ALERT SERVICE BULLETIN AS350 

Approved under EASA DOA No. 21J.056. 55.00.16 Page 1/15

This document is available on the internet: www.eurocopter.com/techpub 2009.01.05

 EUROCOPTER CIVIL VERSION(S): B,B1,B2,B3,BA,BB,D 

 DIRECTION TECHNIQUE SUPPORT MILITARY VERSION(S): L1 

 13725 MARIGNANE CEDEX FRANCE

ALERT SERVICE BULLETIN 

No. 55.00.16 

SUBJECT: STABILIZER(S) 

Improvement of attachment strength for upper and lower fin skids 

Corresponds to MOD 073330 

REVISION No. DATE OF APPROVAL DATE OF ISSUE 

 

Revision 0 On: February 28, 2008 2008.02.28 

Revision 1 On: December 22, 2008 2009.01.05 

 

 
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1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters / Equipment installed on aircraft 

Helicopters pre-MOD 073330, fitted with fins whose P/N listed in paragraph 1.A.2. 

NOTE 1

Refer to the aircraft Certificate of Conformity (or RIC AMSIndividual Inspection Log Book), the Equipment Log Cards 

(FME) or the aircraft Log Book to identify the actual 

modification status of the aircraft. 

1.A.2. Equipment not installed on aircraft 

- Upper fin assembly P/N: 350A14-0020-00XX. 

- Upper fin assembly P/N: 350A14-0020-01XX. 

- Upper fin assembly P/N: 350A14-0020-02XX. 

- Upper fin assembly P/N: 350A14-0020-03XX. 

- Upper fin assembly P/N: 350A14-0020-08XX. 

- Upper fin assembly P/N: 350A14-0020-09XX. 

- Upper fin assembly P/N: 350A14-0020-10XX. 

- Upper fin assembly P/N: 350A14-0020-17XX. 

- Upper fin assembly P/N: 350A14-0020-18XX. 

- Upper fin assembly P/N: 350A14-0020-19XX. 

- Upper fin assembly P/N: 350A64-1144-00XX. 

- Lower fin assembly P/N: 350A14-0021-00XX. 

- Lower fin assembly P/N: 350A14-0021-01XX. 

- Lower fin assembly P/N: 350A14-0021-02XX. 

- Lower fin assembly P/N: 350A14-0021-03XX. 

- Lower fin assembly P/N: 350A14-0021-04XX. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 
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1.C. REASON 

The purpose of this Alert Service Bulletin is to improve the fatigue strength of the upper and lower fin 

attachment. 

Revision 0 of this Alert Service Bulletin formed the subject of an EASA Airworthiness Directive 

No. 2008-0121. 

Compliance with this Alert Service Bulletin replaces compliance with Revision 1 of Alert Service Bulletin 

No. 55.00.12 for versions B, B1, B2, BA, BB, D and L1. 

Compliance with this Alert Service Bulletin cancels compliance with the instructions of Revision 1 of Alert 

Service Bulletin No. 55.00.13 for version B3. 

This information will be made official by Revision 2 of Alert Service Bulletin No. 55.00.13. 

The purpose of this Alert Service Bulletin Revision 1 is to supplement the list of upper and lower fin P/Ns for 

which this Alert Service Bulletin is applicable. 

Revision 1 of this Alert Service Bulletin does not supersede compliance with Revision 0 and will form the 

subject of an EASA Airworthiness Directive. 

1.D. DESCRIPTION 

During take-off of an aircraft from Ecureuil family, the upper fin tilted leftwards. 

This technical event formed the subject of Alert Service Bulletin No. 55.00.12 and No. 55.00.13. 

This Alert Service Bulletin defines the modifications to be embodied in order to correct the initially 

encountered anomalies. 

In order to introduce a corrective solution, EUROCOPTER studied modification 073330 which consists of: 

- reducing risks of loaded installation by increasing the diameter of passage holes for 

 bolts on lower and upper fin attachment fittings on tail boom. 

- improving fatigue strength of upper and lower fin attachment by replacing 

 bolts P/N: 22126BV060032L with special bolts with higher head P/N: 350A23-4016-20 and replacing 

 washers P/N: 23112AG060LE with special washers P/N: 350A23-4017-22. 

For these reasons, EUROCOPTER renders compliance with this Alert Service Bulletin mandatory. 
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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 helicopter 

 Not applicable. 

NOTE 2

Modification 073330 is introduced in design definition of new 

helicopters delivered as from 1st April 2007. 

NOTE 3

This date is for information, refer to the aircraft Certificate of 

Conformity (or RIC AMS- Individual Inspection Log Book), 

the Equipment Log Cards (FME) or the aircraft Log Book to 

identify the actual modification status of the aircraft. 

1.E.1.b. On equipment not installed on aircraft 

 Before delivery, comply with paragraph 2.C. 

1.E.2. Compliance in operation 

1.E.2.a. On helicopter / equipment installed on aircraft: by operator 

Comply with paragraphs 2.A. and 2.B. of this Alert Service Bulletin, publish at the date mentioned in the 

page footer, by March 31, 2009 at the latest. 

1.E.2.b. On equipment not installed on aircraft 

 Before installation on helicopter modify stocks as per paragraph 2.C. by March 31, 2009, at the latest. 

1.F. APPROVAL 

Approval is limited to civil version helicopters subject to an Airworthiness Certificate. 

1.F.1. Approval of modifications 

The information or instructions relating to modification 073330, Issue 2, were approved on April 25, 2007. 
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1.F.2. Approval of Alert Service Bulletin 

The technical information contained in this Alert Service Bulletin No. 55.00.16 Revision 0 was approved on 

February 28, 2008 under the authority of EASA Design Organization Approval No. 21J.056. 

The technical information contained in this Alert Service Bulletin No. 55.00.16 Revision 1 was approved on 

December 22, 2008 under the authority of EASA Design Organization Approval No. 21J.056. 

1.G. MANPOWER 

1.G.1. Qualification 

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

qualifications: 

Qualification: 1 Mechanical Technician. 

1.G.2. Time 

Time values are indicated for reference, for a standard configuration. 

Time: 4 hours approximately for Mechanical Technician. 

1.G.3. Estimation of aircraft downtime 

1 day approximately. 

1.H. WEIGHT AND BALANCE 

1.H.1. Weight 

Weight negligible. 

1.H.2. Moment 

Moment negligible. 

1.I. EFFECT ON ELECTRICAL LOADS 

Aircraft's electrical load analysis is not affected. 

1.J. SOFTWARE MODIFICATION EMBODIMENT STATE 

Not applicable. 
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1.K. REFERENCES 

The following documents are required for compliance with this Alert Service Bulletin: 

MET: 24.00.00.301: Electrical generation - General instructions, 

MET: 55.00.00.402: Stabilizer: Removal - Installation, 

MET: 65.20.00.401: Tail gearbox (B.T.A.), hub body and spider plate - 

Removal - Installation, 

MTC: 20.02.06.402: Safetying and locking of assemblies – Safetying with lockwire, 

MTC: 20.04.03.102: Corrosion inhibiting and removal procedures – Surface protective treatment against 

corrosion, 

MTC: 20.04.05.101: Paint and primer application procedure – General information concerning painting 

means and paint touch-ups, 

MTC: 20.05.01.211: Sealing compounds used in structural repairs or on transmission assemblies - Sealing 

compound MASTINOX 6856, 

MTC: 20.05.01.222: Sealing compounds used in structural repairs or on transmission assemblies - Sealing 

compound PR 1771 B2, 

MTC: 20.06.02.303: Bonding with araldite compounds - ARALDITE AW 106, 

MTC: 20.07.03.408: Technical instructions – General principles applicable for visual cleanliness, appearance 

checks on an aircraft after an inspection or repair. 

MTC: 20.08.05.103: Monitoring of parts in operation, marking and service life customization 

1.L. OTHER DOCUMENTS CONCERNED 

This Alert Service Bulletin will give rise to amendment of the following documents by EUROCOPTER: 

Illustrated Parts Catalog (IPC). 

This document will be circulated at a later date. 

1.M. TOOLING AFFECTED 

Not applicable. 

1.N. INTERCHANGEABILITY AND MIXABILITY BETWEEN THE PARTS 

1.N.1. Interchangeability 

Fins pre- and post-MOD are physically but not functionally interchangeable. 

1.N.2. Mixability 

Mixability of parts is prohibited. 
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2. ACCOMPLISHMENT INSTRUCTIONS 

2.A. GENERAL 

- Before any intervention refer to general instructions on electrical generation as per Work Card 

24.00.00.301 (MET). 

- Safetying with lockwire as per Work Card 20.02.06.402 (MTC). 

- Protection against corrosion as per Work Card 20.04.03.102 (MTC). 

- Refer to guidelines on painting means and paint touch-ups as per Work Card 20.04.05.101 (MTC). 

- Sealing with Mastinox as per Work Card 20.05.01.211 (MTC). 

- Sealing with sealing compound as per Work Card 20.05.01.222 (MTC). 

- Bonding with adhesive as per Work Card 20.06.02.303 (MTC). 

2.B. OPERATIONAL PROCEDURE 

2.B.1. Preliminary steps 

Implement suitable access means. 

2.B.2. Procedure 

2.B.2.a. Removal of fins (Figure 1) 

- Remove and separate upper fin (e) from lower fin (f) as per Work Card 55.00.00.402 (MET). 

- Scrap bolts (c) and washers (b). 

2.B.2.b.Modification of lower and upper fittings on work bench (Figure1, Detail A and Section D-D) 

NOTE

Modification procedures for lower and upper fittings (a) are 

identical. Carry out the following procedure for each fitting 

(a). 

- Increase initial diameter of passage holes for bolts in fitting (a) from 7 mm to 7.5 mm + or – 0.1 mm. 

- Deburr and carry out protection against corrosion. 

- Carry out paint touch up, as required, as per Work Card 20.04.05.101 (MTC). 

2.B.2.c.Installation of fins (Figure 1, Detail A and Section B-B) 

- Assemble upper fin (e) and lower fin (f) as per Work Card 55.00.00.402 (MET). 

- Offer up fin assembly on tail boom. 

- Check presence of peel washers (d) installed underneath fitting (a): 

• If peel washers are present (d), check that fitting (a) is properly resting on existing washers (d). 

Otherwise, remove peel washers (d) and carry out procedure below, 
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• if no peel washers are present (d) check clearance between fin and skin of tail boom as per Work Card 

55.00.00.402 (MET) and should setting be required: 

o define thickness of peel washers (4) to be installed as per clearance read, 

o install and bond peel washers (4) on skin of tail boom by means of adhesive 

(9) and hardener (10) as per Work Card 20.06.02.303 (MTC). 

- Loosen TGB attachment bolts TGB in order to facilitate installation of new bolts (2). 

- Coat shank of bolts (2) with sealant (8). 

- Fit bolts (2) fitted with washer (1). 

- Tighten bolts (2) to torque. 

- Safety bolts (2) by means of lockwire (5). 

- Protect twist of lockwire (5) with a piece of sheath (6). 

- apply bead of sealant (7) on periphery of fitting (a) of fin (e or f) and around heads of bolts (2). 

- Tighten TGB attachment bolts as per Work Card 65.20.00.401(MET). 

- Identifying as per paragraph 2.D. 

- Carry out final steps defined in Work Card 55.00.00.402 (MET). 

2.B.3. Tests 

Not applicable. 

2.B.4. Final steps 

- Restore aircraft to flight condition. 

- Disengage access means. 

- Check aircraft aspect as per Work Card 20.07.03.408 (MTC). 

2.B.5. Ground run-up / Flight test 

Not applicable. 

2.C. OPERATIONAL PROCEDURE ON EQUIPMENT NOT INSTALLED ON AIRCRAFT 

2.C.1. Retrofitting of spare part stocks 

Retrofit stock of fins mentioned in paragraph 1.A.2. as per paragraph 2.B.2.b. and identify as per 

paragraph 2.D. 

2.C.2. Replacement, scrapping and stock building-ups 

Not applicable. 
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2.D. IDENTIFICATION 

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

- Record embodiment of modification 073330 and compliance with this Alert Service Bulletin No. 55.00.16 

 revision 1 in the aircraft documents. 

2.D.2. Identification of modifications on material 

Indicate with ink the new part number as per table in zones A, B and C of labels (3). 

Record compliance with this Alert Service Bulletin No. 55.00.16 revision 1 on label (3) in zone D. 

Bond these labels close to that of initial marking. 

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

Upper fin 350A14-0020-00XX 350A08-5506-1301 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-01XX 350A08-5506-0801 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-02XX 350A08-5506-0901 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-03XX 350A08-5506-1001 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-08XX 350A08-5506-1101 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-09XX 355A08-5508-0701 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-10XX 350A08-5506-0201 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-17XX 350A08-5506-1901 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-1801 350A08-5506-0301 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-1802 350A08-5506-0302 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A14-0020-19XX 350A08-5506-1201 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Upper fin 350A64-1144-00XX 355A08-5508-0901 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Lower fin 350A14-0021-00XX 350A08-5506-1401 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Lower fin 350A14-0021-01XX 350A08-5506-1501 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Lower fin 350A14-0021-02XX 350A08-5506-1601 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Lower fin 350A14-0021-03XX 355A08-5508-0801 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 

Lower fin 350A14-0021-04XX 350A08-5506-0401 073330 Ink as per MTC 

20.08.05.103 §4.2.2. 
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2.E. OPERATING AND MAINTENANCE INSTRUCTIONS 

2.E.1. Operating instruction(s) 

Not applicable. 

2.E.2. Maintenance instruction(s) 

Not applicable. 
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Figure 1 
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PAGE LEFT BLANK INTENTIONALLY 
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3. MATERIAL INFORMATION 

3.A. MATERIAL: COST – AVAILABILITY 

3.A.1. Cost 

3.A.1.a.Components 

The components 1, 2, 3, 4 and 6 will be delivered free of charge on operator's order until March 31, 2009. 

3.A.1.b.Tooling 

Not applicable. 

3.A.2. Availability 

3.A.2.a.Components 

The components will be delivered upon operator's order. 

3.A.2.b.Tooling 

Not applicable. 

3.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT 

Not applicable. 

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

3.C.1. Component(s) to be ordered for one helicopter 

Material P/N Qty It. Key Word Former P/N Instruction 

350A23-4017-22 4 1 Washer 23112AG060LE scrap 

350A23-4016-20 4 2 Bolt 22126BV060032L scrap 

ECS2033-32 2 3 Nameplate 
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3.C.2. Material to be ordered separately 

Material P/N Qty It. Key Word Former P/N Instruction 

350A14-0030-20 A/R 4 Washer, peel 

EN3628-0,8 A/R 5 Lockwire 

GAINE2.5X3.5 A/R 6 Sheath 

3.C.3. Material to be modified on the Supplier's premises or to be returned 

Not applicable. 

3.C.4. Material to be ordered separately 

As per Work Cards mentioned in this Alert Service Bulletin and list below. 

The ingredients below can be delivered separately, from INTERTURBINE: 

Website: http://www.itlogistics.de

Telephone: +49.41.91.809.300 

AOG: +49.41.91.809.444 

Material P/N Qty It. Key Word 

 

PR1771B2SEMK654 0.1 kg 7 Sealant 

MASTINOX 6856 K 160 ml 8 Mastinox tube, 160ML 

DHS172-171.20 1 kg 9 Resin, Araldite, 1 kg box (AW106) to be delivered with: 

HV953U 0.8 kg 10 Hardener, 0.8 kg box (see 20.06.02.303 (MTC) 

3.C.5. Tooling 

As per Work Cards mentioned in this Alert Service Bulletin. 

3.C.6. Material provided by the operator 

Not applicable. 

3.C.7. Material required for item not installed on aircraft 

As per paragraphs 3.C.1, 3.C.2 and 3.C.4. 
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3.D. PROCUREMENT CONDITIONS 

Order the required quantity from the EUROCOPTER network's Customer Support Sales Department 

or 

EUROCOPTER 

Etablissement de Marignane 

Direction VENTES Service Client (C.R.) 

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. 

NOTE 2

For ALERT SERVICE BULLETINS, order by: 

Telex: HELICOP 410 969F 

Fax: +33 (0)4.42.85.99.96. 

4. APPENDIX 

Not applicable.