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 participate 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 accomplishing any applicable ADs. Consequently, no person 

may operate an aircraft to which an Airworthiness Directive applies, except in accordance with the requirements of that 

Airworthiness Directive 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]. 

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, A319-131, A319-132, A319-133, A320-

111, A320-211, A320-212, A320-214, A320-215, A320-216, A320-231, 

A320-232, A320-233, A321-111, A321-112, A321-131, A321-211, A321-

212, A321-213, A321-231 and A321-232 aeroplanes, all manufacturer 

serial numbers, except aeroplanes that 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 loss of the AC ESS BUS and DC ESS BUS 

and connected systems. The affected systems 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 during 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 the capability of the flight crew and 

could contribute to a loss of situational awareness and consequent control 
EASA 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 System in accordance with the 

instructions of Airbus Service Bulletin (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 & Research 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: AIRBUS – Airworthiness Office – EAS, 

Fax +33 5 61 93 44 51, E-mail: account.airworth-eas@airbus.com .