EASA AD No : 2006-0368R1

EASA Form 110 Page 1/4 

## EASA AIRWORTHINESS DIRECTIVE

AD No.: 2006-0368R1 Corrected: 08 December 2010

Date: 02 December 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 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 accor dance with the requirements of that AD unless other wise specified by the Agency [EC 2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/200 8, Article 14(4) exemption]. 

### Type Approval Holder’s Name :
EUROCOPTER Type/Model designation(s) :

SA 365 N , AS 365 N, SA 366 and EC 155 helicopters

TCDS Number: France N° 159

Foreign AD: Not applicable

Revision: This AD revises EASA AD 2006-0368-E date d 06 December 2006.



### ATA 62 Rotor – Rotor Mast Nut – Check / Replacement

Manufacturer(s): EUROCOPTER (Formerly EUROCOPTER – FRANCE, AEROSPATIALE)

Applicability: SA 365 N, SA 365 N1, AS 365 N2, AS 3 65 N3, SA 366 G1, EC 155 B and EC 155 B1 helicopters, all serial numbers, fitted w ith a mast nut Part Number (P/N) 360A31-1020-20 installed in main rotor mast a ssemblies.
Note: This AD does not apply to helicopters that have mod ifications (MOD) 0762B88 and/or MOD 0762C42 embodied in-production or EUROCO PTER Service Bulletin No. 62-007 embodied in service as applicab le to helicopter type. Embodiment of these modifications consists in repla cement of mast nut P/N 360A31-1020-20 by mast nut P/N 365A31-2060-20 or P/ N 365A31-2060-21, as applicable to helicopter type.

Reason: A cracked (partially failed) main rotor mas t nut was discovered during a complete overhaul of a main rotor mast. The start o f the crack was related to circular scoring found in the nut threads. This condition, if not detected and corrected, coul d lead to complete failure of the mast nut, possibly resulting in failure of the rotor mast and consequent loss of control of the helicopter.
To address this unsafe condition, EASA issued Emerg ency AD 2006-0368-E to require repetitive inspections of the mast nut and, depending on findings, corrective actions.EASA AD No : 2006-0368R1

EASA Form 110 Page 2/4 Since issuance of EASA AD 2006-0368-E, EUROCOPTER h as developed MOD 0762C42 to improve the strength of the mast nut by changing its material. The embodiment of MOD 0762C42 or the in-service rep lacement of mast nut P/N 360A31-1020-20 by mast nut P/N 365A31-2060-20 o r P/N 365A31-2060- 21 (as applicable to helicopter type) constitutes a n optional terminating action to the repetitive inspection requirements of this AD. For this reason, EASA AD 2006-0368-E is revised to inform which helicopters remain subject to inspections and replacement requirements of this AD

. This AD is republished to correct a typographical e rror in the replacement mast nut part numbers referenced in this AD.

Effective Date: Revision 1: 16 December 2010. Original issue: 08 December 2006.
Required action(s) and Compliance Time(s): The following measures are rendered mandatory from 08 December 2006 [the effective date of the original issue of this AD]: (1) SA 365 N, SA 365 N1, AS 365 N2 and AS 365 N3 he licopters. (1.1) .Main rotor mast assemblies having logged less than 1,600 flight hours since new or complete overhaul. At the latest at 1,650 flight hours since new or c omplete overhaul, then at intervals not exceeding 1,650 flight hours, inspect the mast nut using a light source or a borescope if MOD 0762B33 or MOD 0762B69 is not embodied or using a borescope if MOD 0762B33 or MOD 0762B69 is embodied, to ensure that there is no crack or failure in the mas t nut, in compliance with the instructions specified in paragraph 2.B of EURO COPTER AS 365 Alert Service Bulletin (ASB) No. 62.00.23 referenced belo w. (1.2) . Main rotor mast assemblies having logged more than 1,600 flight hours since new or complete overhaul: No later than within 50 flight hours, then at inte rvals not exceeding 1,650 flight hours, inspect the mast nut using a light source or a borescope if MOD 0762B33 or MOD 0762B69 is not embodied or using a borescope if MOD 0762B33 or MOD 0762B69 is embodied, to ensure t hat there is no crack or failure in the mast nut, in compliance wit h the instructions specified in paragraph 2.B of EUROCOPTER AS 365 ASB No. 62.00 .23 referenced below. (2) SA 366 G1 helicopters: (2.1 ) Main rotor mast assemblies having logged less than 960 flight hours since new or complete overhaul: At the latest at 990 flight hours since new or com plete overhaul, then at intervals not exceeding 990 flight hours , inspect the mast nut using a light source or a borescope if MOD 0762B33 or MOD 0762B69 is not embodied or using a borescope if MOD 0762B33 or MOD 0762B69 is embodied, to ensure that there is no crack or failure in the mas t nut, in compliance with the instructions specified in paragraph 2.B of EURO COPTER SA 366 ASB No. 62.12 referenced below. (2.2) . Main rotor mast assemblies having logged more than 960 flight hours since new or complete overhaul: No later than within 30 flight hours, then at inte rvals not exceeding 990 flight hours , inspect the mast nut using a light source or a bor escope if MOD 0762B33 or MOD 0762B69 is not embodied or using a borescope if MOD 0762B33 or MOD 0762B69 is embodied, to ensure that there is no crack or failure in the mast nut, in compliance with the instructions speci fied in paragraph 2.B of EUROCOPTER SA 366 ASB No. 62.12 referenced below.EASA AD No : 2006-0368R1

EASA Form 110 Page 3/4 (3) EC 155 B and EC 155 B1 helicopters: (3.1) Main rotor mast assemblies (pre MOD 0762B88 or not modified in accordance with SB No. 62-007), having logged less than 610 flight hours since new: At the latest at 660 flight hours since new, then at intervals not exceeding 660 flight hours, inspect the mast nut using a bore scope to ensure that there is no crack or failure in the mast nut, in co mpliance with the instructions specified in paragraph 2.B of EUROCOPT ER EC 155 Alert Service Bulletin (ASB) No. 62A014 referenced below. ( 3.2) Main rotor mast assemblies (pre MOD 0762B88 or not modified in accordance with SB No. 62-007), having logged more than 610 flight hours since new: No later than within 50 flight hours, then at inte rvals not exceeding 660 flight hours, inspect the mast nut using a borescop e to ensure that there is no crack or failure in the mast nut, in compliance with the instructions specified in paragraph 2.B of EUROCOPTER EC 155 Ale rt Service Bulletin (ASB) No. 62A014 referenced below. (4) Interpretation of the results: (4.1) If, during any of the inspections as required by this AD, a crack / failure is found in the mast nut, before next fligh t, remove and replace the rotor mast nut, in accordance with the instructions specified in paragraph 2.B.2 of the referenced ASB corresponding to the he licopter version. (4.2) Replacement of the mast nut as required by pa ragraph (4.1) of this AD does not constitute terminating action for the r epetitive inspections required by this AD. (5) Optional terminating action: Modification of a helicopter by replacing rotor mas t nut P/N 360A31-1020- 20 with rotor mast nut P/N 365A31-2060-20 or P/N 36 5A31-2060-21, as applicable to helicopter type, constitutes terminat ing action for the repetitive inspection requirements of this AD for that helicop ter.

Ref. Publications: EUROCOPTER AS 365 Alert Service Bulletin No. 62.00.23 original issue dated 22 November 2006 and revision 1 dated 27 October 20 10,
EUROCOPTER SA 366 Alert Service Bulletin No. 62.12 original issue dated 22 November 2006 and revision 1 dated 27 October 2010,
EUROCOPTER EC 155 Alert Service Bulletin No. 62A014 original issue dated 22 November 2006 and revision 1 dated 27 October 20 10, EUROCOPTER EC 155 Service Bulletin No. 62-007 origi nal issue dated 02 March 2006. The use of later approved revisions of these docume nts is acceptable for compliance with the requirements of this AD.

Remarks : 1. If requested and appropriately substantiated, E ASA can approve Alternative Methods of Compliance for this AD. 2. The required actions and the risk allowance have granted the issuance of a Final AD with Request for Comments, postponing the public consultation process after publication. 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

.EASA AD No : 2006-0368R1

EASA Form 110 Page 4/4 4. For any question concerning the technical conten t of the requirements in this AD, please contact: EUROCOPTER (STDI) - Aéropo rt de Marseille Provence 13725 Marignane Cedex - France. Tel: 33 (0 ) 4 42 85 97 97 - Fax: 33 (0) 4 42 85 99 66. E-mail: Directive.technical-support@eurocopter.com

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