What was found
AIRSPEED UNRELIABLE GOING THROUGH FL200 DURING DESCENT. VARIOUS OTHER MALFUNCTIONS CAME AND WENT. LEVEL 2 ELEVATOR FEEL MALFUNCTION. IAS SPEED AND FLIGHT DIRECTORS CAME AND WENT. REMOVED AND REPLACED #1 ADC PER MD11 AMM CH 34-16-01. PERFORMED OPS TEST PER 34-16-01-700-801 AND 34-16-01-700-804 AND FCC1 AND FCC2 AUTOLAND RTS TEST PER 22-01-01-501. ALL TESTS PASSED. REMOVED AND REPLACED #2 FCC OUT OF PERCAUTION PER MD11 AMM CH 22-01-03. PERFORMED ATS RTS TEST PER 22-00-00-700-801. TEST PASSED. ALL WORK PERFORMED BY CAT CERTIFIED MECHANIC.