As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ONE-HALF OF SPLIT AVIONICS MASTER BUS SWITCH FAILED. DEFECTIVE HALF OF SWITCH WILL NOT TURN OFF LEAVING SOME AVIONICS SYSTEMS POWER CONTROLLED BY A/C MASTER SWITCH. SWITCH FAILED UNDER NORMAL OPERATING PARAMETERS. POSSIBLE CAUSE OF FAILURE IS DUE TO POOR SWITCH DESIGN AND SUBMITTER STATED NEEDS TO BE RE-DESIGNED. (X)