What was found
SMOKE IN COCKPIT RIGHT AFTER TAKEOFF. SMOKE ENTERED FROM UNDER AVIONICS, POSSIBLY FLOOR/RUDDER AREA. ENTERED CABIN AS WELL. RETURNED TO DEPARTURE AND LANDED WITHOUT INCIDENT. RAN ACFT AT TAKEOFF POWER FOR 30 MIN. OPERATED BLEED SYSTEMS. PERFORMED CABIN/ COCKPIT ENVIRONMENTAL SYS CHECK. NO DEFECTS NOTED AT THIS TIME. MFG PERFORMED ENGINE WORK BEFORE THIS FLIGHT, THE NR 4 BEARING CARBON SEALS WERE CHANGED.