTURE OF THE PART USING THE SPECIFIED MATERIALS AND FOR INCORPORATION OF THE MODIFICATION, ALL IN ACCORDANCE WITH THE DRAWING AND RELATED INSTRUCTIONS, AND (B) ARUDANE AND PACE RESUNGS SA OSE 1055 OF REVENUE OR DES OF PROFIT ANTING ROM SUCH MANUFACTURE. INCORPORATION AND INSTALLATION. Figure 4 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 13 of 16 LS ### Page 16 (OCR) SERVICE BULLETIN 84-32-74 - (85424082-101/-103 BUMP PLATE) - R . 25 MIN. TANGENT POINT (85424081-101 BASE FITTING) DETAIL C BEFORE PERFORMING REWORK ENSURE EXISTING BUMP PLATE 85424082-101 OR -103 DOES NOT ROTRUDE PAST TANGENT POINT OF BASE FITTIN BATE YARNERO PACES V TH REMON IF BUMP PLATE DOES PROTUDE TRIM THE EXCESS MATERIAL INSTRUCTIONS. Figure 5 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 14 of 16 ILS ### Page 17 (OCR) SERVICE BULLETIN 84-32-74 DO NOT SCALE DRAWING XBB= Rivet B0205017AD5-9S (85424082-101/-103 BUMP PLATE) (85424081-101 BASE FITTING) - VIEW REFERENCE ONLY SHOWING EXISTING FASTENERS Figure 6 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 15 of 16 LS ### Page 18 (OCR) SERVICE BULLETIN 84-32-74 This Page Intentionally Blank 23 Dec 2009 S.B. 84-32-74 Revision 'A' 17 May 2010 Page 16 of 16 ILS ### Page 19 (OCR) BOMBARDIER SERVICE BULLETIN (SB) - RECORD OF INCORPORATION - Q SERIES DASH 8 AIRCRAFT To: Partner Data Co-Ordinator (Toronto), Bombardier Aerospace Commercial Aircraft Phone: (1) 416 375 3534 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.com Jan 2009 ### Page 20 (OCR) BOMBARDIER 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 boxes) 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 • Effectivity • Reason • Description • Compliance • Approval • Manpower • Material • Weight and Balance • Electrical Load • Tooling • References • Publications Affected 2. MATERIAL INFORMATION • Kit Content • Special Tools/Equipment • Parts to Modify Spares • Consumables • Disposition of Existing Parts • Other 3. ACCOMPLISHMENT INSTRUCTIONS • Job Set-Up • Procedure • Close-Out • Test • Illustration(s) • Other 4. COMMENTS, REMARKS, SUGGESTIONS Fax this sheet to (1) 416 375 4538 or Email PDF to: syed.rizvi@aero.bombardier.com Feb 2009 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain, except the copies of manufacturers’ service documents, which belong to their rights holders.