EASA AD No.: 2012-0071

EASA Form 110 Page 1/4 

## EASA AIRWORTHINESS DIRECTIVE

AD No.: 2012-0071

Date: 26 April 2012

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 participate in th e 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 be en sured by accomplishing any applicable ADs. Conseque ntly, no person may operate an aircraft to which an AD applies, except in accordan ce with the requirements of that AD, unless otherwi se 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, A rticle 14(4) exemption].


### Type Approval Holder’s Name : TURBOMÉCA Type/Model designation(s) :
ARRIEL 1 engines

TCDS Number: EASA.E.073

Foreign AD: Not applicable

Supersedure: This AD supersedes DGAC France AD 1990 -064(A) R1 dated 21 March 2001.



### ATA 72 Engine – Axial Compressor, Gas Generator Hollow Sha ft and Rear Bearing – Identification / Inspection / Cleaning / Replacement

Manufacturer(s): Turboméca S.A.

Applicability: ARRIEL 1A, 1A1, 1A2, 1B, 1C, 1C1, 1C 2, 1D, 1D1, 1E2, 1K, 1K1, 1S and 1S1 turbo-shaft engines, all serial numbers, except tho se incorporating Turboméca TU360 modification. These engines are known to be installed on, but not limited to, Eurocopter (formerly Eurocopter France, Aerospatiale) AS 350 B , BA, BB, B1and B2, and AS 365 N, Eurocopter Deutschland (formerly Messersc hmidt-Bölkow-Blohm) MBB-BK117-C1 and -C2, AgustaWestland (formerly Agus ta) A 109 K2, and Sikorsky S-76A helicopters.

Reason: Several cases have been reported of uncomma nded in-flight shut-down (IFSD) on ARRIEL 1 engines. Results of subsequent i nvestigations showed that engine operation in a dust laden atmosphere ma y lead to dust ingestion inside the engine, the possible consequences of whi ch are erosion of the air path components (mainly the axial compressor wheel) , and/or laterite deposit inside the gas generator hollow shaft which, in cas e of uneven distribution or detachment, can lead to an unbalanced condition of the gas generator rotating assembly and, ultimately, gas generator rear bearin g failure.
This condition, if not detected and corrected, coul d lead to an uncommanded engine in-flight shut down and may lead to an emerg ency landing. To address this potential unsafe condition, DGAC Fr ance issued AD 1990- 064(A), later revised to R1, to require periodic vi bration monitoring (Engine Maintenance Manual Chapter 05-10-03) and repetitive gas generator hollow shaft cleaning based on axial compressor erosion ch ecks. Since that AD was issued, in-service experience has shown that lateriteEASA AD No.: 2012-0071

EASA Form 110 Page 2/4 deposits inside the gas generator hollow shaft may be found when the axial compressor wheel has less erosion than initially as sessed. In addition, Turboméca have developed an improvement of the holl ow shaft (modification TU360), which makes the engine less susceptible to laterite deposits.
For the reasons described above, this AD requires t he determination of the engine history and operating conditions, and a one- time inspection of the axial compressor for erosion, in order to define the firs t cleaning of the Gas Generator hollow shaft. It also requires a repetiti ve cleaning of the shaft. Modification of an engine through Turboméca modific ation TU360 (which can be done during overhaul) constitutes terminating ac tion for the requirements of this AD.

Effective Date: 10 May 2012

Required Action(s) and Compliance Time(s): Required as indicated, unless accomplished previous ly: (1) Within 50 engine hours (EH) after the effective date of this AD, determine the engine history and operating conditions. If the engine operates, or has been operated, in dust laden atmosphere, or the operating history of the engine or Module 03 cannot be established, or doubt exists about the current operating conditions of the engine, within 50 EH after the effective date of this AD, inspect the axial compressor for e rosion in accordance with the instructions of paragraph 1.A.(1) and Figu re 2 of Turboméca Mandatory Service Bulletin (MSB) A292 72 0230 Versi on C.
Actions accomplished before the effective date of t his AD in accordance with the instructions of Turboméca MSB A292 72 0230 Issue 1 are acceptable to comply with the requirements of this paragraph. (2) Depending on the results of the inspection as r equired by paragraph (1) of this AD, determine the compliance times and acco mplish initial and repetitive cleanings of the gas generator hollow sh aft as specified in Appendix 1 of this AD. (3) If, during any of the cleanings as required by paragraph (2) of this AD, the dust weight collected inside the gas generator holl ow shaft is more than 8 grams, before next flight, replace the gas generato r rear bearing. Replacement of the gas generator rear bearing as re quired by this AD does not constitute terminating action for the repe titive cleaning. (4) After the effective date of this AD, if the hel icopter configuration is modified, or the type of mission or geographical op erating area changes, within 50 EH after such a change, accomplish the ac tions as specified in paragraph (1) of this AD. Depending on the results, accomplish all the actions as specified in paragraphs (2) and (3) of t his AD. (5) From the effective date of this AD, do not inst all a Module 03 (gas generator) on an engine unless it is in compliance with the requirements of this AD. (6) Modification of an engine through Turboméca mod ification TU360 constitutes terminating action for the requirements of this AD.

Ref. Publications: Turboméca MSB A292 72 0230 Versi on C dated 29 February 2012.
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 23 March 2012 as PAD 12-02 1 for consultation until 20 April 2012. The Comment Response Document can be found at http://ad.easa.europa.eu

. 3. Enquiries regarding this AD should be referred t o the Safety InformationEASA AD No.: 2012-0071

EASA Form 110 Page 3/4 Section, Executive 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 1 Customer Support, 40220 Tarnos, France, Fax: +33 5 59 74 45 15, or contact your usual or nearest Turboméca technical r epresentative at www.turbomeca-support.com

.EASA AD No.: 2012-0071

EASA Form 110 Page 4/4 

### Appendix 1 - Compliance Times for Initial and Repetitive Cleanings of the Gas Gen erator Hollow Shaft

Erosion of the Axial Compressor (See Note 1) Gas Generator (Module M03) and Axial Compressor (Module M02) are installed on the same Engine Compliance Time for the Initial Cleaning of the Gas Generator Hollow Shaft (see Note 2) Intervals for the Repetitive Cleanings of the Gas Generator Hollow Shaft (see Note 2)

Erosion rate is higher than 1 mm per 1 000 EH

or Total erosion is more than 3 mm Since equal or more than 200 EH Within 50 EH after the inspection of the erosion of the axial compressor

Refer to Figure 6 of Turboméca MSB A292 72 0230 Version C Since less than 200 EH, or unknown To be determined in accordance with Figure 3 of Turboméca MSB A292 72 0230 Version C (see Note 3) Erosion rate is lower than 1 mm per 1 000 EH and Total erosion is less than 3 mm Not relevant

Note 1: For inspection of the erosion of the Axial Compressor, refer to tasks 72-32-00-280-801 and 72- 32-00-280-802 of applicable Arriel 1 Maintenance Ma nuals (these tasks define acceptance criteria and maintenance actions following findings of erosion c heck). Note 2: Refer to paragraph 2.B ‘Operating Instructi ons’ and 2.D ‘Identification’ (for recording of the required periodicity) of Turboméca MSB A292 72 0230 Version C. Note 3: Two different methods may be used for deter mination of the compliance time: (1) “Lump” method:

• If take-off and/or landing is carried out in « bro wn-out » (= no visibility) condition :

 Within 50 EH after the inspection of the erosion o f the axial compressor

• If no take-off or landing is carried out in « brow n-out » condition :

 For single engine application: Within 150 EH after the inspection of the erosion of the axial compressor

 For twin engine application: Within 300 EH after t he inspection of the erosion of the axial compressor (2) “Counting” method: Time calculated in function of flight condition parameters.