Ad/A330/53 - Electronic Instrument System Display Units (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Airbus Industrie A330 Series Aeroplanes

AD/A330/53 Electronic Instrument System Display Units 12/2005 TX

Applicability:

Airbus A330 aeroplanes, all certified models, all serial numbers, equipped with Electronic Instrument System EIS 2 software versions as follows:

a.     Version L4-1 installed through either modification 51153 during production or Airbus Service Bulletin (SB) A330-31-3057 or A330-31-3056 whilst in service.

b.    Version L5 installed through either modification 51974 during production or Airbus SB A330-31-3069 or A330-31-3056 whilst in service.

Requirement:

Action in accordance with Direction Générale de l’Aviation Civile of France (DGAC) Emergency AD UF-2005-166 (EASA Approval 2005-6343).

Note:  Airbus A330 Operational Engineering Bulletin (OEB) 59/1 refers.

Compliance:

Within twenty four hours after the effective date of this Directive

This Airworthiness Directive becomes effective on 28 September 2005.

Background:

The DGAC has advised that an operator reported the simultaneous blanking of three EIS DUs on an A330 aircraft during flight.  These DUs went blank and displayed the message “INVALID DISPLAY UNIT”.  The DU’s were recovered automatically after approximately 40 seconds and the flight was continued normally.

The analysis of Display Management Computer (DMC) data confirmed the three DUs had undergone a simultaneous automatic reset followed by a power on self-test.  The investigation shows that after a continuous power on of a DU for more than six days, an internal timer reaches a limit that provokes an automatic reset.

A situation where both the EIS DUs and standby instruments are simultaneously unavailable may have unsafe consequences in certain phases of flight.

AD/A330/52 previously required a ‘switching off/switching on’ procedure of the EIS to be performed every four days whilst the aircraft was on the ground  This Directive requires the periodic ‘switching off’ procedure to be performed by flight crew before each crew change.  This procedure will reinitialise the internal timer of all the DUs.

This Directive supersedes AD/A330/52 which has been cancelled.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 September 2005