What was found
ALTITUDE ALERT ON CONTINUOSLY IN LEVEL FLT. ALTITUDE NEVER OFF BY 50FT AND LIGHT & HORN ACTIVATED & HAD TO BE MANUALLY CORRECTED TO ALTITUDE WITH EITHER AUTOPILOT ON. USED NR 2 REMAINDER OF FLT DUE TO LOSS OF CAPT FD/ADC. REPLACED CAPT'S, F/O'S & STANDBY PITOT PROBES IAW MM34-11-15-04. R & R NR 1 & 2 FLT AUG COMPUTERS IAW MM 22-26-34-04. R & R NR 1 & 2 FEEL LIMIT COMPUTERS IAW AMM 27-23-26-04, OPS CHECKED NORMAL. PERFORMED HEATING TEST IAW AMM 34-11-15-04, 34-10-00-03. PERFORMED INSPECTION OF WATER TRAPS IAW AMM 12-24-34-00, NO CONTAMINATION FOUND. PERFORMED PITOT SYS LEAK DOWN TEST IAW MM 4-10-00-05, TESTED GOOD. NO ABNORMAL OR ERRATIC INDICATIONS DURING TESTING.