As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRIOR TO DEPARTURE, SMELLED SOMETHING LIKE PAPER BURNING. CHECKED THE E/E COMPARTMENT AND OBSERVED COOLING FAN WAS SHUTOFF. COULD NOT LOCATE SOURCE OF SMOKE AND ALL SYSTEMS OPERATED NORMALLY. TEST FLEW AIRCRAFT, OK. LATER, FOUND A BIRD NEST IN THE RADIO RACK COOLING FAN EXIT DUCT AND REMOVED SAME. REPLACED RADIO RACK COOLING FAN PRECAUTIONARY. (K)