As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED VOR AND FD’S (FLIGHT DIRECTOR) BOTH FLASHING, TURNING RED AND DISAPPEARING FROM DISPLAYS. MULTIPLE VOR’S AND NAV SOURCES WERE TRIED, WITH NO CHANGE. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT, REMOVED AND REPLACED NUMBER 2 NAV RECEIVER AND PERFORMED CHECKS USING AIRCRAFT MAINTENANCE MANUAL. AIRCRAFT RELEASED FOR SERVICE.