What was found
AIRCRAFT WAS GROUNDED: DURING CRUISE MULTIPLE ENGINE #1 STATUS MESSAGES DISPLAYED. Ï¿½ENGINE REVERSER LEFT; HYDRAULIC VALVE SUPPLY PRIMARY PUMP LEFT; HYDRAULIC VALVE AUTO BLEED RESERVOIR LEFT; DETECTOR FIRE 2A, 3A, 4A, ENGINE LEFT.Ï¿½ FLIGHT DECLARED AN EMERGENCY, RETURNED TO DFW, LANDING SAFELY. REPLACED ENGINE #1 MAIN ENGINE DATA CONCENTRATOR (MEDC) PER AMM 26-10-01. MESSAGES CLEARED. ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK.