EASA AD No.: 2010-0198

EASA Form 110 Page 1/2 

## EASA AIRWORTHINESS DIRECTIVE

AD No.: 2010-0198

Date: 01 October 2010

Note: This Airworthiness Directive (AD) is issued b y EASA, acting in accordance with Regulation (EC) No 216/2008 on behalf of the Europe an Community, its Member States and of the European third countries that participat e in the activities of EASA under Article 66 of that Regulation.
This AD is issued in accordance with EC 1702/2003, Part 21A.3B. In accordance with EC 2042/2003 Annex I, Part M.A.301, the continuing airworthiness of an aircraft shall b e ensured by accomplishing any applicable ADs. Cons equently, no person may operate an aircraft to which an AD applies, exc ept in accordance with the requirements of that AD, unless otherwise specified by the Agency [EC 2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/2008, Article 14(4) exemption].


### Type Approval Holder’s Name :
Turboméca Type/Model designation(s) :
ARRIEL 2 series turboshaft engines

TCDS Number : EASA.E.001

Foreign AD : Not applicable

Supersedure : None



### ATA 72 Engine – Module M03 (Gas Generator) – Turbine Blade – Modification

Manufacturer(s): Turboméca S.A.
Applicability: Arriel 2B, 2B1, 2B1A turboshaft engi nes, if not modified by TU166 modification. These engines are known to be installed on, but not limited to: Eurocopter AS 350 B3, EC 130 B4 helicopters and Cha nghe Z11 helicopters.
Reason: Several cases of Gas Generator (GG) Turbine Blade rupture occurred in service on ARRIEL 2 twin engine applications and re cently one on a single engine helicopter. For the case occurring in flight on a single engine helicopter (ARRIEL 2B1 engine), the pilot performed an emergency autorotation, landing the helicopter without furthe r incident. The design of ARRIEL 2 engines (containment shield around the GG turbine) allows debris from a blade or the disc int er-blade area to be contained in the event of rupture. However, the rup ture of a GG Turbine Blade may lead to an uncommanded In Flight Shut-Dow n which, on a single-engine helicopter, could ultimately lead to an emergency autorotation landing. The most probable root cause of the ruptures is an excitation of one of the vibration modes of the GG Turbine Blade in conjunct ion with several secondary contributing factors which are deemed suf ficient to reduce the stress margin of the blade to a level consistent wi th the rate of occurrencesEASA AD No.: 2010-0198

EASA Form 110 Page 2/2 of ruptures encountered.
Turboméca has released TU166 modification which con sists in inserting Blade dampers between the GG Turbine Disc and the G G Turbine Blade platform. Introduction of these dampers minimizes t he effects of HP blade vibratory excitation and increases the blade tolera nce for this type of stress. For the reasons stated above, this AD requires the accomplishment of TU166 modification on ARRIEL 2 single engine applic ations.
After the issuance of EASA PAD 10-094 related to th is AD, Turboméca has issued Turboméca Mandatory Service Bulletin (MSB) A 292 72 3166 version B.

Effective Date: 15 October 2010

Required Action(s) and Compliance Time(s): Required as indicated, unless accomplished previous ly: (1) Accomplish TU166 modification in accordance wit h the instructions specified within Turboméca Mandatory Service Bullet in (MSB) A292 72 3166 version B: when the GG Turbine is replaced (at approved Operat or or Service Center)

or when the engine or Module M03 is going through over haul or repair (at approved Maintenance or Repair Center), whichever occurs first, but no later than 25 months after the effective date of this AD. (2) Accomplishment, before the effective date of th is AD, of TU166 modification in accordance with the instructions of Turboméca MSB A292 72 3166 version A is acceptable for compliance with the requirement of paragraph (1) of this AD.
Ref. Publications: Turboméca Mandatory Service Bull etin (MSB) A292 72 3166 version B dated 20 September 2010. The use of later approved revisions of this documen t is acceptable for compliance with the requirements of this AD.

Remarks : 1. If requested and appropriately substantiated, EA SA can approve Alternative Methods of Compliance for this AD. 2. This AD was posted on 31 August 2010 as PAD 10-0 94 for consultation until 28 September 2010. No comments w ere received during the consultation period. 3. Enquiries regarding this AD should be referred t o the Airworthiness Directives, Safety Management & Research Section, C ertification Directorate, EASA. E-mail: ADs@easa.europa.eu

. 4. For any question concerning the technical conten t of the requirements in this AD, please contact: Turboméca, S.A. ARRIEL 2 Customer Support 40220 Tarnos, France Fax: +33 5 59 74 45 15 or your usual or nearest Tur boméca technical representative at www.turbomeca-support.com