EASA AD No.: 2015-0155

TE.CAP.00110-004 © European Aviation Safety Agency. All rights reserved. 1/2

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

EASA AIRWORTHINESS DIRECTIVE

AD No.: 2015-0155

Date: 28 July 2015

Note: This 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 EU 1321/2014 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

[EU 1321/2014 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) :

AB139 and AW139 helicopters

TCDS Number : EASA.R.006

Foreign AD : Not applicable

Supersedure : None

ATA 30 Ice and Rain Protection– Full Ice Protection System Tail Rotor Slip

Ring – Inspection / Replacement

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

Corporation (formerly Agusta Aerospace Corporation).

Applicability: AB139 and AW139 helicopters, all serial numbers (S/N), if equipped with Full 

Icing Protection System (FIPS).

Note 1: Helicopters equipped with FIPS and have one of the kits “Partial 

Removal Arrangement” with Part Number (P/N) from 4G3000F00311 to P/N 

4G3000F00319 inclusive are affected by the requirements of this AD.

Reason: A report was received that, during an inspection accomplished on the tail rotor 

(TR) slip ring of an AW139 helicopter, the TR slip ring body was found

detached from the supporting flange. The screws connecting the mounting 

flange and the slip ring body were found loose and broken. A similar event was 

reported on another AW139 helicopter where, during a scheduled inspection,

three screws were found missing from the TR slip ring, which was partially 

loose from the tail rotor gearbox support.

Subsequent technical investigation revealed that the torque of the screws was 

improperly low. The TR slip ring manufacturer established that this had been 

caused on the production line by improper installation of the affected screws on 

a number of TR slip rings.

This condition, if not detected and corrected, could lead to other events of 

detachment of the TR slip ring, possibly resulting in reduced control of the 

helicopter.
EASA AD No.: 2015-0155

TE.CAP.00110-004 © 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 potential unsafe condition, AgustaWestland (AW) published 

Bollettino Tecnico (BT) 139-404, providing inspection and replacement 

instructions for the affected TR slip rings.

For the reasons described above, this AD requires identification and a 

one-time inspection of the affected slip rings and, depending on findings, 

accomplishment of applicable corrective action(s).

Effective Date: 11 August 2015

Required Action(s) 

and Compliance

Time(s):

Required as indicated, unless accomplished previously:

Note 2: For the purpose of this AD, an affected TR slip ring has a P/N 

4G6420V00151 or P/N 4G6420V00152 or P/N 4G6420V00153, except if this 

TR slip ring has a “T” marked after the S/N, or if “MOD 1” is marked on the 

manufacturing (MFG) plate.

(1) Within 14 days after the effective date of this AD, inspect each affected TR 

slip ring in accordance with the instructions of AgustaWestland BT 

139-404.

(2) If, during the inspection as required by paragraph (1) of this AD, no

discrepancy is found on a TR slip ring, before next flight, replace the 

mounting screws, re-install the lockwire and re-identify the TR slip ring in 

accordance with the instructions of AgustaWestland BT 139-404.

(3) If, during the inspection as required by paragraph (1) of this AD, a 

discrepancy is found on a TR slip ring, before next flight, replace it with a 

serviceable part in accordance with the instructions of AgustaWestland BT 

139-404.

Note 3: For the purpose of this AD, a serviceable part is a TR slip ring which is 

not affected by this AD – see Note 2 of this AD.

Condition for installation of a TR slip ring on a helicopter:

(4) From the effective date of this AD, installation of a TR slip ring is allowed, 

provided it is a serviceable part as defined in Note 3 of this AD.

Ref. Publications: AgustaWestland BT 139-404 original issue dated 22 December 2014.

The use of later approved revisions of this document 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. Based on the required actions and the compliance time, EASA have 

decided to issue a Final AD with Request for Comments, postponing the 

public consultation process until after publication.

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

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

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

this AD, please contact: AgustaWestland S.p.A. 

E-mail: aw139.mbx@agustawestland.com.