As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN FLT RADIO COMMUNICATION FAILURE (VHF NR 1 AND NR 2). AC AIR TURN BACK. MAINTENANCE CHECK FOUND RT CONTROL COLUMN PTT SW FUNCTION NO T GOOD. CAUSED RADIO SYSTEM FAILURE. IAW AMM23-51-07 REPLACED RT CONTROL COLUMN PTT SW AND OPERATIOAL TEST SYSTEM BACK, NORMAL.