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.

This document is available on the internet: www.eurocopter.com/techpub
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 3 4

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