1959 deHavilland Way.

Sidney, B.C. Canada V8L 5V5 Tel: (250) 656

- 7227 

# DHC - 2 

# Beaver

29

- April

- 2013 A. S.B. V2/0007 Revision ‘ NC ’ Page 1 of 6 

# ALERT SERVICE BULLETIN

ATA SYSTEM: 5510 NUMBER: V2 / 0007



## I. PLANNING INFORMATION

A. Effectivity
Aircraft Affected: All DHC

- 2 aircraft

.
NOTE: The instructions in this Service Bulletin are only applicable to the systems and parts i nstalled at the time of delivery on the aircraft or as changed by Viking Service Bulletin(s). Before you do this bulletin, examine all STC or equivalent action changes to make sure this bulletin can be completed.



### B. Reason
A DHC

- 2 horizontal s tabilizer atta c h bracket has been found with two (2) MS21042 lock nuts broken. Upon further investigation
, Viking has found a quality issue with the locknuts. (See Figure 3 ).



### C. Description
Some MS21042 Lockn uts have been identified as being affected by a manufacturing iss ue , making them susceptible to premature failure due to cracking

. This issue had previously been ident ified amongst other aircraft manufacturers and corrective action publications had been distributed. The fact that Viking has recently been supplied with a quantity of sub

- quality locknuts
, indicate s that sub

- quality parts continue to be available

. Due to the recent DHC

- 2 horizontal s tabilizer bracket attach lock nut issue, the following inspection / replacement shall be completed for all DHC

- 2 aircraft. SUBJECT: INSPECTION AND/OR REPLACEMENT OF MS21042 LOCKNUT

IN HORIZONTAL STABILIZER (P/N C2TP1A)

### ALERT SERVICE BULLETIN V 2/0007

29

- April

- 2013 A. S.B. V 2 /0007 Revision ‘NC ’ Page 2 of 6 

### D. Compliance
All DHC

- 2 operators shall inspect their aircraft within 48 hours of receiving this Service Bulletin. If MS21042 lock nuts are found, they must be replaced by MS21044 lock nuts before further flight

.


### E. Approval
The technical content of this Service Bulletin has been approved under the authority of Transport Canada Civil Aviation (TCCA) Design Approval Organization (DAO) 04

- V

- 02.



### F. Manpower Approximately 1 hour labour will be required to perform the inspection of the locknuts

. Approximately 12 hours is required i f locknuts must be replaced with new ones

. NOTE: Visual inspection labour may be considerably more if stabilizer assembly must

be removed to properly inspect locknuts.



### G. Weight and Balance

Not affected.



### H. Electrical Load Data
Not affected.



### I. Publicatio ns Affected
None.



### J. References
This Service Bulletin is self

- contained. No additional drawing or documents are required to implement the Accomplishment Instructions. Note: For more information please contact: Viking Air Limited FAX: 250

- 656

- 0673 Technical S upport Telephone Numbers: 1959 de Havilland Way Regional: 250

- 656

- 7227 Sidney, British Columbia North America: 1

- 866

- 49

- ATLAS Canada, V8L 5V5 International: 1

- 800

- 6727

- 6727 technical.support@vikingair.c om

### ALERT SERVICE BULLETIN V 2/0007

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- 2013 A. S.B. V 2 /0007 Revision ‘NC ’ Page 3 of 6 

## II. ACCOMPLISHMENT INSTR UCTIONS

A. Preparing for Inspection

1. Remove tailcone section as per PSM 1

- 2

- 2 Sec. 2.16 ; 2. If visual inspection is impeded in any way, remove stabilizer assembly as per PSM 1

- 2

- 2
, Sec. 2.18.1

.


### B. Inspection Procedures

1. Using a flashlight, visually inspect quantity six (6) lock nuts (as indicated in Figure 1 ) for type installed : a) I f the inst alled locknuts are NOT MS21042 (ref. Figure 2A
, 2B
, 2C for visual aid of possible locknuts installed in this application ) skip to Step II. D; b) If the insta lled locknuts are MS21042 (ref. Figure 2D for visual aid), c ontinue to Step II. C.



### C. Replacement of Affected Locknuts

1. Remove stabilizer assembly as per PSM 1

- 2

- 2
, Sec. 2.18.1;
2. Remove affected locknuts;
NOTE: if locknut is completely missing, inspect area for pieces of broken lock nut to eliminate F oreign O bject D amage (FOD) potential.
3. Install new MS21044 locknuts (IAW para III. A. table) as per standard practices ; NOTE: Ensure a minimum of two (2) threads on the attach bolts are visible when the lock nut is ins talled.



### D. Close

- Out

1. Re

- install stabilizer assembly per PSM 1

- 2

- 2
, Sec. 2.18.3;

2. Re

- install tailcone as per PSM 1

- 2

- 2
, Sec. 2.16.2.

3. Inform Viking Technical Support of any cracked locknut findings (See I.J. References)



### E. Recording
After completion of activities m ake the following entry in the aircraft log book: “Service Bulletin No. V 2 /00 07

– INSPECTION OR INSPECTION/ REPLACEMENT OF MS210 42 LOCKNUT I N HORIZONTAL STABILI ZER (P/N C2TP 1 A ) has been incorporated”.

### ALERT SERVICE BULLETIN V 2/0007

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## III. MATERIAL INFORMATION AND TOOLING

A. Material Information ( Parts Required Per Aircraft)

Old Part No. Replacement Part No.

MS21042

- 3 MS21044N3
MS21042

- 4 MS21044N4



### B. Material Information
None



### C. Tooling

– Price and Availability

 Standard aviation hand tools

 Flashlight

 Mirror

### ALERT SERVICE BULLETIN V 2/0007

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- 2013 A. S.B. V 2 /0007 Revision ‘NC ’ Page 5 of 6 

## IV. DRAWINGS AND TABLES

F IGURE 

### 1

– MS21042 L OCKNUT 

### L OCATION

L OCKNUT LOCATION

### ALERT SERVICE BULLETIN V 2/0007

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- 2013 A. S.B. V 2 /0007 Revision ‘NC ’ Page 6 of 6 

### F IGURE 

### 2 A


### – AN364 L OCKN UT 

### F IGURE 

### 2 B


### – AN 365 L OCKN UT 

### F IGURE 

### 2 C


### – MS21044 L OCKN UT



### F IGURE 

### 2 D


### – MS21042 L OCKN UT 

### (A LERT 

### S ERVICE 

### B ULLETIN 

### S UBJECT 

### )

F IGURE 

### 3

– D ISCREPANT 

### MS21042 L OCKN UT