What was found
IN APPROACH PHASE, GEAR SELECTED DOWN, WE REC'VD TWO GREEN AND ONE RED AND A SINGLE WARNING MESSAGE "GEAR DISAGREE". THE RED INDICATION WAS FOR THE RIGHT MAIN LANDING GEAR. WARNING MESSAGE OCCURRED ABOUT 7 SECS AFTER SELECTING GEAR DOWN. HY TEMPS AND PSI WERE ALL IN THE GREEN. C/W QRH. ATTEMPTED TO EXTENDED GEAR FOUR TIMES. GEAR DISAGREE EACH TIME WITH RT MLG SHOWING RED. USED EMERGENCY GEAR EXTENSION TO GET GEAR DOWN AND LOCKED. ****AIRCRAFT REMOVED FROM SERVICE **** C/W M ACTION FOR MEL 32-30-01 REF 337259/1 FOR MEL. R&R RH MLG SIDE STAY ACTUATOR ALL WORK DONE IAW AMM 32-32-01-04 LEAK AND OPS CHECK GOOD REMOVED PLACARD AND REMOVED FROM MEL.