AD/B747/308 - Air Data System (Cth)

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.

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.