40220 Tarnos - France 

Tel. +33 (0)5 59 74 40 00 - Telex 570 042 - Fax +33 (0)5 59 74 45 15

MANDATORY SERVICE BULLETIN 

 

ARRIEL 2 No. 292 73 2812

Subject: Visual inspection of adjusted Hydromechanical Metering 

Unit (HMU) drive-link splines. 

The technical information contained in this document has been approved 

under the Design Organization Approval No. EASA.21J.070.

Version: G 

Reason for update: Reinforcement of the compliance code and 

conditions. 

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MANDATORY SERVICE BULLETIN 

1. Compliance 

SB effectivity date * JULY 2003 

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

according to the conditions of application. 

This date corresponds to when all resources needed to perform the procedure (parts, tools, 

documentation, etc.) will be available. 

If these resources are available any earlier, the SB may, as an exception, be applied prior to the 

effectivity date. 

CAUTION: FAILURE TO APPLY THIS MANDATORY SERVICE BULLETIN MAY LEAD TO AN 

UNCOMMANDED IN-FLIGHT ENGINE SHUT-DOWN WHICH, ON A SINGLE-ENGINE 

HELICOPTER, LEADS TO AN EMERGENCY AUTOROTATION LANDING. 

A. Compliance 

Application of this Mandatory Service Bulletin (SB) is considered mandatory as a result of a 

technical requirement which might affect flight safety. It may be done immediately or to 

accommodate an existing schedule. 

Validity Code 

ARRIEL 2B - 2B1 - 2B1A - 2B1B 1-A 

Note: variants 2C, 2C1, 2C2, 2S1 and 2S2 are addressed in Mandatory SB 

No. 292 73 2822. 

Conditions of application for engines in service 

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

The purpose of this Mandatory SB is to inspect HMU splines after 500 operating hours of 

HMU/current M01 assembly. If the result is compliant after 500 operating hours and 

providing that HMU/current M01 assembly remains unchanged, it will never again be 

necessary to inspect splines. 

A new inspection will only be performed (even if the SB was already applied) in the 

following cases: 

 HMU is removed from current M01 and installed on another M01 or 

 M01 is replaced or 

 HMU is repaired / overhauled (given that the splines can be replaced during 

repair/level 4 overhaul). 

To determine the operating hours logged by the HMU/current M01 assembly: 

 Check HMU log card to see the date that the HMU began operating on this engine. 

 On engine log book, check that M01 was not replaced since this date. 

 Check HMU log card to know if it was overhauled/repaired since it operated on 

current M01. 

 Determine the total operating hours logged by the M01/HMU assembly: 

o since HMU first operated on current M01 or 

o since HMU repair/overhaul. 

The compliance conditions of this Mandatory SB and the associated deadlines are 

shown in the table on the following page. 

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MANDATORY SERVICE BULLETIN 

Note: In accordance with Maintenance Manual, task 73-23-00-900-801, visual inspection of 

drive-link splines must be performed each time the adjusted HMU is removed/installed. 

(2) At a TURBOMECA-approved Repair Center 

Application before delivery 

Is it installed on 

the engine? 

HMU 

How many operating 

hours* ?

> 500 operating hours* Less than 500 

operating hours * 

Task(s) to be performed: 

Submit compliance certificate 

for previous inspection 

(If available and not already returned) 

Task(s) to be performed: 

Visual inspection of adjusted HMU drive-link splines 

And 

 Submission of results according to appendices of this Mandatory SB 

Deadline: 

Within 25 operating hours 

of receiving 

version G of 

this Mandatory SB 

Deadline: 

Between 500 and 525 

operating hours * 

Was the SB (all versions) 

applied after HMU logged 500 

operating hours*? No

Yes 

Deadline: 

Upon receiving version G of this 

Mandatory SB 

Perform inspection 

before installation 

according to task 

73-23-00-900-801 of the 

Maintenance Manual 

(no need to return results 

according to appendices 

of this Mandatory SB) 

Yes No 

Once installed 

on M01 

* Operating hours logged by the HMU/ current M01 

assembly. 

Note: If HMU was repaired/overhauled since first operating 

on current module M01, operating hours since repair/ 

overhaul must be taken into account. 

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MANDATORY SERVICE BULLETIN 

B. Purpose 

CAUTION: FAILURE TO APPLY THIS MANDATORY SERVICE BULLETIN MAY LEAD TO AN 

UNCOMMANDED IN-FLIGHT ENGINE SHUT-DOWN WHICH, ON A SINGLE-ENGINE 

HELICOPTER, LEADS TO AN EMERGENCY AUTOROTATION LANDING. 

To avoid an uncommanded in-flight engine shut-down caused by damage to the adjusted 

HMU drive-link splines. 

C. Description 

Visual inspection to check the condition of the HP pump drive gear shaft splines, cleaning 

and inspection of the sleeve assembly splines. 

D. Approval 

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

Organization Approval No. EASA.21J.070. 

This Mandatory SB is subject to an Airworthiness Directive. 

E. Manpower 

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

(a) Personnel: 1 mechanic. 

(b) Time required: 1 man-hour. 

(2) At a TURBOMECA-approved Repair Center 

(a) Personnel of approved Repair Center. 

(b) Time determined by the Repair Center as being appropriate for this level of 

intervention. 

F. Material 

Refer to paragraph 3. 

G. Tooling 

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

Mechanic's standard tooling. 

(2) At a TURBOMECA-approved Repair Center 

Refer to the relevant ARRIEL 2 Overhaul Manual or Component Maintenance Manual. 

H. Weight and balance 

Not applicable. 

I. References 

(1) ARRIEL 2B Maintenance Manual................................................ Ref. X 292 M5 450 2. 

(2) ARRIEL 2B1 Maintenance Manual.............................................. Ref. X 292 N5 450 2. 

(3) ARRIEL 2B1A Maintenance Manual ........................................... Ref. X 292 P4 450 2. 

(4) ARRIEL 2B Overhaul Manual...................................................... Ref. X 292 M5 500 2. 

(5) ARRIEL 2B1 - 2B1A Overhaul Manual........................................ Ref. X 292 N5 500 2. 

(6) ARRIEL 2B Component Maintenance Manual ............................ Ref. X 73 23 03 2. 

(7) ARRIEL 2B1 - 2B1A Component Maintenance Manual .............. Ref. X 73 23 05 2. 

(8) Relevant Helicopter Maintenance Manual. 

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MANDATORY SERVICE BULLETIN 

J. Other publications concerned 

(1) ARRIEL 2B Spare Parts Catalog........................................... Ref. X 292 M5 700 2. 

(2) ARRIEL 2B1 Spare Parts Catalog......................................... Ref. X 292 N5 700 2. 

(3) ARRIEL 2B1A Spare Parts Catalog ...................................... Ref. X 292 P4 700 2. 

(4) ARRIEL 2B Illustrated Parts Catalog..................................... Ref. X 292 M5 600 2. 

(5) ARRIEL 2B1 Illustrated Parts Catalog................................... Ref. X 292 N5 600 2. 

(6) ARRIEL 2B1A Illustrated Parts Catalog ................................ Ref. X 292 P4 600 2. 

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MANDATORY SERVICE BULLETIN 

2. Instructions to be incorporated 

A. Implementation 

This inspection may be performed without removing the engine from the helicopter. 

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

Remove adjusted HMU. 

(2) At a TURBOMECA-approved Repair Center 

Remove adjusted HMU. 

B. Operating instructions (see Figure)

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

(a) Remove adjusted HMU: refer to relevant ARRIEL 2 Maintenance Manual, 

task 73-23-00-900-801. 

(b) Inspect adjusted HMU: refer to relevant ARRIEL 2 Maintenance Manual, 

task 73-23-00-200-802. 

(c) Complete Appendix 3 according to the findings. Indicate the damage type and 

location. 

(d) In case of anomaly, contact TURBOMECA to confirm removal of the HMU or sleeve 

assembly. Provide as many details as possible on the damage type (description and 

photos). 

CAUTION: FAILURE TO CLIP THE SLEEVE ASSEMBLY ONTO THE DRIVE GEAR 

SHAFT MAY LEAD TO UNCOMMANDED IN-FLIGHT ENGINE 

SHUT-DOWN. 

(e) Install adjusted HMU: refer to relevant ARRIEL 2 Maintenance Manual, 

task 73-23-00-900-801. 

(2) At a TURBOMECA-approved Repair Center 

Refer to the relevant ARRIEL 2 Component Maintenance Manual and complete 

Appendix 3 of this Mandatory SB in order to determine and specify the type and location 

of any found anomalies. 

C. Reconditioning and checks 

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

Perform a ground run check: refer to relevant ARRIEL 2 Maintenance Manual, task 

71-02-13-280-801. 

Note: Perform a visual leak check of adjusted HMU. 

(2) At a TURBOMECA-approved Repair Center 

Refer to relevant ARRIEL 2 Overhaul Manual, chapter 72-00-00. 

D. Identification 

(1) At the operator's site, at a TURBOMECA-approved Service Center or at a 

TURBOMECA-approved Maintenance Center 

(a) Complete the current or unique engine log book as follows: 

- Record the application of this Mandatory SB on the log card of the inspected 

adjusted HMU. 

(b) Notify TURBOMECA that this Mandatory SB has been applied by returning the fully 

completed compliance certificate (Appendix 1) and the detailed results recorded in 

Appendix 3 of this Mandatory SB. 

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MANDATORY SERVICE BULLETIN 

(c) If replacing adjusted HMU: 

1 Complete the current or unique engine log book as follows: 

1.1 Section "C": record the replacement of the adjusted HMU. 

1.2 Update the log card of the removed adjusted HMU and the log card of the 

installed adjusted HMU. 

1.3 Section "E": record the replacement of the adjusted HMU. 

2 Notify TURBOMECA that the adjusted HMU has been replaced by returning the 

fully completed compliance certificate (Appendix 2 of this Mandatory SB). 

(2) At a TURBOMECA-approved Repair Center 

(a) Complete the following sections in the unique engine log book: 

- Record the application of Mandatory SB No. 292 73 2812, on the log card of the 

inspected adjusted HMU. 

(b) Notify TURBOMECA that this Mandatory SB has been applied by returning the fully 

completed compliance certificate (Appendix 1). 

E. Routine maintenance 

Not applicable. 

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MANDATORY SERVICE BULLETIN 

3. Material information 

A. Basic information 

The parts list (provided below) required for the application of this Mandatory SB is for one 

engine. 

B. List of parts 

Refer to relevant ARRIEL 2 Maintenance Manual for the spare parts related to installation of 

the adjusted HMU. 

New 

Part Number Key Qty Name Price Old Part Number Key Qty 

0 319 91 134 0 B 1 Retaining ring * 

* Prices available upon request. 

Key 

B - Part not incorporated by this inspection, but required for the inspection to be performed. 

C. Supply conditions 

Order supplies as needed from: 

your local TURBOMECA Support Center 

or 

TURBOMECA 

Direction Support Ventes Opérateurs 

Département Commercial 

40220 TARNOS 

France 

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

 SB_292_73_2812_EN - G <June 24, 2013> - 8 / 14
MANDATORY SERVICE BULLETIN 

Jonc

Ring

Cannelures

Splines

Manchon complet

Sleeve assembly

Manchon

Sleeve

Jonc

Ring

FIGURE 

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MANDATORY SERVICE BULLETIN 

Objet : Attestation d’application du SB Impératif n° 292 73 2812. 

Subject: Mandatory SB No. 292 73 2812 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 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 Réf. - P/N TSN* TSO* CSN* CSO*

Moteur 

Engine 

Ensemble pompes 

HP/BP doseur 

contrôlé 

Inspected HMU 

 

* 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:

Résultats du contrôle (cocher la case correspondante)

Inspection result: check the corresponding box

Conforme 

Compliant 

Non conforme

Not compliant

Manchon d’accouplement (cannelures mâles) 

Coupling sleeve (male splines)

Manchon d’accouplement (cannelures femelles) 

Coupling sleeve (female splines)

Cannelures mâles de l’arbre pignon menant pompe HP 

HP pump drive gear shaft male splines

Je certifie que l'ensemble pompes HP/BP doseur réglé identifié ci-dessus a été contrôlé selon les 

directives de ce SB Impératif. 

I certify that the above-mentioned adjusted HMU has been inspected according to the directives given in this 

Mandatory SB. 

Date [JJ / MMMM (en lettre) / AAAA 

or DD / MMMM (letter) / YYYY] Nom / Print name Fonction / Job title

 

ANNEXE 1 / APPENDIX 1 

Signature : 

 SB_292_73_2812_EN - G <June 24, 2013> - 10 / 14
MANDATORY SERVICE BULLETIN 

Objet : Attestation de remplacement de l'ensemble pompes HP/BP 

doseur réglé.

Subject: Compliance certificate for replacement of adjusted HMU. 

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 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 Réf. - P/N TSN* TSO* CSN* CSO*

Moteur

Engine 

Ensemble pompes 

HP/BP doseur réglé 

déposé 

Removed adjusted HMU 

 

Ensemble pompes 

HP/BP doseur réglé 

posé 

Installed adjusted HMU

 

* 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 l'ensemble pompes HP/BP doseur réglé identifié ci-dessus a été installé selon les 

directives de ce SB Impératif. 

I certify that the above-mentioned adjusted HMU has been installed according to the directives given in this 

Mandatory SB. 

Date [JJ / MMMM (en lettre) / AAAA 

or DD / MMMM (letter) / YYYY] Nom / Print name Fonction / Job title

 

ANNEXE 2 / APPENDIX 2 

Signature : 

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MANDATORY SERVICE BULLETIN 

Objet : Feuilles de résultats du SB Impératif n° 292 73 2812.

Subject: Mandatory SB No. 292 73 2812 result sheets. 

Important / Important notice : Après application des instructions spécifiées dans ce SB Impératif, veuillez compléter la présente 

feuille de résultats et la retourner par courrier ou courriel ou fax à : 

After application of the instructions specified in this Mandatory SB, please complete this result sheet and 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 Réf. - P/N TSN* TSO* CSN* CSO*

Moteur 

Engine 

Module M01 

Ensemble pompes 

HP/BP doseur 

réglé contrôlé 

Inspected adjusted 

HMU

 

Depuis que le HMU opère sur le M01 

actuel 

Since HMU operates on current M01

Heures de fonctionnement du 

couple HMU / M01 

Operating hours logged on current 

HMU / M01 assembly 

Depuis réparation/révision du HMU 

Since repair/overhaul of the HMU

* 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:

Type et localisation des endommagements / Type and location of damage 

- Cannelures de l’arbre pignon menant de la pompe HP / HP pump drive gear shaft splines 

Localisation des constatations : 01 cannelures / Finding location: 01 splines

 SB_292_73_2812_EN - G <June 24, 2013> - 12 / 14
MANDATORY SERVICE BULLETIN 

Conforme 

Compliant 

Non conforme 

Not compliant 

Résultats du contrôle (cocher la case correspondante) 

Inspection result: check the corresponding box Absence 

No trace

Présence 

acceptable 

Acceptable 

trace

Présence inacceptable

Unacceptable trace

Corrosion / Corroded 

Impact / Impact 

Ecaillage / Scaling 

Arrachement / Stripped 

Usure de frottement perceptible au toucher / Fretting perceptible 

by touch 

Autre / other

- Cannelures mâles du manchon complet / Sleeve assembly male splines 

Localisation des constatations: 02 cannelures / Finding location: 02 splines 

Conforme 

Compliant 

Non conforme 

Not compliant 

Résultats du contrôle (cocher la case correspondante) 

Inspection result: check the corresponding box Absence 

No trace

Présence 

acceptable 

Acceptable 

trace

Présence inacceptable

Unacceptable trace

Corrosion / Corroded 

Impact / Impact 

Ecaillage / Scaling 

Arrachement / Stripped 

Usure de frottement perceptible au toucher / Fretting perceptible 

by touch 

Autre / other

 SB_292_73_2812_EN - G <June 24, 2013> - 13 / 14
MANDATORY SERVICE BULLETIN 

- Cannelures femelles du manchon complet / Sleeve assembly female splines 

Localisation des constatations: 03 cannelures / Finding location: 03 splines 

Conforme 

Compliant 

Non conforme 

Not compliant 

Résultats du contrôle (cocher la case correspondante) 

Inspection result: check the corresponding box Absence 

No trace

Présence 

acceptable 

Acceptable 

trace

Présence inacceptable

Unacceptable trace

Corrosion / Corroded 

Impact / Impact 

Ecaillage / Scaling 

Arrachement / Stripped 

Usure de frottement perceptible au toucher / Fretting perceptible 

by touch 

Autre / other

ANNEXE 3 / APPENDIX 3 

Signature : 

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