As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VOLTAGE REGULATOR WAS INSTALLED, AIRCREW SQUAWKED LOW VOLTAGE WARNNG LIGHT REMAINED ON AT ALL POWER SETTINGS. TROUBLESHOOTING DETERMINED OUTPUT VOLTAGE WAS BELOW MINIMUM OUTPUT AND ERRATIC. VISUAL INSPECTION OF THE REGULATOR INDICATED NO SIGNS OF EXTERIOR DEFECTOR DAMANAGE. NO DISASSEMBLY WAS ATTEMPTED.