What was found
AIRCRAFT RETURNED TO EZE DUE TO RADAR PROBLEMS. *S/D* THE WEATHER RADAR RECEIVER/TRANSMITTER AND ANTENNA DRIVE UNIT WERE REPLACED AND THE SYSTEM OPERATION RETURNED TO NORMAL. SHOP CHECKOUT OF THE REMOVED UNITS FOUND THAT THERE WERE NO FAULTS WITH THE RECEIVER TRANSMITTER BUT THE ANTENNA DRIVE UNIT (P/N 622-5125-001), WAS FOUND TO HAVE THE AZIMUTH FAILED AND LOCKED AND THEREFORE WAS THE CAUSE OF THE RADAR SYSTEM FAILURE ON AIRCRAFT 6651.