What was found
DURING POST MAINTENANCE TEST, FLIGHT CABIN AND COCKPIT FILLED WITH SMOKE AFTER 20 MINUTES OF FLIGHT, SOURCE UNKNOWN. AIRCRAFT LANDED WITHOUT INCIDENT, SMOKE NOTED BY FLIGHT CREW AFTER AIRCRAFT PARKED. REPLACED NR 3 ENG'S ENGINE DRIVEN COMPRESSOR. RUN OPS, CHECK AIR CONDITIONING SYSTEM WITH BOTH EDC'S ON LINE. NO OIL SMOKE NOTED, OPS CHECKED NORMAL.