As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TURNBACK INSPECTION NOTED EMERGENCY LIGHT POWER SUPPLY 22LN VOLTAGE TO BE LOW. MAINTENANCE REMOVED AND REPLACED BATTERY PAC ON EMERGENCY LIGHTING POWER SUPPLY 22LN WITH A SERVICEABLE BATTERY PACK IAW SF3 AMM 33-50-10. OPS CHECKS GOOD AT THIS TIME. P/N 61-0478-9, S/N OFF 076A, P/N ON 6100478-9, S/N ON 9801228.