AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/INST/49 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. Instruments and Automatic Pilots AD/INST/49 Amdt 1 Rockwell Collins Air Data Computers 6/2003 Applicability: All Rockwell Collins air data computers (ADC) listed below; except ADC-85A computers part number 822-0370-113 or -123 with Rockwell Collins Service Bulletin (SB) 58 incorporated and installed on Saab 340 series aeroplanes. Unit Part Number Serial Number ADC-85 622-8051-002 All units (Incorporating Rockwell Collins 622-8051-003 Service Bulletin (SB) 58) ADC-85A 822-0370-113 All units (Incorporating SB 58) 822-0370-123 822-0370-139 822-0370-404 822-0370-408 ADC-850D 822-0389-133 All up to and including (Incorporating SB 58) 3DGW (except for 1P6D, 22RC-22RF and 23WK- 3DGP) ADC-850F 822-1036-406 All Units 822-1036-418 Note 1: These ADCs may be installed on, but not limited to, the following aeroplanes: Unit Aeroplane Model ADC-85/ADC-85A ADC-850D ADC-850F Astra AIA Chinese Y7 and Y8 Czech LET-610 DC-8 Falcon 20F Piaggio P-180 Raytheon B200, B300, C90A and 1900D Lear 60 Falcon 20, 50 and 50EX Requirement: 1. Unless already accomplished, carry out the following actions in accordance with Rockwell Collins SB 62, (ADC-85/85A/850C/850D/850E/850F-34-62), Revision No. 2, dated 7 March 2000, or SB 62, dated 25 October 1999, as applicable, together with the applicable Collins Computer Component Maintenance Manual and Collins Avionics Standard Shop Practices Instruction Manual: 1. Remove any affected ADC from the aeroplane. b. As applicable, replace or reprogram parts or circuit card assemblies on central processing unit (CPU) circuit cards. c. Test the ADC. 2. Affected ADCs may not be installed on any aeroplane, except Saab 340 series aeroplanes, unless the modification and test required by Requirement 1.b. and c. have been accomplished. Note 2: Rockwell Collins Operator Bulletin 99-7, dated August 1999, contains information about an operational placard to install until accomplishment of the actions of this Directive. While not necessary to address the unsafe condition in this Directive, CASA highly recommends that the placard be installed. Note 3: FAA AD 2002-14-19 Amdt 39-12819 and FAA Special Airworthiness Information Bulletin CE-03-21 refer. Compliance: For Requirement 1 - Remains unchanged as 'Within 12 months after the effective date of the original issue of this Directive'. For Requirement 2 - As of the effective date of this Amendment. This Amendment becomes effective on 12 June 2003. Background: The original issue of this Directive required replacement of any affected ADC with one that has a reprogrammed and tested CPU circuit card and circuit card assembly. The Directive was issued following a flight test that showed that these ADCs could display an unwarranted ADC flag in response to the aeroplane's "Normal/Alternate Air" static source selection capability. This could cause the flight crew to react to this incorrect flight information and possibly result in an unsafe operating condition. This Amendment is issued following advice from the United States Federal Aviation Administration that Saab 340 series aeroplanes were not affected. The original issue of this Directive became effective on 5 September 2002. Jim Coyne Delegate of the Civil Aviation Safety Authority 1 May 2003 The above AD is notified in the Commonwealth of Australia Gazette on 21 May 2003.