As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LGA - FLT 4521 - DURING INITIAL POWER UP ON AIRCRAFT WITH BATTERY AND AVIONICS SWITCHES ON, SMOKE WAS OBSERVED POURING OUT OF THE CENTER CONSOLE. MAINTENANCE COULD NOT DUPLICATE DISCREPANCY. PERFORMED APU START AND RAN ELECTRICAL SYSTEM AND FOUND NO EVIDENCE OF SMOKE. AIRCRAFT WAS RETURNED TO SERVICE. (M)