As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHILE MAINTENANCE WERE CARRYING OUT SOME TESTING IT WAS DISCOVERED THAT THE RT PUSH TO TALK SWITCH WAS UNSERVICEABLE, THIS SWITCH HAD BEEN REPLACED 22.7 HRS PREVIOUSLY. WHILE CHECKING THE HISTORY OF THESE SWITCH REPLACEMENTS, IT WAS DISCOVERED THAT WE HAVE HAD MULTIPLE FAILURES OF THIS SWITCH ON BOTH THE PILOT AND CO-PILOT SIDES.