As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING MAINTENANCE BASE VISIT FOUND THE NR 1 EMERGENCY POWER SUPPLY UNIT TO BE INOPERABLE. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE NR 1 EMERGENCY POWER SUPPLY UNIT IAW 33-50-04-000-801 AND 33-50-04-400-801-A. THE AIRCRAFT WAS RETURNED TO SERVICE.