EASA AD No.: 2013-0225-E

TE.CAP.00111-003 © European Aviation Safety Agency. All rights reserved. 1/2

Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet.

EASA EMERGENCY AIRWORTHINESS DIRECTIVE

AD No.: 2013-0225-E

Date: 20 September 2012

Note: This Emergency Airworthiness Directive (AD) is issued by EASA, acting in accordance 

with Regulation (EC) No 216/2008 on behalf of the European Community, its Member States 

and of the European third countries that participate in the activities of EASA under Article 66 of 

that Regulation.

This AD is issued in accordance with EU 748/2012, Part 21.A.3B. In accordance with EC 2042/2003 Annex I, Part M.A.301, the 

continuing airworthiness of an aircraft shall be ensured by accomplishing any applicable ADs. Consequently, no person may operate an 

aircraft to which an AD applies, except 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].

Design Approval Holder’s Name :

AGUSTAWESTLAND S.p.A.

Type/Model designation(s) :

A109, AW109, A119 and AW119 helicopters

TCDS Number: EASA.R.005

Foreign AD: Not applicable

Supersedure: None

ATA 64 Tail Rotor – Tail Rotor Drive Shaft Line Nut – Inspection

Manufacturer(s): AgustaWestland S.p.A (formerly Agusta S.p.A.).

Applicability: A109A, A109AII and A109C helicopters, all serial numbers (S/N);

A109E helicopters, all S/N up to S/N 11832 inclusive, except S/N 11796, from 

11808 to S/N 11810 inclusive and from S/N 11812 to 11829 inclusive;

A109K2 helicopters, all S/N;

A109LUH helicopters, all S/N;

A109S helicopters, all S/N;

AW109SP helicopters, all S/N up to S/N 22316 inclusive, except S/N 22284, 

22286, 22307 and 22308;

A119 and AW119MKII helicopters, all S/N up to AW119MKII S/N 14811

inclusive, except 14805 and 14807.

Reason: Occurrences were reported of two in-service AW109SP helicopters, where 

during scheduled inspection on the tail rotor drive shaft line, one nut Part 

Number (P/N) MS21042L4 that connects the Thomas coupling with the splined 

adapter was found cracked.

The subsequent technical investigation identified that the reported cracks of 

the nuts are the results of a production deficiency (causing hydrogen 

embrittlement) at the nut supplier.

This condition, if not detected and corrected, could lead to failure of the tail 

rotor function, resulting in loss of control of the helicopter.
EASA AD No.: 2013-0225-E

TE.CAP.00111-003 © European Aviation Safety Agency. All rights reserved. 2/2

Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet.

To address this unsafe condition, AgustaWestland issued seven Bollettino 

Tecnico (BT), BT 109EP-130, BT 109-136, BT 109K-58, BT 109L-066, BT 

109S-055, BT 109SP-069 and BT 119-61 for all helicopters that are potentially 

affected.

For the reasons described above, this AD requires a one-time inspection of

each P/N MS21042L4 nut installed on the tail rotor drive shaft line and

replacement of each affected nut with a serviceable part having a different 

P/N.

Effective Date: 21 September 2013

Required Action(s) 

and Compliance 

Time(s):

Required as indicated, unless accomplished previously:

(1) Before next flight after the effective date of this AD, inspect each nut P/N 

MS21042L4 and, within the compliance time specified in Table 1 of this 

AD, depending on findings, as applicable, replace each nut P/N 

MS21042L4 with a serviceable part in accordance with the instructions of 

the applicable BT.

Note: For the purpose of this AD, the applicable BT is the one mentioned in 

Ref. Publications of this AD for the affected helicopter model.

Table 1 – Nut replacement

Finding Compliance time

Nut is cracked Before next flight

Nut is not cracked Within 10 flight hours or 30 days, 

whichever occurs first after the 

effective date of this AD

(2) From the effective date of this AD, do not install a nut having a P/N 

MS21042L4 on the tail rotor drive shaft line of any helicopter.

Ref. Publications: AgustaWestland BT 109EP-130 dated 20 September 2013.

AgustaWestland BT 109-136 dated 20 September 2013.

AgustaWestland BT 109K-58 dated 20 September 2013.

AgustaWestland BT 109L-066 dated 20 September 2013.

AgustaWestland BT 109S-055 dated 20 September 2013.

AgustaWestland BT 109SP-069 dated 20 September 2013.

AgustaWestland BT 119-61 dated 20 September 2013.

The use of later approved revisions of these documents is acceptable for 

compliance with the requirements of this AD.

Remarks : 1. If requested and appropriately substantiated, EASA can approve 

Alternative Methods of Compliance for this AD.

2. The results of the safety assessment have indicated the need for 

immediate publication and notification, without the full public consultation 

process.

3. Enquiries regarding this AD should be referred to the Safety Information 

Section, Executive Directorate, EASA. E-mail: ADs@easa.europa.eu.

4. For any question concerning the technical content of the requirements in 

this AD, please contact: Agusta S.p.A. Customer Support

Via del Gregge, 100 - 21015 Lonate Pozzolo (VA) – Italy

Telephone + 39 0331 664600 ; Fax: + 39 0331 664684

E-mail: custserv@agustawestland.com.