What was found
PDIS 786 34-14 4200 17MAY20 TYS FACT U LOGPAGES:3215525 REJECTED ON RUNWAY DUE TO NO AIRSPEED ON PILOT/LEFT SIDE. REJECTED AT 78 KTS FACT 17MAY20 12:59 TYS U REPLACED LH CADC AS PER 757 MM 34-12-01-4 AIR DATA COMPUTER - REMOVAL/INSTALLATION EFFECT: 087,770-799,901-910,912-928,930,933-944,946-979,985- 999 INSPECTED ALL PITOT PROBES. FOUND CLEAR. WHEN ATTEMPTING TEST OF ADC , FOUND WHEN HOLDING TEST SWITCH UP, SYSTEM WENT TO HARD FAULT. AFTER REPLACEMENT OF ADC EVERYTHING WORKS OK.