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 39.001(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. Dornier 328 Series Aeroplanes AD/DO 328/8 Proximity Switch Electrical Unit 1/2006 Applicability: Model 328-100 aeroplanes all serial numbers equipped with a landing gear proximity switch electrical unit (PSEU) part number (P/N) 8-700-03 or 8-700-04 installed. Requirement: If not previously accomplished, remove PSEUs P/N 8-700-03 or 8-700-04 and install a new PSEU P/N 8-700-04 Mod A in accordance with the Accomplishment Instructions of Dornier Service Bulletins SB-328-32-248 Revision 1 dated 22 April 1998. Note 1: For operators removing a P/N 8-700-03 unit, Dornier SB-328-32-143 must be performed prior to installation of a new unit. Note 2: A new PSEU P/N 8-700-05 may be installed as an alternate to the installation of a PSEU P/N 8-700-04 Mod A. Note 3: LBA AD 1998-137/2 refers. Compliance: Within 30 days after the effective date of this Directive. This Airworthiness Directive becomes effective on 19 January 2006. Background: The German Luftfahrt-Bundesamt (LBA) has received reports of intermittent shutoff of control circuits within the PSEU preventing, in some instances, normal extension of the landing gear. Investigations have determined the cause to be a manufacturing fault within the PSEU. This Directive requires the replacement of the faulty PSEUs. James Coyne Delegate of the Civil Aviation Safety Authority 29 November 2005