What was found
DUAL CADC FAILURE CAUSING FAILURE IN TRANSPONDER ALTITUDE REPORTING & INACCURATE ALTIMETER & AIRSPEED INDICATIONS. NR 1 & NR 3 INS WOULD NOT UPDATE. REMOVED AND REPLACED NR 1 CADC. CHECKED ALL DRAINS FOR MOISTURE; NONE FOUND. PURGED PITOT/STATIC LINES AND FITTINGS WITH DRY NITROGEN ON BOTH SYSTEMS. RERACKED NR 2 CADC. PERFORMED FULL PITOT STATIC CHECK FOR ALL ASSOCIATED AIR DATA INSTRUMENTS AND LEAKS IN THE SYSTEM. NO LEAKS NOTED.