What was found
ABOUT 30 MINUTES AFTER COMPLETE SHUTDOWN, APU WAS RE-STARTED AND BLEEDS WERE PLACED TO LOW. AIRCRAFT CABIN AND FLIGHTDECK STARTED TO FILL WITH SMOKE. OPERATED APU FOR ABOUT 30 MINUTES, NO DISCREPANCIES NOTED. ACCESSED AND REMOVED AND CLEANED WATER SEPARATOR COALESCER SOCK, REINSTALLED WATER SEPARATOR SOCK. RAN BOTH ENGINES AND APU, NO DEFECTS NOTED. INSPECTED APU PLUMBING FOR NAY EVIDENCE OF OIL, NO OIL NOTICED. WITH A BOROSCOPE INSPECTED APU INTERNAL VISUAL INSPECTION, NO DEFECTS NOTED. DOM REQUESTED ANOTHER RUN ON BOTH ENGINES AND APU. RAN BOTH ENGINES AT 80 PERCENT N2 FOR 45 MINUTES AND IDLE, NO DEFECTS NOTED. JUST WITH ENGINES RUNNER AIR GOOD. RAN APU AND CONFIRMED A BAD ODOR. R & R THE APU IAW MM 49-10-00. OPS & LEAK CHECKED GOOD.