What was found
CREW PERFORMED ALL PREFLIGHT FUNCTIONAL CHECKS OF ALL ACFT SYS. AT THAT TIME THE SPEED BRAKE/SPOILERON SYS WAS REPORTED BY CREW TO TEST NORMALLY. PAX LOADED AND CREW PREPARED FOR DEPARTURE. ON TAKEOFF ROLL "AIRSPEED WAS ALIVE". AT APPROX 80 KTS INDICATED AIRSPEED, MASTER CAUTION LIGHT ILLUMINATED AND FLASHING. VERIFIED THE "SPOILER" RED ANNUCIATOR WAS ILLUMINATED. IMMEDIATELY ABORTED TAKEOFF AND RETURNED WITH NO OTHER INCIDENT. TROUBLESHOT SYS, DETERMINED FAULT TO BE RT SPEED BRAKE/SPOILER DOWN & LOCKED POSITION INDICATOR SWITCH. REPAIRED IAW MM 27-60-07.