EASA AD No.: 2009-0235

EASA Form 110 Page 1/2 

## EASA AIRWORTHINESS DIRECTIVE

AD No.: 2009 - 0235

Date: 29 October 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 partic ipate 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 ens ured by accomplishing any applicable ADs. Consequently, no person may operate an aircraft to which an Airworthiness Directive app lies, except in accordance with the requirements of that Airworthiness Directive unless otherwise specified by the Ag ency [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]. 

### Type Approval Holder’s Name :
AIRBUS Type/Model designation(s) :
A318, A319, A320 and A321 aeroplanes

TCDS Number : EASA.A.064

Foreign AD : Not applicable

Supersedure : None



### ATA 24 Electrical Power – AC and DC ESS BUS Power Supply - Modification

Manufacturer(s): Airbus (formerly Airbus Industrie)

Applicability: Airbus A318-111, A318-112 , A318-121, A318-122, A319-111, A319-112, A319-113, A319-114, A319-115, A3 19-131, A319-132, A319-133, A320- 111, A320-211, A320-212, A320-214, A320-215, A320-216, A320-231, A320-232, A320-233, A321-111, A3 21-112, A321-131, A321-211, A321- 212, A321-213, A321-231 and A321-232 aeroplanes, all manufacturer serial numbers, except aeroplanes t hat have received Airbus modification (MOD) 37317 in production.
Reason: Several occurrences of loss of the AC BUS 1 have been reported which led in some instances to the lo ss of the AC ESS BUS and DC ESS BUS and connected systems. The affected sys tems include multiple flight deck Display Units (Primary Flight Display, Navigation Display and Upper Electronic Centralised Aircraft Monitoring display).
The reasons for these events have been investigated but have not been fully established for all cases. Due to the range of system losses some crews reported difficulty in establishing the failure cause duri ng the events and, consequently, the appropriate actions to be taken may not be completed in a timely manner. The loss of multiple display units, if not corrected expediently during a high workload period, potentially affects t he capability of the flight crew and could contribute to a loss of situat ional awareness and consequent controlEASA AD No.: 2009-0235

EASA Form 110 Page 2/2 of the aeroplane, which would constitute an unsafe condition.
This AD therefore mandates the modification of the electrical network configuration management logic consisting in adding an automatic switching of the AC and DC ESS BUS power supply such that upon the loss of the AC BUS 1, the AC BUS 2 will automatically take over the power supply. On pre-MOD aeroplanes , this power supply switching can only be accomplished manually from the cockpit and is covered by an Electronic Centralized Aircraft Monitoring (ECAM) procedure.

Effective Date: 12 November 2009

Required action(s) and Compliance Time(s): Required as indicated, unless accomplished previously: (1) Within 48 months after the effective date of this AD, modify the Electrical Power Distribution Sy stem in accordance with the instructions of Airbus Service Bu lletin (SB) A320-24-1120 Revision 3. (2) For aeroplanes previously modified in accordance with SB A320-24-1120 at any previous revision , no further action is required by this AD.

Ref. Publications: Airbus Service Bulletin A320-24-1120 Revision 3 dated 10 July 2009. 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. This AD was posted on 29 June 2009 as PAD 09-086 for consultation until 29 July 2009. The Comment Response Document can be found at http://ad.easa.europa.eu

. 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 te chnical content of the requirements in this AD, please contact: AIRBUS – Airworthiness Office – EAS, Fax +33 5 61 93 44 51, E-mail: account.airworth-eas@airbus.com

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