What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS WHILE ON DOWNWIND, ORD, CLEAN CONFIG, SPEED 250, LEVEL 7000 MSL. THE MLG WARNING HORN CAME ON ALONG WITH 3 RED LIGHTS IN GEAR HANDLES WARNING WENT AWAY APPROX 30 SEC LATER. MAINTENANCE ACCOMPLISHED BITE OF DFGCS, SMYDS, AND PROX BOX SHOWED NO PREVIOUS FLT LEG FAULTS. REPLACED AFT TWO (#1 SYSTEM) RADIO ALTIMETER ANTENNAS IAW AMM 34-33-11. #1 RA SYSTEM TESTED NORMALLY. PERFORMED RADIO ALTITUDE SIMULATION TEST IAW AMM 34-33-00 AND LANDING WARNING SYSTEM TEST IAW AMM 31-51-00. OPS CHECKS GOOD.