Airworthiness Directives; Airtell International, Inc., Centaurus Model C3-100 Ground Proximity Warning System (GPWS), as Installed in Various Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Airtell International, Inc., Centaurus Model C3-100 GPWS equipment that is installed on any type of airplane, that requires replacement of this equipment with a similar type of equipment that meets specific performance requirements. This amendment is prompted by results of an investigation, which revealed that, under certain circumstances, the Centaurus GPWS equipment does not provide the flight crew with aural warnings to indicate that the airplane is descending. The actions specified by this AD are intended to prevent failure of the GPWS equipment to provide such aural warnings. If the flight crew relies on receiving such warnings and the GPWS equipment fails to provide those warnings, the ability of the flight crew to prevent the airplane from impacting the ground may be inhibited.