What was found
MDPC/KMIA - ON FAE - FLT 800 - ON APPROACH, RIGHT MLG FAILED TO EXTEND. CREW ACCOMPLISHED MANUAL EXTENSION. ON GROUND, MAINTENANCE FOUND RIGHT MLG DOOR OUT OF RIG CAUSED BY A LOOSE MLG INBD FITTING. FITTING WAS TIGHTENED, DOOR WAS RIGGE D AND GEAR SWING ACCOMPLISHED PER 32-32-00. AIRCRAFT RETURNED TO SERVICE.