As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING HEAVY CHECK, EPSU TEST YIELDS FAULT "335138 EPSU (10WL) FWD L". NOTE: THIS DID NOT CAUSE A FLIGHT DELAY. REMOVED AND REPLACED EMERGENCY POWER SUPPLY UNIT (EPSU) 10WL FOLLOWING AMM 33-51-38-000-001-A AND AMM 33-51-38-400-001-A. BITE TEST, INTERFACE AND POWER-UP TEST OKAY. NO FURTHER MAINTENANCE ACTION REQUIRED.