# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 1 of 9 2008-04-14 

## Rotor Flight Control – Cyclic Controls – Modification of Cyclic-StickLocking Device/-Centering Device 1. Planning Information A. Effectivity (1) Helicopters affected: All MBB BK117 C-2, S/N 9004 up to and including S/N 9230. (2) Components affected: Cyclic Stick Locking Device B856M1011101 Pin L311M1038205 or L311M1099205 (3) Spare Parts affected: See 1.A.(2). B. Concurrent Requirements Immediately after accomplishment of this Alert Service Bulletin the pilots must be informed of its content and their attention must be drawn to the following: NOTE Before starting the engines, the cyclic stick (1, Figure 3) must be moved to its neutral position. By folding up cantilever (5) to pin (3) it is possible to move the cyclic stick (1) into its neutral position and to center it. A locking of the cyclic stick (1) is no longer possible. C. Reason There have been several cases where lift-off of a helicopter was executed with a locked cyclic stick. A locked cyclic stick may lead to a loss of controllability of the helicopter. In order to prevent an inadvertent lift-off of the helicopter with a locked cyclic stick, a modification of the cyclic stick cantilever is accomplished with this Alert Service Bulletin. After accomplishment of this modification the cyclic stick can only be centered in its neutral position. A locking of the cyclic stick is no longer possible. D. Description Remove slide and spring from cyclic stick cantilever. E. Compliance This Alert Service Bulletin must be accomplished by 31.07.2008 at the latest. F. Approval The information or instructions contained in this document refer to change no. 1257. The technical content of this document is approved under the authority of DOA No. EASA.21J.034.

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# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 2 of 9 2008-04-14 G. Manpower Approx. 2 man–hours. H. Weight and Balance Not applicable. I. Electrical Load Data Not applicable. J. Software Accomplishment Summary Not applicable. K. References Not applicable. L. Other Publications affected The changes to AMM MBB BK117 C-2, IPC MBB BK117 C-2 and FLM MBB BK117 C-2 which are required as a result of this Alert Service Bulletin will be incorporated with one of the next revisions. M. Interchangeability of Parts Not applicable.



### 2. Material Information A. Material – Price and Availability Information on cost and availability of required retrofit kit SB-117C2-67A-008-2C will be provided by ECD, Dept. Spares Order Administration on request. B. Support Information Not applicable.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 3 of 9 2008-04-14 C. Material Necessary for Each Helicopter Retrofit kit SB-117C2-67A-008-2C. No. New P/N Keyword Old P/N Qty Disposition

1 L311M1038207 Rubber washer

− 1 A 2 LN91793208E Countersunk rivet

− 1 A 3 LN6504932M Washer

− 1 A 4
− Slide L670M1045208 1 B 5
− Spring L670M1045220 1 B 6
− Washer L670M1045217 2 B 7
− Washer L670M1045214 2 B 8
− Washer L670M1045211 2 B 9
− Blind rivet MBBN3013M3207 1 B 10
− Blind rivet MBBN3013M3206 1 B 11
− Dry cleaning solvent (CM 202) − a.n.* C
12
− Lacquer (CM 4012) − a.n.* C
13
− Hardener (CM 4013) − a.n.* C *a.n. = as needed Disposition: A = New, included in kit. B = Part with old P/N is discarded. Discarded parts are not taken back by ECD. C = Consumable material, to be ordered as required from the Interturbine company. CM item number i.a.w. list of consumable materials in the AMM. D. Material Necessary for Each Spare See Section 2.C. E. Reidentified Parts Not applicable. F. Special Tooling Not applicable.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 4 of 9 2008-04-14 3. Accomplishment Instructions A. Preliminary work: (1) Remove cantilever (7, Figure 1) as follows: (a) Remove rubber band (6, Figure 1) from ring (5) on cantilever (7). (b) Loosen nut (3, Figure 1) on cantilever (7). (c) Remove screw (8, Figure 1) with washers (4) from cantilever (7). B. Modification of cantilever (1, Figure 2): (1) Using drill bit dia. 3.2 mm, drill out blind rivets (3, 4, Figure 2) from cantilever (1). Completely remove rivet remains. (2) Remove slide (5, Figure 2), spring (6) and washers (7, 8, 9) and discard. (3) Rivet pivot plate (2, Figure 2) to cantilever (1) using countersunk rivet (3) and washer (10). (4) Push rubber washer (6) over pin (3) i.a.w. Figure 3. C. Identification of the cantilever (1, Figure 4): (1) Remove all dirt and grease from the surface to be marked in the area of the part number on the inside of the cantilever (1, Figure 4) using dry cleaning solvent (CM 202). Leave the cleaned area to air. (2) Write the number of this Alert Service Bulletin onto the area near the part number on the inside of the cantilever (1, Figure 4) using a waterproof pen. (3) Protect the marking by lacquer (CM 4012, CM 4013). D. Conclusive works: (1) Install cantilever (7, Figure 1) as follows: (a) Position cantilever (7, Figure 1) above bushing (2) in the tube of the cyclic stick (1). (b) Install cantilever (7, Figure 1) with screw (8), washers (4) and nut (3). Tighten nut (3) to such an extent that an axial play of 0.1–0.2 mm remains. (c) Hook rubber band (6, Figure 1) onto ring (5) on cantilever (7). (2) Fold the cantilever (1, Figure 5) towards the cyclic stick (2) and lock it to the cyclic stick by means of the rotary fastener (3). E. Confirm accomplishment of this Alert Service Bulletin by an entry in the historical record of the helicopter. 

### 4. Appendix Not applicable.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 5 of 9 2008-04-14 Removal/Installation Cantilever Figure 1 1 Cyclic stick 2 Bushing 3 Nut 4 Washer 5 Ring 6 Rubber band 7 Cantilever 8 Screw 1

2

3 4 4

5
6 7 8

Shown after modification. Tighten to such an extent that an axial play of 0.1–0.2 mm remains.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 6 of 9 2008-04-14 Modification of Cantilever Figure 2 

### Section 

## B–B Section 

## A–A

1 

## A A Before modification.

After modification.

1 Cantilever 2 Pivot plate 3 Blind rivet MBBN3013M3207 Countersunk rivet LN9179-3208E 4 Blind rivet 5 Slide 6 Spring 7 Washer 8 Washer 9 Washer 10 Washer LN65049-32M Before modification. After modification. B B 1

5

2 4 

### 3

7 8 9 8 7 6

2 1

3

10

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 7 of 9 2008-04-14 Installation of Rubber Washer to Pin Figure 3 Detail A 

## A

1 Cyclic stick 2 Bracket 3 Pin 4 Instrument panel 5 Cantilever 6 Rubber washer L311M1038207 1

2

3

3 4 5 6 6

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 8 of 9 2008-04-14 Identification of Cantilever Figure 4 1 B856M1011101 ASB MBB BK117 C-2-67A-008

1 Cantilever

Identification on the inside of the cantilever. Mark with the number of this Alert Service Bulletin.

# ALERT SERVICE BULLETIN MBB BK117 C-2

MBB BK117 C-2-67A-008 PAGE 9 of 9 2008-04-14 Cantilever Locking Figure 5 1 Cantilever 2 Cyclic stick 3 Rotary fastener 1 2

3