EASA AD No.: 2013-0177

TE.CAP.00110-003 © European Aviation Safety Agency. All rights reserved. 1/2

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

EASA AIRWORTHINESS DIRECTIVE

AD No.: 2013-0177

Date: 08 August 2013

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 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):

AB139 and AW139 helicopters

TCDS Number: EASA.R.006

Foreign AD: Not applicable

Supersedure: None

ATA 29 Hydraulic Power – Flexible Hydraulic Hoses – Replacement

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

Philadelphia Corporation (formerly Agusta Aerospace Corporation)

Applicability: AB139 and AW139 helicopters, all serial numbers.

Reason: Occurrences of leaking hydraulic system flexible hoses have been reported 

on in-service helicopters.

The results of the subsequent technical investigation indicate that single 

braided flexible hydraulic hoses, which are part of the original AB/AW139 

design, may have insufficient strength to cope with hydraulic system pressure 

pulsations over a long period.

This condition, if not corrected, could lead to other occurrences of hydraulic 

system leaks, possibly resulting in loss of hydraulic power and consequent 

reduced control of the helicopter.

To address this potential unsafe condition, AgustaWestland introduced new 

flexible hydraulic hoses that are characterized by a “dual braided” design and 

published Bollettino Tecnico (BT) 139-307, providing instructions for 

replacement of all hydraulic flexible hoses in service.

For the reasons described above, this AD requires replacement of flexible 

hydraulic hoses with improved parts.

Effective Date: 22 August 2013
EASA AD No.: 2013-0177

TE.CAP.00110-003 © European Aviation Safety Agency. All rights reserved. 2/2

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

Required Action(s) 

and Compliance

Time(s):

Required as indicated, unless accomplished previously:

(1) For helicopters equipped with a flexible hydraulic hose having a Part 

Number (P/N) listed in Table 1 of this AD, within 300 flight hours or 6 

months, whichever occurs first after the effective date of this AD, replace 

each affected flexible hydraulic hose with an improved flexible hydraulic 

hose in accordance with the instructions of AgustaWestland BT 139-307.

Table 1 – Affected flexible hydraulic hoses P/N

A494AE2E00E0670X

A494AE3E00E0424X

A494AE3E00E0530X

A494AE3E00E0570X

A494AE3E00E0580X

A494AE3E00E0620X

A494AE3E00E0930X

A494AE6E14E0348X

A494AE6E21E0330X

(2) After modification of a helicopter as required by paragraph (1) of this AD, 

do not install a flexible hydraulic hose having a P/N listed in Table 1 of this 

AD on that helicopter.

(3) For a helicopter equipped only with flexible hydraulic hoses not having a 

P/N listed in Table 1 of this AD, from the effective date of this AD, do not 

install a flexible hydraulic hose having a P/N listed in Table 1 of this AD on 

that helicopter.

Ref. Publications: AgustaWestland BT 139-307 rev. / , dated 19 June 2013.

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, 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 AgustaWestland S.p.A.:

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