What was found
FLT 440 - STL-PHX - EMERGENCY LIGHTS - EMERGENCY EXIT PATH LIGHTS AND WALL MOUNTED LIGHTS AT ROWS 8L, 8R, 10L, & 10R ARE INOPERATIVE. REMOVED AND REPLACED MID EMERGENCY POWER SUPPLY UNIT (EPSU) IAW MAINTENANCE MANUAL 33-51-38-401. OPERATIONAL CHECK WAS GOOD.