What was found
AFTER TAKEOFF AT APPROX 400 AGL, SMOKE IN CABIN & COCKPIT. DUMPED CABIN & SMOKE DISSIPATED. SMOKE SEEN COMING FROM FLOOR AREA AT SEAT 6 & 9. ON PREFLIGHT, ENGINE OIL LEVELS WERE NOMINAL & NO OIL ADDED. POST FLT INSPECTION OF ENGINE OIL LEVELS REVEALED NO USAGE & WERE NORMAL. PRIOR TO APU SHUTDOWN ON TAXI OUT, NOTICED APU LOW LEVEL CAS ILLUMINATE BUT DIDN'T IMPACT APU OPERATION & APU SHUTDOWN BEFORE TAKEOFF UNEVENTFULLY. NO CIRCUIT BREAKERS TRIPPED OR ABNORMAL INDICATIONS. ACCOMPLISHED REMOVAL OF NR 1 ENGINE. OPS AND LEAK CHECKED, NO DEFECTS NOTED. COMPLIED WITH 5 POINT CALIBRATION RUNS, PARAMETERS WITHIN LIMITS. WORK ACCOMPLISHED IAW AMM 71-00-00 & EMM 72-00-00. NO SMOKE IN CABIN OR COCKPIT.