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. AMD Falcon 50 and 900 Series Aeroplanes AD/AMD 50/32 GPIRS Hybrid Data 1/2004 DM Applicability: Falcon 900EX aeroplanes fitted with Global Positioning/Inertial Reference System (GPIRS) part number (P/N) HG2001-GC03 or P/N HG2001-GD03, except aeroplanes with Dassault Aviation Service Bulletin (SB) F900EX-181 incorporated or modification M3386 embodied. Mystère-Falcon 900 aeroplanes fitted with GPIRS P/N HG 2001-GC03 or P/N HG2001- GD03, except aeroplanes with Dassault Aviation SB F900-318 incorporated or modification M3386 embodied. Mystère-Falcon 50 aeroplanes fitted with GPIRS P/N HG2001-GC02 or P/N HG2001-GC03 or P/N HG2001-GD03, except aeroplanes with Dassault Aviation SB F50-416 incorporated or modification M2873 embodied. Requirement: 1. Remove the Aircraft Flight Manual (AFM) temporary changes (TC) mandated by AD/AMD 50/27 and insert new TCs as follows: Aeroplane Model Remove Insert F900 TC 12 TC 15 F900EX TC 53 TC 57 F50 TC 58 TC 61 2. If the option of deactivating the GPS system by pulling and securing the circuit breakers have been implemented, incorporate Dassault Aviation SB F900EX- 190, F900-324 or F50-424, as applicable. Note 1: The incorporation of SB F900EX-190, F900-324 or F50-424, as applicable includes the cancellation of TC 15, TC 57 and TC 61, as applicable. 3. De-hybridise the GPIRS in accordance with Dassault Aviation SB F900EX-181 or F900-318, as applicable. Note 2: DGAC AD 2003-409(B) refers. Compliance: For Requirement 1 and 2 - Before further flight after the effective date of this Directive. AMD Falcon 50 and 900 Series Aeroplanes AD/AMD 50/32 (continued) For Requirement 3 - Within 25 months after the effective date of this Directive. This Airworthiness Directive becomes effective on 26 November 2003. Background: There is a potential for degraded GPS signals when the satellite constellation is not in an optimal position in relation to the aircraft. This anomaly can remain undetected by the GPIRS and can result in incorrect hybrid parameters being computed by the GPIRS. This Directive initially requires either the amendment of the AFM or deactivation of the GPS followed and the de-hybridisation of the GPIRS. This Directive replaces AD/AMD 50/27 which will be cancelled by issue 1/2004. David Villiers Delegate of the Civil Aviation Safety Authority 20 November 2003 The above AD is notified in the Commonwealth of Australia Gazette on 26 November 2003.