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 References section 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

- the ACCOMPLISHMENT INSTRUCTIONS section 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

D

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

1
Jan 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.com
Feb 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