AD/A320/162 Amdt 1 Integrated Standby Instrument System (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/A320/162 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 A319, A320 and A321 Series Aeroplanes

AD/A320/162 Amdt 1 Integrated Standby Instrument System 2/2006

Applicability:	Airbus A318, A319, A320 and A321 aeroplanes, all serial numbers, fitted with Airbus Modification 27620 during production or Airbus Service Bulletin (SB) A320-34-1261 embodied whilst in service and that have not had modification 35536 installed during production or SB A320-34-1335 embodied whilst in service.
Requirement:	Perform a reset of Integrated Standby Instrument System (ISIS) according to the following procedure:
(i)    Open the NAV/STBY/HORIZON circuit breaker on the 49VU panel (5FN, location F12) for more than 5 seconds, then close it.
(ii)   After some seconds, the INIT page comes into view.
Caution:  Do not reset ISIS in flight.
A complete electrical shut down of the aircraft is also sufficient to reset ISIS and is an alternative means to the above procedure.
Note:  DGAC F-2004-168 R1 (EASA Approval 2005-6439) refers.
Compliance:	Remains unchanged as ‘Within three calendar days after the effective date of this Directive, but not exceeding five calendar days from the last ISIS reset or aeroplane complete power off, and thereafter at intervals not exceeding five calendar days’.
This Amendment becomes effective on 16 February 2006.
Background:	An A340 operator reported the loss of ISIS followed, during the same flight, by the loss of all Electronic Instrument System (EIS) Display Units (DU). A318, A319, A320 and A321 aeroplanes may be fitted with the same design. The failure mode of ISIS has been identified as a time counter fault after 145 hours of ISIS continuous power supply. AD/A320/157 Amdt 1 (DGAC AD F-2004-104 R1) mandates the operational procedure to recover lost EIS Display Units, pending a new EIS standard addressing the misbehavior.

Situations where EIS DUs and ISIS are simultaneously unavailable may result in hazardous consequences in certain phases of flight.  The original issue of this Directive required a periodic on ground-reset procedure to prevent the ISIS failure by clearing the time counter.  This Amendment continues that requirement but reduces the scope of the applicability.

The original issue of this Directive became effective on 25 October 2004.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

20 December 2005