As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DISCREPANCY: REFERENCE LP520272 #1 EPSU BATTERY (17WL) FAILED EPSU SYS TEST. AC WAS NOT GROUNDED AS A RESULT OF THE SDR REPORTABLE EVENT IT WAS A SCHEDULED RON HEAVY CHECK. CORRECTIVE ACTION: REMOVED AND REPLACED EPSU BATTERY (17WL) IAW AMM 33-51-38-000/400-002-A. OPS CHECK GOOD. AC OK FOR SERVICE. /END/.