Page 1 of 2 ATA Ref: 55-10

27 May 2014 Service Bulletin V3/0005

SERVICE BULLETIN TRANSMITTAL SHEET

TRIM JACK MOUNTING BLOCK - HORIZONTAL STABILIZER ACTUATOR - INSPECTION

Service Bulletin No.: V3/0005 Date of Original Issue: 28 February 2013

Revision No.: Revision A Date of Issue: 27 May 2014

This Service Bulletin notifies operators of an issue where the Horizontal Stabilizer Actuator mounting 

block has been found to be loose, and also provides operators with an inspection procedure to 

determine the integrity of the mounting blocks on their aircraft, and an Inspection Reply Form to return to 

Viking Air describing the results of the inspection.

NOTE 1: NO RETROACTIVE ACTION IS REQUIRED ON AIRCRAFT INSPECTED TO THE 

PREVIOUS REVISION OF THIS SERVICE BULLETIN.

NOTE 2: This revision supersedes the previous revision of this Service Bulletin.

NOTE 3: Black change bars in the left margin of this Service Bulletin denote changes from the previous 

revision.

Transmittal Sheet refers to changes made since the previous revision. This Revision is issued to:

1. Improved instructions.

2. Shorten the compliance time.

Previous Revisions of Service Bulletin Number V3/0005:

Initial Issue - Pages 1 thru 6 dated 28-February-2013.
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1959 De Havilland Way 

Sidney, B.C. Canada 

V8L 5V5 

Tel: (250) 656 - 7227 

SERVICE BULLETIN

ATA SYSTEM: 5510 NUMBER: V3/0005

SUBJECT: Trim Jack Mounting Block – Horizontal Stabilizer Actuator - Inspection

I. PLANNING INFORMATION

A. Effectivity

Aircraft Affected: DHC-3 All. 

B. Reason 

The tailplane stabilizer actuator (trim jack) mounting block, (P/N C3FS79-5/-7), was 

found to be loose in the forward-aft and side-to-side directions. The block is fastened 

to channel bracket (P/N C3FS78-18) with three AN456AD6-16 rivets (see Figure 1

for location diagram). The mounting block fastens the stabilizer actuator (trim jack)

which allows the incidence of the stabilizer to be varied. The stabilizer actuator (trim 

jack) also functions as the rear mounting point for the stabilizer.

C. Description 

This Service Bulletin introduces a one-time inspection of the stabilizer actuator (trim 

jack) lower mount block for integrity. Access to the affected area is through an access

door on the port side between STA 427.38 & 444.38. When required, the inspection

instructions may include removal of the stabilizer actuator (trim jack) to check the 

security of the block. Operators are asked to report their findings to the Viking Air 

Limited Technical Support Desk – see Sec. I.J for contact information.

D. Compliance

Unless previously carried out per SB V3/0005 Rev “NC”, operators shall accomplish 

the inspection detailed in this Service Bulletin within 100 flight hours or within 90 days

of the issue date of this Service Bulletin, whichever comes first.

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 (DAO) 

04-V-02. 

DHC-3

Otter

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F. Manpower

An estimated 3 man-hours will be required to complete the inspection activities of 

this Service Bulletin.

G. Weight and Balance 

None.

H. Electrical Load Data 

Not affected. 

I. Publications Affected 

None.

J. References 

This Service Bulletin contains a Survey to be completed and returned to Viking. No 

drawings are supplied. For more information please contact:

Viking Air Limited Technical Support

1959 De Havilland Way

Sidney, British Columbia

V8L 5V5

technical.support@vikingair.com

FAX: 250-656-0673

Telephone Numbers:

Regional: 250-656-7227

North America: 1-800-663-8444

International: 1-800-6727-6727

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II. ACCOMPLISHMENT INSTRUCTIONS

A. INSPECTION PROCEDURE (Ref. Figure 1)

1. Using the hand wheel in the cockpit, wind stabilizer to full nose up position. Visually 

confirm that the trim is fully extended.

2. Remove stabilizer actuator (trim jack) access cover and horizontal stabilizer fairings 

on both sides. Refer to PSM 1-3-2 para. 2.27.1 for access instructions.

3. With stabilizer safely supported:

a. Relieve cable tension in accordance with PSM 1-3-2 para. 2.27.1.d.

b. Remove stabilizer actuator (trim jack) upper attachment bolt being careful not to 

disturb cables.

c. Disengage the upper end of the stabilizer actuator (trim jack) by moving it 

forward or aft away from the upper attachment fitting.

d. Grip the upper end of the stabilizer actuator (trim jack) and lightly attempt to move 

it side-to-side. Grip the lower end of the stabilizer actuator (trim jack) and attempt 

to move it fore and aft as well as up and down with sufficient force to assess 

whether the lower trim jack mount block requires further inspection.

e. With the aid of a bright flash light, mirror or boroscope, visually inspect the 

stabilizer actuator (trim jack) mounting block (P/N C3FS79-5/-7) and the channel 

bracket (P/N C3FS78-18) for:

• Loose, broken, missing or corroded fasteners;

• Fretting, working or wear marks around fastener heads;

• Elongated or corroded fastener holes;

• Cracking or corrosion on the remaining-accessible area of stabilizer 

actuator (trim jack) mounting block (P/N C3FS79-5/-7) and the channel 

bracket (P/N C3FS78-18).

4. If NO motion, looseness, defects or other abnormality is found, reinstall the stabilizer 

actuator (trim jack) upper attachment bolt per 2.27.5.c. Re-apply cable tension in 

accordance with PSM 1-3-2 para. 2.27.5.h. Reassemble the removed access cover 

and horizontal stabilizer fairings

5. If any motion, looseness, defects or other abnormality is detected, remove the 

stabilizer actuator (trim jack) in accordance with PSM 1-3-2 para. 2.27.1 and 

investigate the lower trim jack mount block (P/N C3FS79-5/-7) as well as the mounting 

bracket (P/N C3FS78-18) to find the root cause on the source of motion, looseness 

or defect.

6. If any movement or other abnormality is found, contact Viking Technical Support prior 

to further flight, to report details of the findings and repair options.

7. In all cases, complete the attached survey form and return it to Viking Technical 

Support. 

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B. RECORDING

On completion of this Service Bulletin, make the following entry in aircraft log book: 

“Service Bulletin No. V3/0005 – HORIZONTAL STABILIZER ACTUATOR (TRIM JACK)

– INSPECTION has been incorporated”.

III. MATERIAL INFORMATION AND TOOLING 

A. Material

None

B. Tooling – Price and Availability

(a) Standard aircraft maintenance hand tools

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IV. TABLES AND FIGURES

FIGURE 1 – TRIM JACK MOUNTING BLOCK LOCATION

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Service Bulletin V3/0005 – Operator Reply Form

Operator Name: 

Contact Person: 

Contact Phone/Email: 

A/C Registration No.: A/C Serial No.: 

A/C TTSN: A/C TCSN: 

Inspection Findings:

Additional Comments:

Please return form via email to technical.support@vikingair.com or via fax to 250-656-0673

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