What was found
WHEN SELECTING AVIONICS ON, WE HEARD A NOISE LIKE A FAN BLADES HITTING SOMETHING, THEN WE SMELLED THE ODOR OF SOMETHING BURNING. TURNED AVIONICS BACK OFF AND WHEN TURNING ON AVIONICS BACK ON AGAIN WE RECEIVED "MAU 2 FAIL" CAS MESSAGE. COULD NOT DUPLICATE FAN NOISE/SMELL OR MAU 2 FAILURE. CYCLED AVIONICS POWER MULTIPLE TIMES AND FOUND NO DEFECTS. REMOVED DISPLAYS NR 2 AND NR 3 AND VISUALLY INSPECTED AREAS AROUND GLARE SHIELDS FANS AND EFIS DISPLAY FANS WITH NO INDICATIONS OF WIRING OR OTHER OBJECTS CONTACTING THE FAN BLADES. VACUUMED DUST OUT OF EFIS/GLARE SHIELD FANS. REINSTALLED NR 2 AND NR 3 DISPLAYED AND PERFORMED FUNCTIONAL TEST WITH NO DEFECTS NOTED.