What was found
ACFT WAS NOT OUT OF SERVICE DUE TO THIS EVENT REFERENCE LP275823 ITEM NR 1, DURING HEAVY CHECK EPSU BATTERY 11WL EXIT L, FAILED TEST. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED EPSU BATTERY 11WL, EXIT L IAW AMM 33-51-38-000-002-A/400-002-A. OPS TEST GOOD.