What was found
AFTER T/O, THE COCKPIT AND CABIN FILLED WITH SMOKE. CREW SHUT DOWN ENVIROMENTAL CONTROL SYSTEMS AND RECIRCULATION FANS. ALSO, APU WAS SHUT DOWN. THE SMOKE CLEARED FROM THE A/C. THE A/C RETURNED TO THE FIELD AND LANDED, W/O ANY FURTHER INCIDENTS. MX INSPECTED AND DETERMINED DE-ICE FLUID WAS INGESTED INTO APU, AND CAUSED THE SMOKE. MX RAN THE ENVIROMENTAL SYSTEMS, IAW DORNIER MM 21-21-00 TO REMOVE ANY RESIDUAL SMELLS FROM THE SYSTEM, AND DEFERRED THE APU IAW THE DORNIER 328 MEL. A/C WAS RETURNED TO SERV. 06 FEB 98, THE APU WAS OP'S CHECKED IAW DORNIER MM 49-10-00 AND 21-21-00. THE DEFERRAL WAS REMOVED, AND THE A/C WAS RETURNED TO SERV.