# Bombardier Service Bulletin 84-32-121

Copy: No revision named ("SB 84-32-121-NC"), 10 pages: PDF https://openairdocs.org/files/sha256/d0/f8/d0f84b643eb8b28ed19c02d78b571de2fcf1fc639f9242232558cbdae4e44600; text https://openairdocs.org/service-documents/bombardier/sb-84-32-121/file/d0f84b643eb8.md. Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2014-0188; AD 2015-02-12 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: 84-32-121
- Page: https://openairdocs.org/service-documents/bombardier/sb-84-32-121

## ADs that cite it (1) (OpenAirDocs)

Newest first, with the revision each names, as OpenAirDocs read it from the AD's text.

- [AD 2015-02-12](https://openairdocs.org/ad/2015-02-12.md), effective Mar 6, 2015: No revision named

Also cited in [1 proposed AD](https://openairdocs.org/service-documents/bombardier/sb-84-32-121/proposed.md).

## Text (10 pages)

Rights: © Bombardier Inc. Filed by the FAA in regulations.gov docket FAA-2014-0188; AD 2015-02-12 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. Some pages are 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

D
S.B. 84- - -32- - -121
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SERVICE BULLETIN
Customer
Support
ATA SYSTEM: 3211 NUMBER: 84- - -32- - -121
BOMBARDIER AEROSPACE REGIONAL AIRCRAFT CONSIDER THIS
SERVICE BULLETIN TO BE PARTICULARL Y SIGNIFICANT AND
URGE OPERATORS TO PROMPTL Y EVALUATE THE CONTENTS
SUBJECT : Landing Gear - - - MLG Stabilizer Brace Assembly - - - Lock Link
Assembly - - - Inspection/Rectification
1. PLANNING INFORMA TION
A. Effectivity
Aircraft Affected:
In- - -Service: DHC- - -8 Aircraft Models 401 and 402 Serial Numbers 4001,
4003 thru 4454.
Production: The gap, torque and lubrication have been verified on
DHC- - -8 Aircraft Serial Numbers 4455 and subsequent per
ModSum 4- - -168098.
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.

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Spares Affected:
None
B. Reason
Problem: An operator was unable to achieve a down and locked indication on one
landing gear.
Cause: Investigation determined the cause as lack of lubrication and possible
over- - -torque of the lock link apex pin retaining bolt.
Solution: This service bulletin provides the instructions to inspect the MLG lock link
assembly to make sure the torque of the lock link apex joint is within the
specified limits and to make sure the stabilizer brace joint is properly
lubricated.
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
- - - nose landing gear lock is engaged
- - - main landing gear lock pins are installed thru each main gear
- - - main landing gear doors are opened and locked
- - - hydraulic pressure system is depleted
- - - aircraft electrical power is removed
- - - work platforms or ladders are positioned as required to gain access to the stabilizer
brace in left and right wheel wells and properly grounded
- - - MLG Stabilizer Brace Assembly lock link apex joint is checked for gap, and if
necessary, lubricated
- - - if lock links need to be retorqued to meet gap requirement, aircraft is lifted on jacks
- - - close out.

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D. Compliance
Bombardier Inc. highly recommends incorporation of this service bulletin at the
earliest opportunity unless otherwise directed by the operator’s airworthiness
authority.
Transport Canada Airworthiness Directive 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
O r g a n i z a t i o n N o : D A O # 9 3 --- Q --- 0 2 .
This service bulletin does not affect Airworthiness Limitations (AWLs) or Damage
T olerance Inspections (DTIs).
F. M a n p o w e r
It will take an estimated 3 man- - -hours to complete this service bulletin. The
breakdown of the man- - -hours is shown in the table that follows:
TASK M A N --- H O U R S
J o b S e t --- U p 0.50
Procedure 2.00
T e s t/R T S 0.00
Close- - -Out 0.50
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 T echnical Help
Desk by telephone at 416- - -375- - -4000 or email at: thd.qseries@aero.bombardier.com
G. Material - - - Price and Availability
None

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H. T ooling - - - Price and Availability
None
I. Weight and Balance
None
J. Electrical Load Data
Not affected
K. Publications Affected
None
L. References
The initial issue of this service bulletin was prepared to the engineering and related
data that follows:
ModSum 4N168098 Rev. ‘B’
ModSum 4- - -168098 Rev. ‘A’
PCA 44512 Revision 0 (for internal reference only)
Goodrich Service Bulletin 46400- - -32- - -111
Transport Canada Airworthiness Directive Pending.
2. MATERIAL INFORMA TION
A. Parts Required Per Aircraft
None
B. Parts Required to Modify Spares
None
C. Special T ools and Equipment Required
None
D. Existing Parts Accountability
None

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3. ACCOMPLISHMENT INSTRUCTIONS
A . J o b S e t --- U p
(1) Engage the nose gear ground lock (refer to AMM TASK 10- - -11- - -00- - -400- - -801).
(2) Install the lock pins on the main landing gear (refer to AMM TASK
10- - -11- - -00- - -400- - -802).
(3) Open and lock the main landing gear doors (refer to applicable instructions in
AMM TASK 32- - -00- - -00- - -840- - -801).
(4) Deplete all hydraulic pressure in the No. 1, No. 2 and No. 3 system (refer to
AMM 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 relevant
W A R N I N G S a n d C A U T I O N S ( r e f e r t o A M M T A S K 2 4 --- 0 0 --- 0 0 --- 8 6 1 --- 8 0 2 a n d
TASK 24- - -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 instrument
panel).
(8) Set up the work platforms or ladders as required to gain access to main landing
gear stabilizer brace assemblies (refer to Figure 1). Make sure the work
platforms or ladders are electrically grounded.
B. Procedure
WARNING: MAKE SURE 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) Inspect the stabilizer brace lock link apex joint in accordance with the
instructions given in SECTION II - - - ACCOMPLISHMENT INSTRUCTIONS of
attached Goodrich Service Bulletin 46400- - -32- - -111.

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(2) If gap is 0.001 inch (0.025 mm) or greater, continue with step (4).
(3) If gap is less than 0.001 inch (0.025 mm), do as follows (refer to Figure 2):
(a) Lift aircraft on jacks (refer to applicable instructions in AMM TASK
07- - -10- - -00- - -582- - -801).
(b) Remove and discard cotter pin MS24665- - -155.
(c) Loosen nut MS14145L4 at bolt NAS6204- - -32D on MLG Stabilizer Brace.
NOTE: Loosen nut to zero torque. Do not remove nut MS14145L4 from
bolt NAS6204- - -32D.
CAUTION: DO NOT EXCEED MAXIMUM TORQUE VALUE OF 30 LBF IN
(3.4 NM). IF MAXIMUM TORQUE IS EXCEEDED THE LOCK
LINK FUNCTION MAY BE AFFECTED.
(d) T orque nut MS14145L4 to 20 lbf in (2.3 Nm) and continue to tighten nut to
achieve cotter pin alignment.
NOTE: T o r q u ev a l u ei si na d d i t i o nt or u no nt o r q u e .
NOTE: If maximum torque value is obtained before cotter pin alignment,
loosen nut until alignment is achieved.
NOTE: It is permissible to use washer NAS1149C0416R in lieu of washer
NAS1149C0432R under the nut to aid in cotter pin alignment.
(e) Inspect lock link apex joint for clearance. If clearance is still less than 0.001
inch (0.025 mm), contact T echnical Help Desk by telephone at 416- - -375- - -4000
or email at thd.qseries@aero.bombardier.com for approved disposition/action.
(f) If clearance is 0.001 inch (0.025 mm) or greater, install cotter pin
MS24665- - -155.
(g) Make sure LH and RH target bracket assemblies are secure.
(h) Confirm proximity/target gap is within limits (refer to CMM 32- - -11- - -04
ASSEMBL Y). If gap is not within limits, adjust the proximity sensor (refer to
applicable instructions in AMM TASK 32- - -61- - -06- - -830- - -801).

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(i) Lower the aircraft and remove the jacks (refer to applicable instructions in
AMM TASK 07- - -10- - -00- - -582- - -801).
(4) Lubricate the stabilizer brace lock link apex joint (refer to applicable instructions
in AMM TASK 12- - -20- - -01- - -640- - -803).
(5) Vibro- - -peen accomplishment of Goodrich Service Bulletin 46400- - -32- - -111 and
date accomplished in MOD STATUS field of nameplate.
(6) Repeat steps (1) to (5) for the opposite stabilizer brace lock link apex joint.
C. Close Out
(1) Remove all tools and equipment from the work area.
(2) Unlock and close the landing gear doors (refer to AMM TASK
3 2 --- 0 0 --- 0 0 --- 8 4 0 --- 8 0 2 ) .
(3) On completion of this service bulletin, make the following entry in the
appropriate logbooks: “Service Bulletin 84- - -32- - -121 (i.e. Landing Gear - - - MLG
Stabilizer Brace Assembly - - - Lock Link Assembly - - - Inspection/Rectification)
accomplished.”

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MLG Stabilizer Brace Assembly - - - Location
Figure 1
AREA OF INSPECTION/RECTIFICATION

### Page 9 (OCR)

SERVICE BULLETIN 84-32-121
B
FWD LOCK LINK
PARTIAL SECTION A - A
STABILIZER BRACE
RE TARGET
LH TARGET BRACKET ASSEMBLY  BRACKET ASSEMBLY
BOLT
NAS6204-32D  WASHER
NAS1149C0432R
LOCK PIN APEX PIN  NUT
MS14145L4
COTTER PIN
MS24665-155
AFT LOCK LINK
NOTE  PARTIAL SECTION B - B
/1 PUSH AFT LOCK LINK TO ONE SIDE. MINIMUM GAP 0.001 IN. (0.025 MM).
Lock Link Apex Joint - Gap Check
Figure 2
27 May 2013  S.B. 84-32-121
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