What was found
DURING TAXI OUT, THE OVERSPEED WARNING ACTIVATED AND THE PILOTS ALTIMETER AND ALTITUDE ALERTER FLAGGED. THE CREW ABORTED THE DEPARTURE AND RETURNED TO THE RAMP. THE ADC WAS FOUND TO BE DEFECTIVE AND WAS REPLACED ON 2/27/2006. THE SYSTEM WAS TESTED AND INSPECTED, FOUND TO COMPLY, AND THE AIRCRAFT REMAINS RVSM COMPLAINT. THE AIRCRAFT WAS RETURNED TO SERVICE ON 2/27/2006. THERE HAS BEEN ONE PRIOR REPORT OF A PROBLEM WITH THIS SYS ON 5/25/2005. (K)