What was found
FLT 309 - KDEN-KDAY - ON CLIMB-OUT AROUND FL27.0 CAPTAIN NOTICED HIGH TAS/MACH IN COMPARISON WITH THE FIRST OFFICER INSTRUMENTS. AIRSPEED WAS ABOUT 20 KNOTS APART AT THAT POINT CAPTAIN MACH .940, F/O''S .723, TAS 520 AT LEVEL OFF CONDITIONS BETWEEN THE CAPTAINS AND FIRST OFFICERS INSTRUMENTS REMAINED ABOUT THE SAME ON THE SPLIT. BOTH PILOTS ATTEMPTED ALTERNATE STATIC SOURCE WITH NO CORRECTION. RETURNED TO KGEN WITHOUT FURTHER INCIDENT. TROUBLESHOT TO A DEFECTIVE ADC IN THE NR 1 POSITION. REMOVED AND REPLACED NR 1 ADC. GROUND OPERATIONAL CHECKED NORMAL IAW B727 MM 34-12-0. RETURNED TO SERVICE. (M)