As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON A LOCAL TRAINING FLIGHT, ADVISED TOWER THEY WERE INBOUND WITH A RADIO FAILURE. ACFT WAS INSPECTED BY MAINTENANCE. NAV/COMM UNIT WAS REMOVED & THE CONNECTIONS WERE CLEANED. SYSTEM WAS FUNCTION TESTED SERVICEABLE IAW MANUFACTURER`S INSTRUCTIONS AND THE ACFT WAS RETURNED TO SERVICE.