As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOSS OF NR 1 VHF NAV OCCURRED ON APPROACH INTO BIS. CIRCUIT BREAKER POPPED AND WOULD NOT RESET. FLIGHT RETURNED TO MSP AND LANDED WITHOUT INCIDENT. REPLACED RADIO NAV SWITCHING UNIT AND BOTH NR 1 AND NR 2 NAV RECEIVERS. OPERATIONAL CHECK OK. AIRCRAFT RETURNED TO SERVICE.