T.F.S. No. 00000579 

Approved under EASA DOA No. 21J.056 Page 1/21 

2010.04.23

EUROCOPTER 

DIRECTION TECHNIQUE SUPPORT

13725 MARIGNANE CEDEX FRANCE

EMERGENCY

ALERT SERVICE BULLETIN 

ECUREUIL NUMBER VERSIONS 

AS350 05.00.62 Civil: 

Military: 

B-BA-BB-B1-B2-D 

L1 

AS355 05.00.57 Civil: E-F-F1-F2-N 

AS550 05.00.38 Military: A2-C2-U2 

AS555 05.00.35 Military: AF-AN-SN-UF-UN 

SUBJECT: TIME LIMITS / MAINTENANCE CHECKS

Periodic inspection of the Tail Gear Box (TGB) control lever

ATA: 65 

REVISION No. DATE OF APPROVAL DATE OF ISSUE 

 

Revision 0 On: March 30, 2010 2010.03.31 

Revision 1 On: April 22, 2010 2010.04.23 

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

THE INFORMATION AND THE INSTRUCTIONS 

CONTAINED IN THIS ALERT SERVICE BULLETIN 

ARE INTENDED FOR MAINTENANCE PERSONNEL 

AND FOR FLIGHT CREWS.

1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters/installed equipment 

Helicopters equipped with a Tail Gear Box (TGB) fitted with a control lever P/N: 

- 350A33-1058-00, 

- 350A33-1058-01, 

- 350A33-1058-02, 

- 350A33-1058-03, 

and not marked with an "X" in the area shown in Figure 7. 

NOTE 1

The following are not concerned by the instructions given 

in this ALERT SERVICE BULLETIN: 

1) Control levers P/N: 

- 350A33-1524 all dash numbers, 

- 350A33-1526 all dash numbers. 

2) Control levers P/N: 350A33-1058-00/01/02/03 marked 

with an "X" in the area shown in Figure 7. 

1.A.2. Non-installed equipment 

- Tail Gear Boxes (TGBs) fitted with a control lever P/N 350A33-1058-00/01/02/03 and not marked 

with an "X" in the area shown in Figure 7. 

- Control levers P/N 350A33-1058-00/01/02/03 and not marked with an "X" in the area shown in 

Figure 7. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 
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1.C. REASON 

1) To monitor TGB control levers to make sure there are no cracks. 

2) To prevent the risk of cracks occurring in TGB control levers. 

Revision 0 of this ALERT SERVICE BULLETIN did not form the subject of an EASA Airworthiness 

Directive. 

The purpose of Revision 1 of this ALERT SERVICE BULLETIN is to extend the deadline for 

application of the rework procedure described in paragraph 2.B.3. to 660 hours, without exceeding 

June 30, 2011. 

Revision 1 of this ALERT SERVICE BULLETIN will form the subject of an EASA Airworthiness 

Directive. 

1.D. DESCRIPTION 

Revision 0: 

An accident occurred involving an AS350 B2 helicopter; the cause of the accident was the failure of 

control lever P/N 350A33-1058-03. 

Initial investigations on site showed that the area of failure of the control lever was similar to that in 

cases encountered previously where it was demonstrated that the crack was due to non-compliant 

installation. 

Therefore EUROCOPTER issued Safety Information Notice (SIN) No. 2106-S-65 on October 29, 

2009, to remind operators of the installation procedure and of the checking instructions which are 

applicable following installation of the control lever. 

Concerning the latest case, further investigations have not formally concluded non-compliant 

installation of the TGB control lever; only a few surface anomalies were revealed. 

In order to remove any surface anomalies which could lead to reduced strength, EUROCOPTER has 

defined mandatory local reworking of the area concerned. 

Pending this rework, a visual inspection of the area is required during the ALF check in order to detect 

any cracks. 

An analysis of this incident has determined that only the control levers with the part numbers specified 

in paragraph 1.A.1. are concerned by the instructions given in this ALERT SERVICE BULLETIN. 

Revision 1: 

Following the issue of Revision 0, many operators preferred ordering new, reworked or reinforced 

levers, although there was no technical difficulty in carrying out the rework operation defined in 

paragraph 2.B.3. 

In view of this unexpected increase in the number of orders, and considering that the ALF check 

guarantees the safety of the daily flights, EUROCOPTER has extended the time limit for retrofitting the 

fleet, in accordance with the instructions of paragraph 1.E.2. 
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1.E. COMPLIANCE 

EUROCOPTER renders compliance with this ALERT SERVICE BULLETIN mandatory. 

1.E.1. Compliance at the works 

1.E.1.a. On helicopters: 

 Comply with paragraph 2.B.3. before delivery of helicopters. 

1.E.1.b. On non-installed equipment 

 Comply with paragraph 2.B.3. before delivery to customers. 

1.E.2. Compliance in service 

1.E.2.a. On helicopters/installed equipment 

1) Comply with paragraph 2.B.1. during the next check after the last flight of the day, without 

exceeding 10 flying hours, following receipt of this ALERT SERVICE BULLETIN issued on the 

date indicated at the foot of the page 

 Then, 

 Comply with paragraph 2.B.1. during each check after the last flight of the day, without 

exceeding 10 flying hours, until compliance is ensured with paragraph 2.B.3. which describes 

the rework procedure necessary to raise compliance with the instructions given in this ALERT 

SERVICE BULLETIN. 

2) Comply with paragraph 2.B.3. within 660 flying hours following receipt of Revision 0 of this 

ALERT SERVICE BULLETIN, issued on March 31, 2010, and at the latest by June 30, 2011. 

1.E.2.b. On non-installed equipment 

Comply with paragraph 2.B.3. before installation on a helicopter and at the latest before June 30, 

2011. 

1.F. APPROVAL 

1.F.1. Approval of modifications 

Not applicable. 

1.F.2. Approval of the Service Bulletin 

The technical information contained in this ALERT SERVICE BULLETIN Révision 0 was approved 

on March 30, 2010 under the authority of EASA Design Organisation Approval No. 21J.056 for civil 

version helicopters subject to an Airworthiness Certificate. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 0 was approved 

on March 30, 2010 by the EUROCOPTER Airworthiness Department for military version helicopters. 
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2010.04.23

The technical information contained in this ALERT SERVICE BULLETIN Revision 1 was approved 

on April 22, 2010 under the authority of EASA Design Organisation Approval No. 21 J.056 for civil 

version helicopters subject to an Airworthiness Certificate. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 1 was approved 

on April 22, 2010 by the EUROCOPTER Airworthiness Department for military version helicopters. 

1.G. MANPOWER 

1.G.1. Qualification 

1 Mechanical Engineering Technician, 

Or 

1 suitably trained pilot, qualified in accordance with the local regulation (only for the visual check 

specified in paragraph 2.B.1.). 

1.G.2. Time for the operations 

Approximately 5 minutes for the visual check. 

Approximately 3 hours to replace the control lever. 

Approximately 5 hours to locally rework the control lever (including control lever removal / installation 

time). 

1.G.3. Estimated helicopter grounding time 

Less than 1 day. 

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 

Maintenance Manual (MET) Work Card: 

- 65.20.00.401. 

Standard Practices Manual (MTC) Work Cards: 

- 20.02.05.404. 

- 20.02.09.101. 

- 20.02.09.601. 

- 20.04.02.401. 

- 20.04.04.401. 

- 20.04.04.403. 

- 20.04.05.402. 

- 20.04.05.410. 

- 20.08.05.103. 

1.L. OTHER DOCUMENTS AFFECTED 

Maintenance Program (PRE) section 05.98 or 05.99 will be modified in accordance with this ALERT 

SERVICE BULLETIN. 

1.M. TOOLING AFFECTED 

 Not applicable. 

1.N. INTERCHANGEABILITY OR MIXABILITY OF PARTS 

 Not applicable. 
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2. ACCOMPLISHMENT INSTRUCTIONS 

2.A. GENERAL 

NOTE 1

Eurocopter remains at your disposal for any additional 

information or support you may require in order to comply 

with the instructions given in this ALERT SERVICE 

BULLETIN; contact the EUROCOPTER Customer 

Service Technical Support Department by: 

Tel.: +33 (0)4.42.85.99.67 

Fax: +33 (0)4.42.85.99.66 

Email: DynComp.Technical-Support@eurocopter.com

2.B. OPERATIONAL PROCEDURE 

2.B.1. Procedure 

2.B.1.a. Visual check of the control lever 

Using a mirror, visually inspect control lever (a) in inspection area (A) shown in Figures 1 and 2, 

and make sure that there are no cracks. 

2.B.1.b. Interpretation of the results 

1) If there are no cracks: 

- Leave as is. 

- Resume flights. 

2) If there is a crack: 

- Contact the EUROCOPTER Customer Service Technical Support Department as per the 

instructions in NOTE 1 in paragraph 2.A. 

- Replace affected control lever (a) with a new control lever (7) as per procedure 2.B.2. and 

paragraph 3.C. 

- Resume flights. 
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2.B.2. Removal / Installation of the control lever (Figure 3) 

a) Removal of control lever (a)

- Open the TGB fairing, 

- Remove cotter pin (e) and remove nut (f), threaded pin (k) and washer (h), 

- Discard cotter pin (e), nut (f) and washer (h), 

- Remove cotter pin (g) and remove nut (j), screw (c) and washers (d), 

- Discard cotter pin (g), nut (j) and washers (d), 

- Remove expansible bolt (q) with spacer (p), cotter pin (n) and nut (m) as per MET Work Card 

65.20.00.401. 

CAUTION 

WHEN YOU REMOVE THE EXPANSIBLE BOLT, YOU 

MUST COMPLY WITH THE INSTRUCTIONS GIVEN ON 

MET WORK CARD 65.20.00.401. 

- Discard cotter pin (n) and nut (m). 

- Remove control lever (a). 

b) Installation of control lever (7)

- Offer up control lever (7) on the TGB. 

- Install expansible bolt (q) with spacer (p), cotter pin (2) and nut (1) as per MET Work Card 

65.20.00.401. 

CAUTION 

WHEN YOU INSTALL THE EXPANSIBLE BOLT, YOU 

MUST COMPLY WITH THE INSTRUCTIONS GIVEN ON 

MET WORK CARD 65.20.00.401. 

- Install screw (c) and washers (6), then torque tighten nut (1) and safety with cotter pin (2). 

- Install threaded pin (k) and washer (3), then torque tighten nut (4) as per MTC Work Card 

20.02.05.404 and safety with cotter pin (5). 

- Close the TGB fairing. 
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2.B.3. Rework procedure for area B of the control lever (Figures 4, 5 and 6) 

NOTE 2

Only the rib shown in Figure 4 (Area B) is to be reworked. 

- Remove the control lever as per paragraph 2.B.2.a. 

For control levers which have logged flying hours: 

- Before reworking area B of the control lever, check that there are no cracks by performing a local 

non-destructive inspection of the control lever in inspection area A (See Figures 1 and 2): 

. Strip the inspection area of control lever (a) as per MTC Work Card 20.04.02.401. 

. Perform local non-destructive inspection of the inspection area (for example, dye penetrant 

inspection as per MTC Work Cards 20.02.09.101 and 20.02.09.601). 

- Interpret the results as per paragraph 2.B.3.a. 

For control levers which have never been installed on a helicopter: 

- Rework the control lever as per the procedure described below in paragraph 2.B.3.b. 

2.B.3.a. Interpretation of the results

1) If there are no cracks: 

- Rework the control lever as per paragraph 2.B.3.b. 

2) If there is a crack: 

- Contact the EUROCOPTER Customer Service Technical Support Department as per the 

instructions in NOTE 1 in paragraph 2.A. 

- Replace the control lever as per paragraph 2.B.2.b. and paragraph 3.C. 

- Resume flights. 

2.B.3.b. Rework of the control lever

- Measure dimension "e" before starting the rework (Figure 4). 

As per Figures 5 and 6: 

- Manually rework area B as per MTC Work Card 20.04.04.401. 

. Sand area B progressively with P120-grit abrasive paper, then semi-finish the whole of the 

reworked area with P400-grit abrasive paper, taking care to remove all surface scores and 

imperfections and while complying with the following conditions: 

.. Remove a thickness of 0.3 to 0.4 mm. 

.. Comply with a minimum dimension "e" of 14 mm. 

.. There must be a minimum blending radius "R" of 3 mm between the rib and the base of the 

yoke. Use a 6 mm or 7 mm-diameter drill shank wrapped in abrasive paper to produce the 

radius. 
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.. Comply with dimension "C" of 2 mm maximum. 

.. Round off sharp edges on both sides of the reworked area. 

.. In the top part of the rework area, move up progressively in order to blend with the nonreworked part of the rib. 

. Polish the whole of the reworked area in area B with Scotch Brite in order to obtain the highest 

quality finish. 

- Measure dimension "e" after rework. 

. This dimension must be equal to dimension "e" measured before rework less 0.3 to 0.4 mm 

without being less than 14 mm. 

- Measure dimension "C" after rework. 

. This dimension must not be greater than 2 mm. 

- If dimension "e" or dimension "C" are out of tolerance: 

. Contact the EUROCOPTER Customer Service Technical Support Department in accordance 

with the procedures described in NOTE 1 of paragraph 2.A. 

- If dimension "e" and dimension "C" are within the tolerances: 

- Protect area B with Alodine (8) as per MTC Work Card 20.04.04.403. 

CAUTION 

DO NOT PROTECT THE REWORKED AREA WITH 

CHROME ANODIZING. 

- Apply one coat of protective P05 primer paint (9) over area B as per MTC Work Card 

20.04.05.402. 

- Apply a second coat of protective P05 primer paint (9) over area B as per MTC Work Card 

20.04.05.402, allowing the drying time between the two coats. 

- Apply top coat paint (10) as per MTC Work Card 20.04.05.410. 

- Using indelible ink, mark an "X" on the control lever as per paragraph 2.D.2. 

- Install the control lever as per paragraph 2.B.2.b. 

- Resume flights. 

2.C. OPERATIONAL PROCEDURE ON NON-INSTALLED EQUIPMENT 

Identical to paragraph 2.B.3. 

2.D. IDENTIFICATION 

2.D.1. Identification of modifications in the documentation 

a) Record first compliance with this ALERT SERVICE BULLETIN on the equipment log card (FM) of 

the TGB. 

b) Record compliance with paragraph 2.B.3. of this ALERT SERVICE BULLETIN on the equipment 

log card (FM) of the TGB.
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2.D.2. Identification of modifications on equipment 

Mark an "X" on the control lever near to the control lever part number, as per MTC Work Card 

20.08.05.103 and as per Figure 7: 

. use indelible ink and, 

. apply VERNELEC 43022 protective varnish. 

2.E. OPERATING AND MAINTENANCE INSTRUCTIONS 

Not applicable. 
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2010.04.23

 

Figure 1: 

Visual inspection of the control lever

a 

A 

a 

A 

A 

Ref.: TGB shaft 

Ref.: Mirror

Ref.: TGB fairing 

Ref.: Pitch-change unit 

Ref.: TGB casing yokes 
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Figure 2: 

Area of the control lever to be inspected

A 

A

a 

A
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Figure 3: 

Removal / Installation of the control lever 

a - 7 

c

d - 6 e - 5 

f - 4 

g - 2 

h - 3 

j - 1 

m - 1 

p

q

n - 2 

k
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Figure 4: 

Reworking of the control lever 

B

Dimension "e" 

B 
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Figure 5: 

Reworking of the control lever 

Before reworking

After reworking

Minimum radius = 3 mm 

0.3 to 0.4 mm 

2 mm maximum 

14 mm minimum

Round off sharp edges on 

both sides of the reworked 

area 

Move up progressively in order 

to blend with the non-reworked 

part of the rib 
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Figure 6: 

Reworking of the control lever 

Dimension « C » = 2 mm 
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Figure 7: 

Marking 

Marking area 
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3. MATERIAL INFORMATION

3.A. MATERIAL: PRICE AND AVAILABILITY 

3.A.1. Cost 

For all information concerning the price of kits and/or components for the modifications, of tools or 

assistance, contact the Eurocopter Customer Service Sales Department or Network. 

3.A.2. Availability 

The kits or components or tools will be delivered on the customer's order. 

3.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT 

Not applicable. 

3.C. MATERIAL REQUIRED FOR EACH HELICOPTER / ENGINE / COMPONENT 

3.C.1. Kits or components to be ordered for one helicopter or one assembly

Material P/N Qty Item Key Word Instructions 

MP/N SAP P/N 

 

ASNA0044-080BCL 782658 2 1 Nut Replace 

23310CA015020 740026 2 2 Cotter pin Replace 

23111CA060 739933 1 3 Washer Replace 

ASNA0045-060BCL 1154014 1 4 Nut Replace 

23310CA015015 740025 1 5 Cotter pin Replace 

23112CA080 739946 2 6 Washer Replace 

Control lever to be ordered separately

Material P/N Qty Item Key Word Instructions 

MP/N SAP P/N 

 

350A33-1058-03 

Marked with an "X" on the 

control lever 

Or 

350A33105803 1 7 Control lever 

350A33-1526-00 350A33152600 1 7 Reinforced 

control lever 

Or 

350A33-1524-00 350A33152400 1 7 Reinforced 

control lever 

 
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3.C.2. Material to be ordered separately 

Material P/N Qty Item Key Word Instructions 

MP/N SAP P/N 

 

MIL-DTL-81706 AR 8 Alodine 1200 

DHS186-111.20 86741 AR 9 P05 protection 

DHS186-111.21 AR - Hardener 

DHS186-111.22 AR - Thinner 

ECS2022.20-2640 AR 10 Top coat paint 

 

NOTE 1

When ordering P05 primer paint (DHS186-111.20), 

please order hardener (DHS186-111.21) and thinner 

(DHS186-111.22). 

The products necessary for compliance with the Work Cards mentioned in paragraph 1.K. can be 

ordered from the INTERTURBINE company: 

Website: http://www.itlogistics.de

Telephone: +49.41.91.809.300 

AOG: +49.41.91.809.444. 

3.C.3. Material to be modified at the Manufacturer's or to be returned 

Not applicable. 

3.C.4. Products to be ordered separately 

Not applicable. 

3.C.5. Tools 

Not applicable. 

3.C.6. Material supplied by the User 

Not applicable. 
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3.D. 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 2

For ALERT SERVICE BULLETINS, order by: 

Telex: HELICOP 410 969F 

Fax: +33 (0)4 42 85 99 96 

NOTE 3

On the purchase order, please specify the mode of transport, 

the destination and the serial numbers of the helicopters to be 

modified. 

3.E. MATERIAL TO BE RETURNED 

Not applicable. 

4. APPENDIX 

Not applicable