Beechjet 400
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; Flight Crew Overcame Equipment Problem
Aircraft
While at our cruise altitude of FL380 (we filed for FL400); we were cleared to descend to FL340. Just as I began descending; I turned on the left; then right; engine anti-ice. About one second after turning the right engine anti-ice; the autopilot and yaw damp disconnected; and the pilot's Primary Flight Display (PFD) and Navigation Display (ND) went dark. I silenced the autopilot aural disconnect warning took control manually and continued descending. The Captain assessed the situation and reported the left avionics switch turned off and would not reset and remain on. The Air Data Computer (ADC) went out too and the FMS went into Dead Reckoning (DR) mode and remained there for the remained of the flight. About 5 minutes later; I turned the engine anti-ice off.Destination weather was 200 OVC and 1 mile; so the decision was made to divert to a VFR airport. About 8 minutes later; the Captain attempted to turn the left avionics switch on again; and was successful. It was decided to continue to the diversionary airport in case the problem reoccurred. The connection between engine anti-ice was not apparent. Avionics and autopilot capability was returned to normal except for the FMS which remained in DR. ATC provided vectors toward [alternate] airport. An ILS approach was made in green needles and landing was normal.
BE-400XP FO reported losing multiple systems after turning right engine anti-ice on.