What was found
SHV- APU BLEED CAUSES SMOKE WHEN BOTH PACKS TURNED OFF. SHV- MAINTENANCE INSPECTED THE AIRCRAFT, AND, THE AIRCRAFT WAS RELEASED IAW MEL. IAH- MAINTENANCE REMOVED EXCESS OIL FORM APU TO OBTAIN THE PROPER SERVICE LEVEL,PERFORMED A OPERATIONAL CHECK OF THE APU, AND APU BLEED SYSTENS,NO DEFECTS NOTED,AND, THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.