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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 39.1 (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.

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Boeing 747 Series Aeroplanes

AD/B747/308 Air Data System 8/2004

Applicability: Model 747-400, 747-400D and 747-400F series aeroplanes identified in Boeing Alert Service Bulletin (ASB) 747-34A2460, Revision 2, dated 14 June 2001.

Requirement: 1. Change the termination of the wires and perform an operational test, according to the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-31-2313, Revision 1, dated 26 September 2002; and/or

Note 1: Requirement 1 is optional for all aeroplanes without three Air Data Computers (ADC) and, if accomplished, extends the compliance for Requirement 2 from 24 months to 72 months.

2. Modify the ADC system as follows:

Re-route wires associated with ADC overspeed warnings, replace the P1-1 and P3-1 module assemblies in the flight deck with improved module assemblies, install various wires in and between the flight deck and main equipment centre of the aeroplane, and perform a test of the source select module and a system functional test, according to the Accomplishment Instructions of ASB 747- 34A2460, Revision 2.

Note 2: Boeing SB 747-34A2460, Revision 2, refers to Boeing Component Service Bulletins 233U2200-31-01 and 233U2205- 31-01, both dated 20 April 1995, as additional sources for instructions to change the ADC computer source select switch on the P1-1 and P3-1 panels, respectively.

3. Unless previously accomplished, carry out the following:

For aeroplanes listed in Boeing SB

747-31-2179, dated

26 May 1994

747-31-2180, dated

17 March 1994

747-31-2217, dated

19 May 1994

747-31-2217 and

747-31-2178, dated

1 July 1993

747-31-2217 and

747-45-2005, dated

8 February 1990

747-31-2217 and

747-45-2010, dated

17 December 1992

747-31-2217 and

747-31-2163, dated

14 February 1991

Accomplish all actions associated with:

Replacing the three Electronic Flight Information System (EFIS)/Engine Indicating and Crew Alerting System (EICAS) interface units (EIU) in the main equipment centre with improved EIUs and installing new software in six integrated display units (IDU) and three EIUs.

Replacing the three EIUs in the main equipment centre with improved EIUs and installing new software in six IDUs and three EIUs.

Installing new software in six IDUs and three EIUs.

Replacing three EIUs with improved EIUs and installing new software in six IDUs and three EIUs.

Replacing certain central maintenance computers (CMCs) with improved CMCs, modifying related wiring, and modifying the data loader control panel.

Installing new software in the CMC.

Installing new software in six IDUs and three EIUs.

According to the Accomplishment Instructions of Boeing SB

747-31-2179

747-31-2180

747-31-2217

747-31-2178

747-45-2005

747-45-2010

747-31-2163