COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Radio Communication and Navigation Equipment AD/RAD/59 Centaurus Ground Proximity Warning System 4/97 Applicability: All Centaurus C3-100 Ground Proximity Warning Systems (GPWS) manufactured by Airtell International, Inc, fitted to aircraft as a mandatory requirement. Note: This equipment known to be fitted to, but not limited to, the following aircraft types and models: Beech 99 series, Beech 200 Series, Dassault Aviation Model Mystere-Falcon 200 Series, Embraer (Empresa Brasileria de Aeronautica S.A.) EMB-110 series, Fairchild Aircraft Model SA226-TC series Fairchild Aircraft Model SA227-AT series Grumman Model G-73 Mallard. Requirement: Remove the C3-100 GPWS from service and replace with similar type of equipment which meets the minimum performance standards specified in United States Federal Aviation Administration Technical Standard Order C-92b dated 19 August 1976. Note: FAA AD 97-01-12 Amdt 39-9883 refers. Compliance: Remove from service before 26 May 1997. This Airworthiness Directive becomes effective on 27 March 1997. Background: The results of a FAA investigation revealed that, under certain circumstances, the Centaurus GPWS does not provide the flight crew with aural warnings to indicate that the aircraft is descending. The actions mandated by this Airworthiness Directive are intended to prevent the failure of the GPWS equipment providing those aural warnings to the flight crew. The absence of these warnings may inhibit the flight crew's ability to avoid controlled flight into terrain.