What was found
DURING HEAVY MAINTENANCE: FAULT EPSU-EMERGENCY POWER SUPPLY UNIT 14WL MESSAGE IN OPERATIONAL EME RGENCY LIGHT TEST IN PASSENGER CABIN; PERFORMED FAULT CONFIRMATION IAW TSM 33-51-00-810-822-A. REMOVED AND REPLACED EPSU (14WL) IAW AMM 33-51-38-000-001-A AND AMM 23-51-38-400-001-A. REMOVED AND REPLACED BATTERY EPSU (14WL) IAW AMM 33-51-38-000-002-A AND AMM 33-51-38-400-002-A. PERFORMED OPERATIONAL TEST EPSU IAW AMM 33-51-00-710-001-A. PERFORMED INTERFACE AND POWER-UP TEST OF THE CABIN INTERCOMMUNICATION DATA SYSTEM IAW AMM 23-73-00-740-005-B. THE TESTS ARE OK.