AD/B767/197 Amdt 2 Air Data System (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B767/197 Amdt 1 and issues the following AD under subregulation 39.1 (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.

Boeing 767 Series Aeroplanes

AD/B767/197 Amdt 2 Air Data System 2/2005

Applicability	Model 767-200, 767-300 and 767-300F series aeroplanes identified in Boeing Alert Service Bulletin (ASB) 767-34A0332, Revision 2, dated 30 September 2004.
Requirement:	1.    Either:
a.     Modify the air data switching system and do a system functional test, according to the Accomplishment Instructions of ASB 767-34A0332, Revision 1 dated 24 April 2003 or Revision 2.
or,
b.    Carry out the following:
(i)    Change the termination of the wires and perform an operational test, according to the Accomplishment Instructions of Boeing Special Attention SB 767-31-0149, Revision 1, dated 7 November 2002 and
(ii)   Modify the air data switching system and do a system functional test, according to the Accomplishment Instructions of SB 767-34A0332, Revision 1 or Revision 2.
Note 1:  Requirement 1 provides two alternate methods of compliance, if Requirement 1.b. is selected the compliance date for the modification of the air data switching system (ASB 767-34A0332 Revision 1 or Revision 2) is extended from 24 months to 72 months.
Modifications accomplished before the effective date of the original issue of this Directive in accordance with Boeing ASB 767-34A0332 dated 10 January 2002 are considered acceptable for compliance with Requirement 1.a.
Modifications accomplished in accordance with Requirement 2 of the original issue of this Directive are also considered acceptable for compliance with Requirement 1.a.

2.    For aeroplanes that are identified in ASB 767-34A0332, Revision 2 and also identified in any of the Boeing service bulletins listed below, unless previously accomplished, carry out all actions associated with replacing the existing Engine Indication and Crew Alerting System (EICAS) computers with improved EICAS computers, according to the Accomplishment Instructions of the applicable service bulletin specified below.  This includes performing an EICAS readout comparison to ensure that the applicable software is used; replacing the existing EICAS computers with new, improved EICAS computers that can be upgraded with certain software together with making related wiring changes.
767-31-0091 Revision 3 dated 27 April 2000 767-31-0098 Revision 2 dated 21 October 1999 767-31-0099 Revision 3 dated 8 February 2001 767-31-0100 Revision 2 dated 29 July 1999 767-31-0101 dated 6 July 2000
Note 2:  The Boeing service bulletins listed above all include Appendices A, B and C,
3.    Parts listed in the “Existing Part Number” column under paragraph 2.E. of the following Boeing SBs shall not be installed on any aeroplane as a replacement part:
767-31-0091 Rev 3 767-31-0098 Rev 2	767-31-0099 Rev 3 767-31-0100 Rev 2	767-31-0101 Original
Note 3:  FAA AD 2004-10-05 Amdt 39-13635 refers.
Compliance:	For Requirement 1.a. - Remains unchanged as ‘Within 24 months after the effective date of Amendment 1 to this Directive’.
For Requirement 1.b.(i) - Remains unchanged as ‘Within 18 months after the effective date of Amendment 1 to this Directive’.
For Requirement 1.b.(ii) - Remains unchanged as ‘Within 72 months after the effective date of Amendment 1 to this Directive’.
For Requirement 2 - Prior to, or concurrently with, SB 767-34A0332, Revision 1 or Revision 2.
For Requirement 3 - As of the effective date of the original issue of this Directive.
This Amendment becomes effective on 17 February 2005.

Background:	The original issue of this Directive required a modification of the ADC system, which involves installing certain new circuit breakers, relays, and related components, and making various wiring changes in and between the flight deck and main equipment centre.  For certain aeroplanes, this amendment also required accomplishment of various other actions prior to, or concurrently with, the modification of the ADC system.  For some aeroplanes, this Directive also contained an option that extended the compliance time to accomplish the modification of the ADC system.
These actions were considered necessary to ensure that the flight crew is able to silence an erroneous overspeed or stall aural warning.  A persistent erroneous warning could confuse and distract the flight crew and lead to an increase in the flight crews workload.  Such a situation could lead the flight crew to act on hazardously misleading information, which could result in loss of control of the aeroplane.
Amendment 1, whilst continuing the requirements of the original issue of the Directive, clarified the optional methods of complying with Requirement 1.
This Amendment introduces ASB 767-34A0332 Revision 2 as an alternate method of compliance and corrects a typographical error in Note 1.  The Amendment also changes applicability of the Directive by the deletion of four aeroplanes and the inclusion of two additional aeroplanes.
Amendment 1 of this Airworthiness Directive became effective on 30 September 2004.
The original issue of this Airworthiness Directive became effective on 5 August 2004.

James Coyne
Delegate of the Civil Aviation Safety Authority

23 December 2004

The above AD is notified in the Commonwealth of Australia Gazette on 26 January 2005.