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 CAR 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/48 Honeywell Inertial Reference Unit 9/2002 Applicability: Honeywell inertial reference units (IRU) with part number (P/N) HG1075AB05, any serial number (last four digits) 0644 through 0723 (excluding 0652 and 0659), that incorporates Modification 3 but not Modification 7; or Honeywell IRU P/N HG1075GB05, with either serial number (last four digits) 0652 or 0659, that incorporates Modification 2 but not Modification 6. Note 1: These IRUs are primarily on early manufactured Dassault Falcon Jets, but could be incorporated on other aircraft through either an STC or CAR (1988) 35 modification Requirement: 1. Inspect any affected IRU for proper function in accordance with the instructions in Honeywell Alert Service Bulletin (ASB) HG1075AB-34-A0013, dated 21 May 2001; or Honeywell ASB HG1075GB-34-A0005, dated 21 May 2001, as applicable. 2. If, during the Requirement 1 inspection, the IRU does not function properly, remove the IRU from the aeroplane and return it to Honeywell for incorporation of Modification 6 or 7, as applicable. 3. If, during the Requirement 1 inspection, the IRU functions properly, remove the IRU from the aeroplane and return it to Honeywell for incorporation of Modification 6 or 7, as applicable. 4. IRUs identified in the applicability statement may not be installed in any aeroplane unless the IRU has been modified at Honeywell, Inc. and updated to one of the following: IRU P/N HG1075AB05 IRU, to Mod 7, or IRU P/N HG1075GB05 IRU, to Mod 6. Note 2: FAA AD 2002-13-07 Amdt 39-12795 refers. Compliance: For Requirement 1 - Within the ne xt 50 hours time in service (TIS) after the effective date of this Directive. For Requirement 2 - Prior to further flight after the Requirement 1 inspection. Instruments and Automatic Pilots AD/INST/48 (continued) For Requirement 3 - Within 200 hours TIS after the Requirement 1 inspection. For Requirement 4 - As of the effective date of this Directive. This Airworthiness Directive becomes effective on 5 September 2002. Background: This Directive requires the inspection of affected IRUs for proper function and the removal of the IRU either immediately or within 200 hours TIS, depending on the result of the inspection. The Directive is the result of a report that these IRUs may not function when using backup battery power in certain installations. Failure of an IRU to transition to backup battery power could result in loss of attitude, heading, together with position reference and could lead to the pilot making flight decisions that put the aircraft in unsafe flight conditions. Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority 29 July 2002 The above AD is notified in the Commonwealth of Australia Gazette on 14 August 2002.