Revision ‘A’ 17 Dec 2012 DHC-8 (DASH 8) SERVICE BULLETIN 8-32-173 Landing Gear - Special Inspection and Rectification - Alternate Downlock Indication System This page transmits Revision ‘A’ of Service Bulletin 8-32-173 pages 1 thru 10 dated: 17 Dec 2012. This service bulletin is re-issued in its entirety for the reasons that follow: - the Compliance section is revised - the Referencessection is revised to convey the latest revision of the service bulletin and engineering documentation - the Parts Required Per Aircraft section has been revised to show Light Blocking Card instead of Business Card - theACCOMPLISHMENT INSTRUCTIONSsection has been revised to show the correct circuit breaker in 3.A.(4) added a Note stating that paragraph 3.B.(2) is only applicable for aircraft that have Mod 8/0534 (SB 8-32-41) installed and added Figure 3 - Figures 1 & 2 have been revised to add arrow showing forward The Compliance in the previous issue(s) of this service bulletin is not affected by this revision. No additional rework to the aircraft is introduced by this revision. Remove the previous issue of Service Bulletin 8-32-173 and replace with attached. Previous issue(s) of Service Bulletin 8-32-173: Initial issue - Pages 1 thru 8 dated 28 Oct 2011

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S.B. 8-32-173 Page 1 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR 

# SERVICE BULLETIN Customer Support
ATA SYSTEM: 3210 NUMBER: 8-32-173 

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

SUBJECT: Landing Gear - Special Inspection and Rectification - Alternate Downlock Indication System

1. PLANNING INFORMATION A. Effectivity Aircraft Affected: In-Service: DHC-8 Aircraft Models 102, 103, 106, 201, 202, 301, 311, 314 and 315 Serial Numbers 003 thru 672. 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 B. Reason Problem: Potential for the landing gear alternate downlock indication system to provide a false ‘‘down and locked” indication. Cause: In conjunction with a reported case of NLG collapse on landing, a review of the alternate downlock indicating system was carried out. The review has revealed that the system can provide a false “down and locked” indication due to a wiring fault. This was not the cause of the reported NLG collapse.

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 2 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR Solution: This Special Inspection and Rectification Bulletin provides a functional check procedure for the NLG and MLG landing gear alternate indication phototransistors. C. Description The procedures in this service bulletin give the instructions to do the tasks that follow: - aircraft is put into standard configuration for maintenance - aircraft electrical power is removed - the nose landing gear lock is engaged - the main landing gear lock pins are installed thru each main gear and main gear door mechanism - electrical power is applied to the aircraft - circuit breakers are closed as required - an operational test is done to verify that the three indicator lights are operational - a light blocking card is inserted between the sensor and the light source of the LH /RH MLG and NLG - fault confirmation of the indicator lights for the LH MLG, RH MLG and NLG in the the Landing Gear Alternate Extension door in the flight compartment floor is done - malfunctioning alternate indication system components are removed and replaced as required - close out. D. Compliance Bombardier Inc. recommends this Special Inspection and Rectification Bulletin be done at the earliest opportunity unless otherwise directed by the operator’s airworthiness authority. A Transport Canada Airworthiness Directive is pending. 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).

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 3 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR F. Manpower It will take an estimated 3.0 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 1.00 Procedure 1.00 Test / RTS 0.00 Close-Out 1.00 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 None
L. References Revision ‘A’ of this service bulletin was prepared to the related data that follows: PCA 6824 Revision 0 (for internal reference only) A Transport Canada Airworthiness Directive is pending.

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 4 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR A. Parts Required Per Aircraft (1) The following material is 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.

Description Qty. Per Aircraft Remarks Light Blocking Card As Required see Note below

NOTE: The light blocking card may consist of any object that is opaque (eg. credit card, business card).
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) Apply electrical power to the aircraft. Refer to AMM PSM 1-8-2, Chapter 12-00-05, PSM 1-82-2, Chapter 12-00-05 or PSM 1-83-2, Chapter 12-00-05. (4) Close the following circuit breaker: RIGHT DC (ESSENTIAL), L6-LDG GEAR-EMER DLK IND.

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 5 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR B. Procedure (1) Carry out the following Alternate Landing Gear Downlock Indicator System test on the Main Landing Gear as follows: (a) Open Landing Gear Alternate Extension door in flight compartment floor and select the landing gear alternate downlock indication (3262-S1) switch to the ON position. Make sure that all three Alternate downlock indicator lights come ON. Refer to Figure 3. (b) With the three Alternate downlock lights ON, block the Left Main Landing Gear Alternate Downlock Sensor with a light blocking card. Refer to Figure 1. Make sure that the Left MLG (3262-DS2) downlock indicator light goes OFF. (c) If the light goes OFF, no further action is required. Proceed to step (g) and do the test of the Right Hand Main Landing Gear Alternate Downlock indication system. (d) If the Light remains ON, remove electrical power from the aircraft and replace the malfunctioning (3262-Q1) phototransistor sensor or harness for the Left MLG Alternate downlock indication system. After the phototransistor or harness has been replaced, repeat the test procedure steps (b) to (c) and make sure the light goes OUT when the sensor is blocked. (e) If light remains ON, replace the card assembly of the Alternate Downlock Indicator Control Unit and repeat steps (b) & (c). (f) If light remains ON, contact Technical Help Desk (THD) for further instructions. (g) With the three Alternate downlock indicator lights ON, block the RH Main Landing Gear Alternate Downlock Sensor with a light blocking card. Refer to Figure 1. Make sure that the RH MLG (3632-DS4) downlock indicator light goes OFF. (h) If the light goes OFF, no further action is required. Proceed to step 2(a) and do the test of the Nose Landing Gear Alternate Downlock Indication System. (i) If the light remains ON, remove electrical power from the aircraft and replace the malfunctioning (3262-Q1) phototransistor sensor or harness for the RH MLG Alternate indication system. After the phototransistor sensor or harness has been replaced, repeat the test procedure steps (g) & (h) and make sure the light goes OFF when the sensor is blocked. (j) If light remains ON, replace the card assembly of the Alternate Downlock Indicator Control Unit and repeat steps (g) & (h). (k) If light remains ON, contact Technical Help Desk (THD) for further instructions.

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 6 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR (2) Carry out the Alternate Landing Gear Downlock Indicator System test on the Nose Landing Gear as follows: (Note: this step is only applicable for aircraft that have Mod 8/0534 SB 8-32-41 installed) (a) Select Alternate indicator landing gear downlock indication (3262-S1) switch to the ON position. Make sure that all three Alternate downlock indicator lights come ON. (b) With the three Alternate downlock indicator lights ON, block the Nose Landing Gear Alternate Downlock Sensor with a light blocking card. Refer to Figure 2. Make sure that the NLG (3262-DS3) downlock indicator light goes OFF. (c) If the light goes OFF, no further action is required. Proceed to Close Out section. (d) If the light remains ON, remove electrical power from the aircraft and replace the malfunctioning (3262-Q2) sensor or harness for the NLG Alternate downlock indicator system. After the phototransistor sensor or harness has been replaced, repeat the test procedure steps (b) & (c) and make sure the light goes OUT when the sensor is blocked. (e) If light remains ON, replace the card assembly of the Alternate Downlock Indicator Control Unit and repeat steps (b) & (c). (f) If light remains ON, contact Technical Help Desk (THD) for further instructions.
C. Close Out (1) Remove all tools and equipment from the work areas. (2) On completion of this service bulletin, make the following entry in the appropriate logbooks: “Service Bulletin 8-32-173 Landing Gear - Emergency Downlock Indication System - Special Inspection and Rectification accomplished.”

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 7 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR LH and RH Main Landing Gear Insertion Locations Figure 1

FWD

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 8 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR Nose Landing Gear Card Insertion Location Figure 2 FWD

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 9 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR Figure 3 Switch and Lights Location SWITCH 3262-S1 LH MLG Light 3262-DS2

RH MLG Light 3262-DS4

NLG Light 3262-DS3

### SERVICE BULLETIN 8-32-173

S.B. 8-32-173 Page 10 of 10 28 Oct 2011 Revision ‘A’ 17 Dec 2012 JR 

### This Page Intentionally Blank 1Jan 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 V Approval V Manpower V Material V Weight 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



## Fax this sheet to (1) 416 375 4538 or Email PDF to: syed.rizvi@aero.bombardier.com