As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK, EMERGENCY DECLARED. SMOKE IN CABIN COCKPIT. REMOVED AND REPLACED COALESCER BAG LT & RT IAW AMM 21-51-00. OPS CHECK NORMAL FOUND GLYCOL IN APU COOLING INLET, CLEANED RELATED DUCTS AND APU ENCLOSURE, RAN APU & PACKS NO DEFECTS NOTED AT THIS TIME PERFORMED ENGINE GROUND RUN IAW AMM 71-00-00 OPERATION NORMAL NO DEFECTS NOTED.