EASA AD No.: 2009-0042

EASA Form 110 Page 1/2 

## EASA AIRWORTHINESS DIRECTIVE

AD No.: 2009-0042

Date: 25 February 2009

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 participat e in the 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 ensured by a ccomplishing any applicable ADs. Consequently, no person may opera te an aircraft to which an AD applies, except in accordance with the requirements of that AD unless otherwise specified by the Age ncy [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) exemptio n]. 

### Type Approval Holder’s Name : Agusta S.p.A. Type/Model designation(s) :
AB139 and AW139 helicopters

TCDS Number : EASA.R.006

Foreign AD : Not applicable

Supersedure : None



### ATA 24 Electrical Power – Generator Control Unit (GCU) - Replacement

Manufacturer(s): Agusta S.p.A.
Applicability: All AB139 and AW139 helicopters, all serial numbers except from S/N 31002 to S/N 31004 and S/N 31007

. Reason: Laboratory tests performed on a new GCU model under development have shown a potential fault in the overvoltag e protection of the currently installed generator control units P/N 1152550-3. This condition, if not corrected, could adversely affect the electrical po wer generation and distribution system functionalities. Therefore, this AD requires the replacement of the affected units with improved GCU to prevent the in serv ice occurrence of the above described unsafe condition.

Effective Date: 11 March 2009

Required action(s) and Compliance Time(s): Required as indicated, unless accomplished previously: (1) Within 6 months after the effective date of this AD remove the number 1 and 2 GCU P/N 1152550-3 and replace with number 1 and 2 GCU P/N 1152550-5 or, as an alternative, with two generator control units P/N 1152550-4, in accordance with the instructions of Agusta Bollettino Tecnico 139-133. (2) The two installed generator cont rol units must have the same P/N (1152550-4 or 1152550-5).EASA AD No.: 2009-0042

EASA Form 110 Page 2/2 (3) After the effective date of this AD, no person shall install a GCU P/N 1152550-3 on an helicopter.

Ref. Publications: Agusta Bollettino Tecnico 139-133 original issue dated 20 February 2009. The use of later approved revision 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. The required actions and the risk a llowance 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 to the Airworthiness Directives, Safety Management & Re search Section, Certification Directorate, EASA. E-mail: ADs@easa.europa.eu

. 4. For any question concerning the tec hnical content of the requirements in this AD, please contact Agusta S.p.A. E-mail: aw139.mbx@agustawestland.com

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