What was found
ON GROUND AT HPN AFTER RIGHT ENGINE START SMOKE STARTED BLOWING OUT OF BOTH COCKPIT GASPERS. PAX AND CREW OVERHEAD ANNUNCIATORS ILLUMINATED AFTER ENGINE SHUTDOWN SMOKE DISAPPEARED AND APU BLOWS NORMAL AIR. REMOVED AND REPLACED APU P/N 3800548-2, S/N P-387 WITH REPAIRED APU P/N 3800548-2, S/N P200 IAW F-2000 M/M 49-000. PERFORMED CHECK OF AIR CONDITIONING DUCTS, INSPECTED WATER SEPARATOR, CHECKED COLD AIR LINES, CONDENSOR, ATOMIZER, NO DEFECTS NOTED. RAN SYSTEM NO DEFECT NOTED IAW F-2000 M/M 21-206 AND 21-205.