AD/A330/53 Amdt 1 Electronic Instrument System Display Units (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/A330/53 and issues the following 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 Amdt 1 Electronic Instrument System Display Units 13/2005 DM

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) A330-31-3056 or A330-31-3057 whilst in service.
b.    Version L5 installed through either modification 51974 during production or Airbus SB A330-31-3056 or A330-31-3069 whilst in service.
Requirement:	Amend the Aircraft Flight Manual (AFM) to incorporate the following operational procedure, this may be accomplished by inserting a copy of this Directive or AFM Temporary Revision (TR) 4.03.00/26 in the AFM:
“At each flight crew change, switch OFF all displays units before completing Parking Check-list.”
Note 1:  As the flight crew will set all Display Units (DU) back ON during the next preliminary cockpit preparation, an electrical cut off of more than 5 seconds is thus ensured, preventing automatic reset of DUs.
Note 2:  Any later revision of the TRs approved by the European Aviation Safety Agency or any general AFM revision including this procedure is acceptable for compliance with this Directive.
Note 3:  This operational procedure has been published in Operations Engineering Bulletin (OEB) 59/1.
Note 4:  All Operator Telex (AOT) A330-31A3092 is cancelled.
Note 5:  DGAC AD F-2005-166R1 (EASA approval 2005-6378) refers.
Compliance:	Before 16 November 2005.
This Amendment becomes effective on 10 November 2005.

Background:

The Direction Générale de l’Aviation Civile of France (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.

The original issue of this Directive required the periodic ‘switching off’ procedure to be performed by flight crew in accordance with DGAC AD UF-2005-166 before each crew change.

This Amendment continues the ‘switching off’, but also requires the AFM to be amended.

The original issue of this Directive became effective on 28 September 2005.

James Coyne
Delegate of the Civil Aviation Safety Authority

2 November 2005