What was found
(CAN) AIRCRAFT WAS UNABLE TO TRANSMIT ON ANY OF THE 3 COMMS. MAINTENANCE DISCOVERED THE CONNECTOR TO BACK OF THE RADIO RACK LOOSE. THE CONNECTOR WAS CONNECTED, COMMS TESTED, AND THE AIRCRAFT RETURNED TO SERVICE. AVIONICS HAS ADVISED THAT THESE CONNECTORS CAN BE A PROBLEM, AS THE METHOD OF ATTACHMENT, AND THE MATERIAL OF THE CONNECTOR CAN CAUSE IT TO BREAK.