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DHC---8 (DASH 8)

SERVICE BULLETIN 84---32---140

Landing Gear --- MLG Downlock Stabilizer Brace Lock Link Rigging Change toAddress MLG Unintended Unlocking --- ModSum 4---903379

This page transmits Revision ‘B’ of Service Bulletin 84---32---140, pages 1 thru 10,dated 30 Jan 2018.

This service bulletin is re--- issued in its entirety for the reasons that follow:

--- the Effectivity section is revised to show that the SB is also applicable on aircraftwithout PSEU 30145---0602 installed

--- the Compliance section is revised to add the Transport Canada AD number

--- the References section is revised to convey the latest revision of the servicebulletin and add the Transport Canada Airworthiness AD number.

The Compliance in the previous issue(s) of this service bulletin is not affected bythis revision. No additional rework to the aircraft is introduced by this revision.

Remove the previous revision of Service Bulletin 84---32---140 and attached VSB,and replace with attached.

Previous issue(s) of Service Bulletin 84---32---140:

Initial issue --- Pages 1 thru 10 dated 05 Aug 2016

Revision ‘A’ --- Pages 1 thru 10 dated 12 Jun 2017

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SERVICE BULLETINCustomerSupport

ATA SYSTEM: 3211 NUMBER: 84---32---140

BOMBARDIER AEROSPACE REGIONAL AIRCRAFT CONSIDER THISSERVICE BULLETIN TO BE PARTICULARLY SIGNIFICANT ANDURGE OPERATORS TO PROMPTLY EVALUATE THE CONTENTS

SUBJECT: Landing Gear --- MLG Downlock Stabilizer Brace Lock Link RiggingChange to Address MLG Unintended Unlocking --- ModSum 4---903379

1. PLANNING INFORMATION

A. Effectivity

Aircraft Affected:

In---Service: DHC---8 Aircraft Models 401 and 402 Serial Numbers 4001 and4003 thru 4534 without PSEU 30145---0601 or 30145---0602installed and with any of the MLG brace stabilizer assembliesthat follow installed:

P/N 46400---15 P/N 46400---25P/N 46400---17 P/N 46400---27P/N 46400---21 P/N 46400---29P/N 46400---23

Spares Affected:

None

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B. ReasonProblem: Cases of main landing gear folding soon after landing with the three gear

indicating down and locked have been reported.

Cause: Upon investigation, it was found that the folding of the landing gear wasthe result of extreme vibration levels. These vibrations are subsequentlytransferred through the landing gear resulting in movement in thehorizontal bracewhere theMLGdownlock sensors and downlock actuatorare located. The sensors see a “false reading” (FAR) condition and theSolenoid Sequence Valve (SSV) removes hydraulic pressure from thedownlock actuator.

After further investigation, it was determined that the new Lock Linkovercenter dimension introduced by Service Bulletins 84---32---112 (VSB46400---32---102) or 84---32---120 (VSB 46400---32---109) may havecontributed to the inadvertent landing gear unlocking when impactingforeign objects or encountering excessive vibration levels and downlocksensor reading low inductance when in NEAR position.

Solution: This service bulletin introduces ModSum 4---903379. The modsumreworks the stabilizer brace assembly thru Goodrich service bulletin46400---32---127 to reduce the lock link overcenter and to rig the downlocksensors to smaller target gaps.

C. Description

The procedures in this service bulletin give the instructions to do the tasks that follow:

--- nose landing gear lock is engaged

--- main landing gear doors are opened and locked

--- main landing gear lock pins are installed thru each main gear

--- hydraulic pressure system is depleted

--- aircraft electrical power is removed

--- aircraft is lifted on jacks

--- work platforms or ladders are positioned as required to gain access to the stabilizerbrace in the No. 1 and/or No. 2 wheel well and properly grounded

--- main landing gear lock pins are removed

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--- the proximity sensors are loosened and backed out

--- MLG Stabilizer Brace Assembly is reworked per Goodrich Service Bulletin

--- the proximity sensors are pushed in and tightened

--- rigging and inductance value check of the proximity sensors are done

--- retraction and extension of landing gear is done

--- aircraft is lowered from jacks

--- close out.

D. Compliance

Bombardier Inc. highly recommend incorporation of ModSum 4---903379 at theearliest opportunity unless otherwise directed by the operator’s airworthinessauthority.

Transport Canada Airworthiness Directive CF---2016---31R1 has been issued.

E. Approval

The technical content of this service bulletin has been approved under the authority ofthe Transport Canada Civil Aviation (TCCA) Design Approval Organization No: DAO#93---Q---02.

This service bulletin does not affect Airworthiness Limitations (AWLs) or DamageTolerance Inspections (DTIs).

F. Manpower

It will take an estimated 5.50/6.50* man---hours to complete this service bulletin. Thebreakdown of the man---hours is shown in the table that follows:

TASK MAN---HOURS

Job Set---Up 2.00

Procedure 1.00/2.00*

Test / RTS 2.00

Close---Out 0.50

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*If stop shim is replaced.

This estimate is for direct labour done by an experienced crew and it does notinclude, planning, familiarization, cure time, part fabrication, tool acquisition or losttime.

G. Material --- Price and Availability

Refer to the attached Goodrich Service Bulletin 46400---32---127.

H. Tooling --- Price and Availability

None

I. Weight and Balance

Not affected

J. Electrical Load Data

Not affected

K. Publications Affected

Aircraft Maintenance Manual PSM 1---84---2. . . . . . . . . . . . . . . . . . . . . . . . .

ModSums Manual PSM 1---84---12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

L. References

Revision ‘B’ of this service bulletin was prepared to the related data that follows:

ModSum 4N903379 Rev. ‘D’

ModSum 4---903379 Rev. ‘F’

ModSum 4N168092 Rev. ‘B’

ModSum 4N126651 Rev. ‘C’

ModSum 4N168128 Rev. ‘A’

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Goodrich Service Bulletin 46400---32---127 dated Jul 25/16

Transport Canada Airworthiness Directive CF---2016---31R1

PCA 46055 Revision 0 (for internal reference only)

2. MATERIAL INFORMATION

A. Parts Required Per Aircraft

Refer to the attached Goodrich Service Bulletin 46400---32---127.

B. Parts Required to Modify Spares

None

C. Special Tools and Equipment Required

None

D. Existing Parts Accountability

Refer to the attached Goodrich Service Bulletin 46400---32---127.

3. ACCOMPLISHMENT INSTRUCTIONS

If it is not possible to complete all the instructions of this service bulletin because of theconfiguration of the aircraft, speak with a representative of Bombardier in the CRC at1---844---272---2720 (1---844---CRC---CRC0) or email at thd.qseries@aero.bombardier.comfor analysis and to get an approved disposition to complete this service bulletin.

A. Job Set---Up

(1) Engage the nose gear ground lock (refer to AMM TASK 10---11---00---400---801).

(2) Open and lock the main landing gear doors (refer to applicable instructions inAMM TASK 32---00---00---840---801).

(3) Install the lock pins on the main landing gear (refer to AMM TASK10---11---00---400---802).

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(4) Deplete all hydraulic pressure in the No. 1, No. 2 and No. 3 system (refer toAMM TASK 29---00---00---863---802 and TASK 29---00---00---863---804).

(5) Placard and select all aircraft electrical power to OFF. Obey all relevantWARNINGS and CAUTIONS (refer to AMM TASK 24---00---00---861---802 and24---00---00---910---801).

(6) Install a warning sign on the external hydraulic connection.

(7) Install a warning sign on the hydraulic PTU Control Switch (on main instrumentpanel).

(8) Lift the aircraft on jacks (refer to AMM TASK 07---10---00---582---801).

(9) Set up the work platforms or ladders as required to gain access to main landinggear stabilizer brace assemblies. Make sure the work platforms or ladders areelectrically grounded.

(10) Remove the lock pins on the main landing gear (refer to AMM TASK10---11---00---000---802).

B. Procedure

WARNING: MAKE SURE THAT THERE IS NO PRESSURE IN THE HYDRAULICSYSTEM. IF YOU DO NOT DO THIS YOU CAN CAUSE INJURIES TOPERSONS AND DAMAGE TO THE EQUIPMENT.

(1) Loosen and back out the proximity sensors LGDLK1/2 (RGDLK1/2) (refer toFigure 1 and to applicable instructions in AMM TASK 32---61---06---000---802).

NOTE: Do not remove the proximity sensors.

(2) Push up at the apex of the forward and aft link assemblies to break theovercenter lock position.

(3) Rework the MLG stabilizer brace assembly to agree with all of the details givenin the attached Goodrich Service Bulletin 46400---32---127.

(4) Push in and tighten the proximity sensors LGDLK1/2 (RGDLK1/2) (refer to Figure1 and to applicable instructions in AMM TASK 32---61---06---400---802).

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(5) Check the gap of the LH and RH MLG downlock proximity sensors LGDLK1,LGDLK2, RGDLK1 and RGDLK2 (Refer to Figure 1). The gap should be 0.035 to0.040 inch.

(6) If the sensor gap is not within 0.035 to 0.040 inch, adjust the gap to 0.035 to0.040 inch (refer to the applicable instructions in AMM TASK32---61---06---830---801).

(7) Do a check of the the inductance of the proximity sensors (refer to the applicableinstructions in AMM TASK 32---61---00---280---801).

(8) If the inductance exceeds 8.522 mH, incrementally increase the target gap tobring the inductance to 8.522---8.422mH range. Make sure that the resultantsensor gap is not more than 0.045 inch.

(9) Do a retraction and extension of the landing gear (refer to AMM TASK32---31---00---867---801).

(10) Do a visual check to see that the main landing gear is fully retracted. Make surethat nothing hangs loose, binds or touches the other components. Make surethat there is sufficient clearance around all the components especially betweenthe A---Frame and Stabilizer Brace and the doors are fully closed.

(11) Make sure to re--- identify the stabilizer brace assembly nameplate as describedin the attached Goodrich Service Bulletin 46400---32---127 using the vibropeenmethod.

(12) Repeat above steps (1) to (11) to do the rework on opposite MLG stabilizerbrace.

C. Close Out

(1) Remove all tools and equipment from the work area.

(2) Lower the aircraft from the jacks (refer to AMM TASK 07---10---00---582---801).

(3) Unlock and close the landing gear doors (refer to AMM TASK32---00---00---840---802 ).

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(4) On incorporation of this ModSum make an entry that conforms to localregulatory requirements in the applicable logbook(s). If only part of thisModSum is completed, use only this service bulletin number as reference anddetail exact limit of work completed. Enter component serial numbers ifapplicable. Enter this ModSum number only after complete and functionalincorporation of all work defined in this service bulletin.

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MLG Stabilizer BraceFigure 1

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Jan 2009

SERVICE BULLETIN (SB) --- RECORD OF INCORPORATION--- Q SERIES DASH 8 AIRCRAFT

To: CMDB FocalFacsimile: (1) 416 375 4538E--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 ModSumand 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 AIRCRAFTTo: SB Focal (Toronto), Bombardier Aerospace Commercial Aircraft

Phone: (1) 416 375 4078 Facsimile: (1) 416 375 4538E--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 knowthat 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