SB No. AS350-64.00.11 

Revision 0 2012-12-19 Page 1/29 

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 Civil Version(s): B3 

 

SERVICE BULLETIN 

SUBJECT: TAIL ROTOR - Tail rotor blades

 Modification of the chin weight support to avoid any interference with the laminated halfbearings 

 Corresponds to modification 076604 

 

Revision No. Date of issue 

Revision 0 2012-12-19 

Summary: 

The purpose of this Service Bulletin is to modify the tail rotor chin weight supports to avoid any interference with the 

laminated half-bearings. 

Compliance: 

EUROCOPTER recommends compliance with instructions contained in this Service Bulletin by detachment of 

EUROCOPTER-approved specialists. 

For the attention of 
 

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1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters/installed equipment

Helicopters equipped with Arriel 2D engines, post MOD 075601 and equipped with the tail rotor blade 

assembly (M/PN) 355A12-0055-00 and pre MOD 076604. 

NOTE 1 

Modification 075601 consists of adding additional chin 

weights, reinforcing the control spider and deleting the load 

compensator lever on the yaw channel, installing the pitch 

lever and the elastomer pitch rod. 

NOTE 2 

Refer to the aircraft Certificate of Conformity (or RIC AMSIndividual Inspection Log Book) to identify the actual 

modification status of the aircraft. 

1.A.2. Non-installed equipment

Tail rotor blade assembly (M/PN) 355A12-0055-00. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. REASON

An interference between the elastomer of the laminated half-bearings fitted on the tail rotor blades and the 

chin weight support was found in operation. This interference occurs under certain in-flight loads. 

This is why EUROCOPTER developed modification 076604 which consists in increasing the chamfer size of 

the chin weight support to avoid the contacts noticed on the laminated half-bearings. 

This Service Bulletin does not supersede the instructions provided in ALERT SERVICE BULLETIN 

No. 01.00.65. 
 

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1.D. DESCRIPTION

Modification 076604 consists in increasing the chamfer size on the chin weight support. 

 pre MOD 076604 post MOD 076604 

Chamfer of 2 mm x 30° 

120° on the upper 

and lower surfaces 

Chamfer of 5 mm x 30°
 

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1.E. COMPLIANCE 

1.E.1. Compliance at the works

Helicopters/installed equipment: 

Not applicable. 

Non-installed equipment: 

Not applicable. 

1.E.2. Compliance in service

Compliance with instructions contained in this Service Bulletin shall be performed by seconding 

EUROCOPTER-approved specialists. 

Helicopters/installed equipment: 

Comply with Paragraph 3 of this Service Bulletin as per the schedule to be defined in accordance with 

EUROCOPTER Technical Support. 

 Non-installed equipment: 

At the operator's initiative, modify stock as per Paragraph 3.B.2. of this Service Bulletin by equipment return 

to EUROCOPTER or to an approved center. 

1.F. APPROVAL

 Approval of modifications: 

The information or instructions relate to modification 076604 which was approved on October 2012, 26 under 

the authority of EASA Design Organization Approval No. 21J.056 for civil version helicopters subject to an 

Airworthiness Certificate. 

 Approval of this document: 

The technical information contained in this Service Bulletin Revision 0 was approved on December 2012, 04 

under the authority of EASA Design Organization Approval No. 21J.056 for civil version helicopters subject to 

an Airworthiness Certificate. 
 

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1.G. MANPOWER

For compliance with this Service Bulletin, EUROCOPTER recommends the following personnel 

qualifications: 

Qualification: 1 EUROCOPTER-approved Specialist Technician.

 Time for the operations is indicated for reference, for a standard configuration. 

Time: 8 hours approximately for the removal/installation of the tail rotor blades and the intervention of the

EUROCOPTER-approved Specialist Technician. 

 Estimated helicopter grounding time: 1 day approximately. 

1.H. WEIGHT AND BALANCE

Not applicable. 

1.I. EFFECT ON ELECTRICAL LOADS

Not applicable. 

1.J. SOFTWARE MODIFICATION EMBODIMENT RECORD

Not applicable. 
 

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1.K. REFERENCES 

The documents required for compliance with this Service Bulletin are as follows: 

Standard Practices Manual (MTC): 

- MTC: 20.04.01.102: Cleaning of parts - Use of cleaning products on individual parts and on aircraft.

- MTC: 20.04.04.403: Cleaning of parts - Touch-up of protective treatment with Alodine 1200.

- MTC: 20.04.05.402: Cleaning of parts - Use of EPOXY primer P05-P20 and P50.

- MTC: 20.08.05.102: Rules in force applicable for repair and maintenance of aircraft.

- MTC: 20.08.05.103: General rules applicable to aircraft: Monitoring of parts in operation - marking – service

life customization.

- MTC : 20.60.00.433: Blades Standard Practices - Preparation of primers and paints. 

Aircraft Maintenance Manual (AMM): 

- AMM: 60-00-00, 3-1: General on mechanics - General instructions - Mechanics. 

- AMM: 60-00-00, 3-2: General on mechanics - General instructions applicable to critical parts. 

- AMM: 64-10-00, 8-10: Tail Rotor Blades - Minor paint touch-up. 

- AMM: 64-10-00, 8-13: Tail Rotor Blades - Removal/Installation - Tail rotor mechanics. 

- AMM: 64-10-00, 8-22: Tail Rotor Blades - Removal/Installation – Additional weights to chin weights 

 post MOD 075601. 

- AMM: 64-10-00, 8-23: Tail Rotor Blades - Removal/Installation – Pitch Horn Assembly post MOD 075601. 

1.L. DOCUMENTS AFFECTED 

The modification will be incorporated in the following manual: 

- Illustrated Parts Catalog (IPC). 

- Master Servicing Manual (MSM). 

The impacted documents shall be updated at the time of a further revision. 

1.M. INTERCHANGEABILITY OR MIXABILITY OF PARTS

 Interchangeability: 

Pre and post MOD tail rotor blade assemblies are interchangeable. 

 Mixability: 

Not applicable. 
 

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2. MATERIAL INFORMATION 

2.A. MATERIAL: PRICE - AVAILABILITY - PROCUREMENT

Price 

For all information concerning the kits and/or components, contact the EUROCOPTER Network Sales and 

Customer Relations Department. 

Availability 

The industrial delivery time shall be given by the Sales and Customer Relations Department on the 

operators’ request. 

Procurement conditions 

Order the required quantity (unless otherwise specified) 

from 

EUROCOPTER 

Etablissement de Marignane 

Direction Ventes et Relations Client (ECR) 

13725 MARIGNANE CEDEX 

France 

NOTE 1 

On the purchase order, please specify the mode of 

transport, the destination and the serial numbers of the 

aircraft to be modified. 

2.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT

Works shall be performed by seconding EUROCOPTER-approved specialists. 

Contact the Sales and Customer Relations Department to schedule the intervention. 
 

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2.C. MATERIAL REQUIRED FOR EACH HELICOPTER/COMPONENT 

Material to be ordered separately: 

Key Word Qty New P/N Item Former 

 P/N Instruction 

 

Gauze swab AR Commercial 1 / / 

Scotch-Brite AR Scotch-Brite 2010 2 / / 

Products to be ordered separately: 

As per Work Cards and/or Tasks mentioned in this Service Bulletin and table below: 

Key Word Qty Product P/N CM Item 

 

Alodine 1200 AR ALODINE1200 CM316 3 

Methyl-ethyl-ketone AR MEK-PUR50L CM217 4 

Distilled water AR / / 5 

Material required for non-installed components: 

Not applicable. 
 

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Specific tooling: 

As per Work Cards and/or Tasks mentioned in this Service Bulletin and table below: 

Key Word Qty Tooling P/N or equivalent RepIte

m 

Kit including: 1 355A12005500-35100 

 

90°-angle head standard drilling 

machine 1 aa 

Set of adjustment rings: 

Thickness Identifiable 

item 

7.4 mm 1 

6.9 mm 2 

6.4 mm 3 

5.9 mm 4 

5.4 mm 5 

4.9 mm 6 

4.6 mm 7 

4.4 mm 8 

4.1 mm 9 

1 2-03 bb 

 

Set of 60°-file milling cutter 1 cc 

Inspection and check support 1 2-06 dd 

Threaded bush 1 2-02 ee 

Check gage min. 3-01 1 3-01 ff 

Check gage max. 3-02 1 3-02 gg 

Milling cutter gage 1 3-3 hh 

Attachment bolt 2 jj 

Silicone extraction pin 1 2-07 kk 

Clamping pin 1 ll 

Reversible adjustable support 1 1-01 mm 

Machining guide 1 1-02 nn 

Set of 5 protective covers 1 pp 

Split bush 1 2-04 qq 

Milling cutter support 1 2-01 rr 

Modeling clay AR ss 

Protective plastic cover AR tt 

Rubbers AR uu 

Ferrofluid oil AR vv 

Reinforced adhesive AR ww 

150 mm seal retainer 2 xx 

12 mm wrench 1 yy 

17 mm wrench 1 zz 

Set of BTR wrenches 1 aaa 
 

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Common tooling: 

Key Word Qty Tooling P/N or equivalent RepIte

m 

Vacuum Cleaner 1 Commercial bbb 

Vice 1 ccc 

Thin brush 2 ddd 

2.D. MATERIAL TO BE RETURNED 

Not applicable. 
 

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3. ACCOMPLISHMENT INSTRUCTIONS 

3.A. GENERAL 

- Read and comply with instructions for use of cleaning products on individual parts and on aircraft, as per 

MTC Work Card 20.04.01.102. 

- Read and comply with ALODINE 1200 touch-up protective treatment as per MTC Work Card 20.04.04.403. 

- Read and comply with the use of EPOXY primer P05-P20 as per MTC Work Card 20.04.05.402. 

- Read and comply with rules in force applicable for repair and maintenance of aircraft as per 

MTC Work Card 20.08.05.102. 

- Read and comply with general instructions applicable to critical parts as per AMM Task 60-00-00, 3-2. 

3.B. OPERATIONAL PROCEDURE 

CAUTION 

 

COMPLY WITH GENERAL INSTRUCTIONS AS 

PER AMM TASK 60-00-00, 3-1. 

CAUTION 

 

SECURE THE TAIL GEARBOX BY APPLYING 

THE ROTOR BRAKE, TO INTERVENE ON THE 

TAIL ROTOR. 

3.B.1. Preliminary steps

- Install suitable access means. 

- Remove the tail rotor mechanics as per AMM Task 64-10-00, 8-13. 

- Remove the pitch horn assemblies as per AMM Task 64-10-00, 8-23. 

- If necessary, remove the additional weights as per AMM Task 64-10-00, 8-22. 
 

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3.B.2. Procedure

3.B.2.a.Preparation of tooling 

- Fully engage 60°-file milling cutter (cc) on 90°-angle head standard drilling machine (aa). 

- Clamp 60°-file milling cutter (cc) using wrenches (yy) and (zz). 

- Position split bush (qq) on 90°-angle head standard drilling machine (aa). 

NOTE 1 

The notch must be in line with the trigger. 

zz 

aa 

yy 

cc 

qq 

aa 
 

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- Position milling cutter support guide (rr). 

- Position inspection and check support (dd). 

rr 

dd 
 

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- Tighten 60°-file milling cutter (cc) in the mandrel using wrench (aaa). 

NOTE 2 

The tightening is performed alternately on the 3 screws of 

milling cutter support guide (rr) until locking in order to center 

60°-file milling cutter (cc). 

- Make sure by hand that inspection and check support (dd) still moves. 

- Check positioning of 60°-file milling cutter (cc) using milling cutter gage (hh). 

dd

hh 

cc

aaa

rr 
 

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- Remove inspection and check support (dd). 

3.B.2.b.Installation of the support and rotor

CAUTION 

 

THE SUPPORT MUST BE SECURED TO A 

MINIMUM HEIGHT OF 900 MM (35.43 IN) FROM 

THE GROUND. 

- Position reversible adjustable support (mm) on a vice (ccc) or on a work bench with seal retainers (xx). 

NOTE 3 

Reversible adjustable support (mm) can be installed in both 

directions according to the chin weight support to be 

machined. 

mm 

ccc 

Moving direction 

dd 
 

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- Position rotor (a) on reversible adjustable support (mm). 

- Lightly clamp (without tightening) chin weight support (b) on reversible adjustable support (mm). 

NOTE 4 

Bolt (jj2) includes one screw 10x80, one Rilsan washer and 

a trunnion nut. 

jj2 

mm 

b 
 

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3.B.2.c.Protection of the chin weight support and chin weights

- Protect the file center and attachment holes of half-bearings with reinforced adhesive (ww). 

- Position rear protective cover (pp1). 

- Tilt the file so as it rests on rear protective cover (pp1). 

- Position a front protective cover (pp2) in the chin weight. 

- Fully engage front protective cover (pp2). 

- Position front protective cover (pp2) in the upper chin weight to keep the file tilted. 
 

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uu 

tt 

uu 

b 

- Plug the space between chin weight support (b) and the file edges with modeling clay (ss). 

- Protect upper chin weight support (b) with protective plastic covers (tt) and rubbers (uu). 

- Position reinforced adhesive (ww). 

ss 

ss 

b 

ww

ww 
 

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- Position protective cover (pp3) or (pp4) on the rear part of chin weight support (b). 

- Position reinforced adhesive (ww). 

3.B.2.d.Installation of a machining guide

- If necessary, clean the positioning holes. 

- Position machining guide (nn) on chin weight support (b). 

NOTE 5 

Machining guide (nn) is fitted with 2 locating pins which rest 

on the chin weight support. 

b pp3 

or 

pp4 

ww 

Locating 

pins 
 

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- Position bolt (jj1) (10 x 90) in machining guide (nn) housing. 

- Align machining guide drillings (nn) and chin weight support (b). 

- Fully engage bolt (jj1). 

- Position washer and base nut. 

- Clamp the assembly. 

3.B.2.e.Preparation of machining

- Position threaded bush (ee) without tightening it. 

nn 

jj1 

b 

ee
 

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- Position adjustment ring (bb) corresponding to the run to be carried out. 

- Bring threaded bush (ee) into contact using clamping pin (ll). 

cc 

bb 

ll 

ee
 

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- Make sure that there are no chips on 60°-file milling cutter (cc). 

- Apply Ferrofluid oil (vv) on 60°-file milling cutter (cc) using a thin brush (ddd). 

- General machining principle: 

. machining is always performed clockwise, 

. the first machining run with 7.4 mm adjustment ring (bb) gives the machining reference value, 

. 60°-file milling cutter (cc) must be tangent to the chamfer, removing only the primer without machining 

the actual part (no or few metal chips), 

. if machining of the part occurred, continue machining runs down to 4.4 mm adjustment ring (bb), 

. remove machining guide plate (nn), 

CAUTION 

 

AFTER THE 4.4 mm ADJUSTMENT RING (8th run), 

CARRY OUT A CHECK BEFORE MACHINING WITH 

4.1 mm ADJUSTMENT RING. IF NECESSARY, 

PERFORM 9th RUN. 

. check chamfer depth with min. (ff) and max. (gg) check gages, 

. if min. (ff) and max (gg) check gages indicate that the dimension is not reached, position 4.1 mm 

adjustment ring (bb) and perform final machining run, 

. for final machining run with 4.1 mm adjustment ring (bb), perform a total of 3 runs (1 clockwise and the 

other 2 moving back and forth). 

vv 

cc ddd 
 

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3.B.2.f. Machining

- Tilt 90°-angle head standard drilling machine (aa). 

- Engage 90°-angle head standard drilling machine (aa) at the center of machining guide (nn) groove. 

- Move 90°-angle head standard drilling machine (aa) to the end of the groove without starting the milling. 

- Press the head of 90°-angle head standard drilling machine (aa) against machining guide (nn). 

aa 

nn 

aa 

nn 

Locating 

pin 
 

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- Perform machining run by holding 90°-angle head standard drilling machine (aa) approximately along the 

groove radius axis on machining guide (nn). 

- Stop 90°-angle head standard drilling machine (aa). 

- Disengage 90°-angle head standard drilling machine (aa) by bringing it back to the groove center of 

machining guide (nn). 

- Tilt 90°-angle head standard drilling machine (aa) to remove it. 

aa 

nn 

Clockwise direction 

nn 
 

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- Remove any chips with vacuum cleaner (bbb) between 2 machining runs. 

- Repeat the procedure described from Paragraph 3.B.2.e. Prepare the machining using smaller size rings. 

NOTE 6 

Machining order of rings: 7.4 mm; 6.9 mm; 6.4 mm; 5.9 mm; 

5.4 mm; 4.9 mm; 4.6 mm; 4.4 mm and 4.1 mm. 

NOTE 7 

Ring thickness is etched on rings, refer to the Tool kit table. 

3.B.2.g.Cleaning

- Remove machining guide (nn). 

- Remove chips using vacuum cleaner (bbb). 

- Wipe using dry gauze swabs (1). 

- Remove modeling clay (ss). 

- Using silicone extraction pin (kk), remove protective covers (pp1) and (pp2) from chin weights. 

ss 

ss 

kk pp2 
 

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- Examine chamfer (c) with min. check gage (ff) and max. check gage (gg). 

- Turn down the rotor to offer up the unmachined blade. 

- Perform the same operations to machine the second face of chin weight support (b) as per 

Paragraph 3.B.2.b. 

 For the third and fourth face to be machined, remove and turn the reversible adjustable support. 

- Perform the same operations as those performed for the first face as per Paragraph 3.B.2.b. 

c 

ff 

ou/or 

gg 

b 
 

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3.B.2.h.Preparation before paint touch-up

- If necessary, remove any chips with vacuum cleaner (bbb). 

- Degrease chamfer (c) with methyl-ethyl-ketone (4). 

- Wait for 15 minutes minimum for methyl-ethyl-ketone (4) to evaporate. 

- Lightly sand chamfer (c) surface with distilled water (5) and Scotch-Brite (2). 

- Position a gauze swab (1) on chamfer (c). 

- Moisten gauze swab (1) with Alodine 1200 (3). 

- Wait for 5 minutes. 

- Remove gauze swab (1). 

- Clean chamfer (c) with distilled water (5). 

- Prepare type-3 primer as per MTC Work Card 20.60.00.433. 

CAUTION 

 

DO NOT APPLY PRIMER ON THE HALFBEARING SEATING PLANE. 

CLEAN WITH A GAUZE SWAB (1), IF 

NECESSARY. 

- Apply type-3 primer on chamfer (c) using a thin brush (ddd). 

- Allow to dry as per MTC Work Card 20.60.00.433. 

c 
 

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3.B.3. Final steps

- Position the pitch horn assemblies as per AMM Task 64-10-00, 8-23. 

- If necessary, position the additional weights as per AMM Task 64-10-00, 8-22. 

- Position the tail rotor mechanics as per AMM Task 64-10-00, 8-13. 

- Remove the access equipment. 

3.C. IDENTIFICATION 

Identification of this document: 

Record compliance with this Service Bulletin Revision 0 in the aircraft documents and on the tail rotor Log 

Card. 

Identification of modifications on the documentation: 

Record compliance with modification 076604 in the aircraft documents and on the tail rotor Log Card. 

Identification of modifications on equipment: 

Identifier parts / assemblies as per the tables below and/or as per MTC Work Card 20.08.05.103 and as per 

AMM 64-10-00, 8-10: 

Key Word Former P/N New P/N MOD Marking type 

Tail rotor blade 

assembly 

355A12-0055-00 355A12-0055-02 076604 Ink 

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS

 Operating instructions: 

Not applicable. 

Maintenance instruction(s): 

Refer to the Master Servicing Manual (MSM), Maintenance Tasks are identical to those to be applied on the 

former tail rotor part numbers. 

The MSM will include these Tasks in a further revision and will then become the reference document. 
 

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Figure 1: Tooling 

ff 

gg 

cc 

dd 

hh 

ee 

qq 

jj ll 

aaa 

aa 

cc 

rr 

mm 

nn 

xx 

pp 

uu 

tt 

zz yy 

vv 

bb 

ww 

ss 

jj1 

jj2 

pp1 pp2 

pp3 pp4 

kk