40220 Tarnos - France

Tel. +33 (0)5 59 74 40 00

Fax. (+33) (0)5 59 74 45 15

MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2

ARRIEL 2 No. 292 72 2861

Object: Accessory gearbox front cover.

Detection of wear on the 41- or 42-tooth gear front bearing 

housing.

The technical information contained in this document has been approved under Design 

Organization Approval No. EASA.21J.070.

Date on which this Mandatory SB becomes effective and must systematically be complied with, 

according to the conditions of application.

Applicable from JUNE 2015

If these resources are available any earlier, the Mandatory SB may be applied prior to the effectivity 

date.

Version: A 

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §1 - 1/1

1. GENERAL

1.1. Purpose

WARNING DANGER: FAILURE TO APPLY THIS MANDATORY SERVICE BULLETIN MAY LEAD TO AN UNCOMMANDED INFLIGHT ENGINE SHUT-DOWN WHICH, ON A SINGLE-ENGINE HELICOPTER, MAY LEAD TO AN

EMERGENCY AUTOROTATION LANDING.

Introduce monitoring to detect wear on the accessory gearbox front cover at the housing of the 41- or 42-tooth 

gear front bearing.

1.2. Reason

TURBOMECA has been informed of an uncommanded in-flight shut-down following rupture of the 41-tooth 

gear, which forms part of the bevel gear of the accessory gearbox (module M01). Investigation into this event 

revealed that the wear on the housing of the front bearing of this gear is a major contributing factor to this 

rupture.

Analysis of the engine history demonstrated that the aluminum content revealed by the Spectrometric Oil 

Analysis (SOA) check evolved significantly in the hours preceding the event.

The SOA check described in this mandatory SB therefore enabled a high aluminum content to be detected, the 

origin of which may be the wear on the housing of the 41- or 42-tooth gear front bearing. This SOA check is the

first step to reduce the risk and will be completed or mended in a second step by a check which could be used 

to measure wear on the housing of the 41- or 42-tooth gear front bearing.

1.3. Description

This mandatory SB consists in performing a periodic SOA check to monitor the evolution of the aluminum 

content.

1.4. Approved by

The technical information contained in this document has been approved under Design Organization Approval 

No. EASA.21J.070.

This Mandatory SB is subject to an Airworthiness Directive.

1.5. Conditions of application

The application conditions of this Mandatory SB are defined respectively in:

- Chapter §2 regarding application at the operator’s site or by a qualified Maintenance Center for level 1, 2.

- Chapter §3 regarding application by a qualified Maintenance Center for level 3.

- Chapter §4 regarding application at a TURBOMECA-approved Repair Center.

1.6. Update history

Not applicable. 

END of section §1

"General"

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 1/8

2. APPLICATION AT THE OPERATOR’S SITE OR BY A QUALIFIED MAINTENANCE CENTER 

FOR LEVEL 1, 2

WARNING DANGER: FAILURE TO APPLY THIS MANDATORY SERVICE BULLETIN MAY LEAD TO AN UNCOMMANDED INFLIGHT ENGINE SHUT-DOWN WHICH, ON A SINGLE-ENGINE HELICOPTER, MAY LEAD TO AN

EMERGENCY AUTOROTATION LANDING.

2.1. Actions to be performed

Perform an SOA check as per paragraph 2.3.2.

2.2. Effectivity and compliance times

ENGINE/VARIANT CODE COMPLIANCE CONDITIONS 

FOR ENGINES IN SERVICE

ARRIEL 2B - 2B1 - 2B1A - 2B1B

1-A

1. Identification of the type of cover in compliance with 

§ 2.3.1.1: Application during the next maintenance 

operation that requires the engine cowling to be opened.

2. SOA check for accessory gearboxes which meet the 

conditions of § 2.3.1.2: Application before 50 operating 

hours is reached (counted from receipt of this Mandatory 

SB), or within 50 hours after installation of the module, 

then every 100 operating hours.

ARRIEL 2C - 2C1 - 2C2

ARRIEL 2D

ARRIEL 2E

ARRIEL 2N

ARRIEL 2S1 - 2S2 

Application of this Mandatory SB is considered mandatory as a result of a technical requirement which might 

affect flight safety of engines in service. It may be done as defined by the effectivity code given in the table 

above.

2.3. Conditions of application for engines in service

2.3.1. Logic-based diagram pertaining to the conditions of Mandatory SB application

2.3.1.1. Identification of the type of cover

This type of casing cover is identified by a visual inspection of the engine. Depending on the 

engine variant (and therefore the type of front mount), the casing cover P/N may or may not be 

legible: it is engraved on the lower RH side of the casing cover (viewed from front of engine), 

below the HMU.

If the P/N is not legible, the surface condition will help to discriminate between "machined" 

casing covers and "casted" casing covers - see Figure 1: 

 "Casted" casing covers have a rough/granular surface,

 "Machined" casing covers have a smooth surface.

If in doubt, contact your Field Representative.

2.3.1.2. SOA check

The SOA check is only applicable to module M01 with a TSN/TSO of over 800 hours and 

equipped with a "machined" accessory gearbox casing cover P/N 0292120650.

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 2/8

Concerned by the SOA check

"Machined" casing cover installed on the engine with its smooth visual appearance

Not concerned by the SOA check

"Casted" casing cover installed on the engine with its granular visual appearance

Figure 1: Identification of a "machined" casing cover

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 3/8

2.3.2. Procedure

Machined

Return the CoC (Appendix 2.1.)

Is the TSN/TSO of module M01 over 800 hours?

YES Do a SOA check of oil as per § 2.4.2.1 *

> 1.4 ppm Remove module M01 within 50 flight hours

Record the SOA check as per § 2.4.4.2.

Do again a SOA check of oil as per § 2.4.2.1 within 100 flight hours

Casted Return the CoC (Appendix 2.1). Identify the casted casing cover in the log card (FMFE) as per §2.4.4.1.

Casing cover standard?

Determinate the aluminum content as per § 2.4.2.2

< 0.8 ppm

Do again a SOA check of oil as per § 2.4.2.1 within 50 flight hours (Do not perform draining before the new check) Between 0.8 ppm and 1.4 ppm Return the CoC (Appendix 2.2). End of procedure

NO End of procedure

* : If the engine is already the subject of SOA follow-up and the aluminum content is present in the laboratory 

reports, the criteria of § 2.4.2.2. are applicable to the last recording of module M01 with a TSN/TSO of 

over 800 hours.

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 4/8

2.4. Accomplishment Instructions

2.4.1. Implementation

The spectrometric oil analysis check following application of this Mandatory SB does not necessitate 

removing the engine from the helicopter.

2.4.2. Operating mode

WARNING DANGER: FAILURE TO APPLY THIS MANDATORY SERVICE BULLETIN MAY LEAD TO AN UNCOMMANDED INFLIGHT ENGINE SHUT-DOWN WHICH, ON A SINGLE-ENGINE HELICOPTER, MAY LEAD TO AN

EMERGENCY AUTOROTATION LANDING.

2.4.2.1. Take an oil sample and send it to an analysis laboratory, refer to the relevant ARRIEL 2 

Maintenance Manual, task 71-02-08-280-801-A01.

Note: When sending, specify that the aluminum content should be mentioned in the analysis 

report.

2.4.2.2. If the data is available, calculate the corrected aluminum content as per the formula of task 

71-02-08-280-802-A01, §5.B.1.b., otherwise apply the following criteria to the raw result of 

the SOA check.

2.4.2.3. Action dependent on the result of the SOA check:

 Aluminum content < 0.8 ppm: Repeat the SOA check within 100 hours

 Aluminum content > 1.4 ppm: Replace module M01 within 50 hours

 0.8 ppm ≤ Aluminum content ≤ 1.4 ppm: Repeat the SOA check within 50 hours in one of the 

following laboratories, without performing draining beforehand:

Laboratory Country

Aviation Laboratories UNITED STATES

Corporation d'Entretien Prédictif CANADA

Gough Group NEW ZEALAND

IHI Jet Service Co JAPAN

Intertek West Lab AS NORWAY

ITS Testing Services UNITED KINGDOM

Jet Care UNITED STATES

Naval Maintenance Establishment NETHERLANDS

RUAG SWITZERLAND

SGS Vernolab FRANCE

SPECTRO UNITED KINGDOM

SPECTRO INC UNITED STATES

SPECTRO OIL AG SWITZERLAND

TEKNIKER SPAIN

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 5/8

2.4.3. Reconditioning and checks

Top up the oil level, refer to the relevant ARRIEL 2 Helicopter Manual.

2.4.4. Identification

2.4.4.1. Identification of the casted casing cover

2.4.4.1.1. Record the application of this Mandatory SB in section "E" of the engine log book.

2.4.4.1.2. Record the application of the Mandatory SB in the module M01 log card (FMFE), 

indicating "Casted casing cover".

2.4.4.1.3. Notify TURBOMECA that this Mandatory SB has been applied by returning the fully 

completed compliance certificate (Appendix 2.1)

2.4.4.2. SOA check

2.4.4.2.1. Record the application of this Mandatory SB in section "E" of the engine log book.

2.4.4.2.2. Record the application of this Mandatory SB in the module M01 log card (FMFE), 

indicating the module M01 TSN and the aluminum content in ppm.

2.4.4.2.3. Notify TURBOMECA that this Mandatory SB has been applied by returning the fully 

completed compliance certificate (Appendix 2.1)

2.4.4.2.4. If necessary, inform TURBOMECA of the replacement of module M01 by returning 

the fully completed compliance certificate (Appendix 2.2 of this Mandatory SB).

2.4.5. Routine maintenance

SOA check to be performed every 100 hours after the first check (or 50 hours depending on the 

aluminum content).

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 6/8

2.5. Material information

2.5.1. List of supplies

Not applicable. 

2.5.2. Supply conditions

Order supplies as needed from:

your local TURBOMECA Support Center

or

TURBOMECA

Support and Services Division

Commercial Department

40220 TARNOS - France

Fax no. +33 (0) 5 59 74 45 11.

2.6. Manpower

- Personnel: 1 mechanic

- Time required: 0.5 hours

2.7. Tooling and/or products

Refer to task 71-02-08-280-801-A01 of the relevant ARRIEL 2 Maintenance Manual.

2.8. WEIGHT AND BALANCE

Not applicable.

2.9. Publication references

Document Engine P/N

Maintenance Manual (MM)

ARRIEL 2B X 292 M5 450 2

ARRIEL 2B1 X 292 N5 450 2

ARRIEL 2B1A X 292 P4 450 2

ARRIEL 2C X 292 M1 450 2

ARRIEL 2C1 X 292 N4 450 2

ARRIEL 2C2 X 292 P6 450 2

ARRIEL 2D X 292 R1 450 2

ARRIEL 2E X 292 R2 300 2

ARRIEL 2N X 292 N2 450 2

ARRIEL 2S1 X 292 L0 301 2

ARRIEL 2S2 X 292 P5 451 2

Spare Parts Catalog (SPC)

ARRIEL 2B X 292 M5 700 2

ARRIEL 2B1 X 292 N5 700 2

ARRIEL 2B1A X 292 P4 700 2

ARRIEL 2C X 292 M1 700 2

ARRIEL 2C1 X 292 N4 700 2

ARRIEL 2C2 X 292 N6 700 2

ARRIEL 2D X 292 R1 700 2

ARRIEL 2E X 292 R2 700 2

ARRIEL 2N X 292 N2 700 2

ARRIEL 2S1 X 292 L0 700 2

ARRIEL 2S2 X 292 P5 700 2

Relevant Helicopter Maintenance Manual.

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 7/8

Objet : Attestation d’application du SB Impératif n° 292 72 2861.

Subject: Mandatory SB No. 292 72 2861 compliance certificate.

Important / Important notice : 

Après application des instructions spécifiées dans ce SB Impératif, veuillez compléter la présente 

attestation et la retourner par courrier ou courriel ou fax à :

After application of the instructions specified in this Mandatory SB, please complete this certificate and return it by 

mail or email or fax it to:

TURBOMECA, Equipe Administration Base installée / Fleet Data Administrator Team, BP 25

40220 TARNOS - France

Fax n° / No. +33 (0) 5 59 74 46 95 – Email: fleetdata@turbomeca.fr

Information concernant le matériel / Equipment information

Utilisateur

Customer

N° Appareil

Aircraft S/N

N/S - S/N Ref. - P/N TSN* TSO* CSN* CSO*

Moteur

Engine

Module M01 

inspecté

Inspected 

module M01

* TSN = Time Since New (Heures depuis neuf) TSO = Time Since Overhaul (Heures depuis RG)

CSN = Cycles Since New (Cycles depuis neuf) CSO = Cycles Since Overhaul (Cycles depuis RG)

Couvercle usiné

Machined casing OUI / Yes NON / NO

PN Couvercle usiné

Machined casing P/N

P/N: __________________________

Je certifie que le moteur identifié ci-dessus a été contrôlé selon les directives de ce SB Impératif.

I certify that the above-mentioned engine has been checked according to the directives given in this Mandatory 

SB.

Date [JJ/MMMM (en lettre)/AAAA 

ou/or DD/MMMM (letters)/YYYY] Nom / Name Fonction / Job title

ANNEXE 2.1 / APPENDIX 2.1

Signature:

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §2 - 8/8

Objet : Attestation de remplacement du module M01.

Subject: Compliance certificate for replacement of module M01.

Important / Important notice : 

Après application des instructions spécifiées dans ce SB Impératif, veuillez compléter la présente 

attestation et la retourner par courrier ou courriel ou fax à :

After application of the instructions specified in this Mandatory SB, please complete this certificate and return it by 

mail or email or fax it to:

TURBOMECA, Equipe Administration Base installée / Fleet Data Administrator Team, BP 25

40220 TARNOS - France

Fax n° / No. +33 (0) 5 59 74 46 95 – Email: fleetdata@turbomeca.fr

Information concernant le matériel / Equipment information

Utilisateur

Customer

N° Appareil

Aircraft S/N

N/S - S/N Ref. - P/N TSN* TSO* CSN* CSO*

Moteur

Engine

Module M01 

déposé 

Removed 

module M01

Module M01 

installé 

Installed module 

M01

* TSN = Time Since New (Heures depuis neuf) TSO = Time Since Overhaul (Heures depuis RG)

CSN = Cycles Since New (Cycles depuis neuf) CSO = Cycles Since Overhaul (Cycles depuis RG)

Opération effectuée par / Work performed by:

Je certifie que le module M01 identifié ci-dessus a été installé selon les directives de ce SB Impératif.

I certify that the above-mentioned module has been fitted according to the directives given in this Mandatory SB.

Date [JJ/MMMM (en lettre)/AAAA 

ou/or DD/MMMM (letters)/YYYY] Nom / Name Fonction / Job title

ANNEXE 2.2 / APPENDIX 2.2

Signature:

END of section §2

"Application at the operator’s site or by a qualified Maintenance Center for level 1, 2"

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §3 - 1/1

3. APPLICATION BY A QUALIFIED MAINTENANCE CENTER FOR LEVEL 3

Not applicable.

Indeed, this check requires the sampling and analysis of oil with a significant number of operating hours in the 

engine, and this is not possible in a Maintenance Center, even during bench testing.

END of section §3

“Application by a qualified Maintenance Center for level 3”

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MANDATORY SERVICE BULLETIN

Applicable variants: ARRIEL 2 B - B1 - B1A - B1B - C - C1 - C2 - D - E - N - S1 - S2 §4 - 1/1

4. APPLICATION AT A TURBOMECA-APPROVED REPAIR CENTER

Not applicable.

Indeed, this check requires the sampling and analysis of oil with a significant number of operating hours in the 

engine, and this is not possible in a Repair Center, even during bench testing.

End of section §4

“Application by a TURBOMECA-approved Repair Center”

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