COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F27 Series Aeroplanes 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 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. AD/F27/149 Fuel Differential Pressure Switches 3/2000 TX Applicability: Model F27 Mk 100 through Mk 700 series aeroplanes, all serial numbers. Requirement: 1. Inspect the installed fuel differential pressure switches and attaching fuel pressure sensing lines for proper installation in accordance with Fokker Service Bulletin (SB) F27/28-63 dated November 21, 1999. 2. Re-install, in accordance with Fokker SB F27/28-63 dated November 21,1999, any fuel differential pressure switches and/or fuel pressure sensing lines found incorrectly installed during the above inspection. Note: RLD AD (BLA) 1999-154 dated November 30, 1999 refers. Compliance: 1. Within one calendar month after the effective date of this directive. 2. Before further flight. This Airworthiness Directive becomes effective on 2 February 2000. Background: Recent instances have occurred where the fuel differential switch was installed upside down which can result in inadvertent cross-connection of the fuel pressure sensing lines inhibiting the function of the fuel filter icing warning system. This could leave an ice-blocked fuel filter undetected, leading to fuel starvation and engine flame-out. Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority 29 January 2000 The above AD is notified in the Commonwealth of Australia Gazette on 2 February 2000.