What was found
DURING PREFLIGHT FOUND FORWARD HALF OF AIRCRAFT EMERGENCY LIGHTS TO NOT WORK, INCLUDING IN THE FLIGHTDECK. ALSO GOT EMER LT BATT FAULT EICAS MESSAGE WHEN EMERGENCY LIGHT SWITCH IS ON. REMOVED FROM SERVICE. INTERROGATED CMC AND FOUND FAULT 33500001UT1: C/W FIM 33-50-00-810-801-A STEPS 1-8C . REMOVED ELPU FWD RT PER AMM 33-50-01, 2 MIGSIA INSTALLED. REPLACED FWD RIGHT ELPU REF AMM 33-50-01-400-801-A. REPLACED FWD RIGHT ELPU BATTERY REF AMM 33-50-01-400-802-A. OPS TEST GOOD. EMER LT BATT FAULT EICAS MESSAGE NO LONGER ACTIVE. RETURNED TO SERVICE.