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. Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes AD/CESSNA 170/74 KAP 140 Autopilot System 10/2004 Applicability: Cessna 172 R and 172S model aeroplanes listed below that are equipped with a Honeywell KAP 140 autopilot computer system, part number (P/N) 065-00176-2501, 065-00176-5001, 065-00176-5101 or 065-00176-5201, all serial numbers. Model 172R 172S Serial Numbers 17280001 through 17281073, 17281075 through 17281127 and 17281130 172S8001 through 172S9195, 172S9197, 172S9198 and 172S9200 through 172S9203 Note 1: The KAP 140 P/Ns listed above are in addition to those listed in AD/CESSNA 170/73 Requirement: 1. Install the update to the KC 140 autopilot computer system operating software by following Honeywell Installation Bulletin No. 491, Rev. 3, dated April 2003; Cessna Service Bulletin (SB) SB02-22-01, dated 25 November 2002 and Honeywell SB No. KC 140-M1, dated August 2002. 2. KC 140 autopilot computer systems P/Ns 065-00176-2501, 065-00176-5001, 065-00176-5101 or 065-00176-5201 may not be installed on any Cessna Model 172R or 172S aeroplanes as a replacement part unless the computer has been modified as specified in Requirements 1 of this Directive. Note 2: FAA AD 2004-15-18 Amdt 39-13752 refers. Compliance: For Requirement 1 - Within 100 hours time in service after the effective date of this Directive. For Requirement 2 - As of the effective date of this Directive. This Airworthiness Directive becomes effective on 30 September 2004. Background: The United States Federal Aviation Administration (FAA) has received reports of inadvertent and undetected engagement of the autopilot system in Cessna Models 172R, 172S, 182S, 182T, T182T, 206H, and T206H aeroplanes. These aeroplanes are equipped with a Honeywell KAP 140 autopilot computer system installed in the centre instrument control panel near the throttle. Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes AD/CESSNA 170/74 (continued) However, when issuing AD 2003-24-13 the FAA inadvertently omitted four part numbers from the applicability that was reflected in AD/CESSNA 170/73. This Directive, whilst not superseding AD/CESSNA 170/73, complements that Directive by listing the omitted KAP 140 autopilot computer system part numbers. This Directive requires the installation of an update to the operating software of the KAP 140 autopilot computer system. This action is intended to prevent unintentional engagement of the KAP 140 autopilot computer system, which could cause the pilot to take inappropriate actions. Gary J Carr Delegate of the Civil Aviation Safety Authority 13 August 2004 The above AD is notified in the Commonwealth of Australia Gazette on 8 September 2004.