What was found
THE CREW REPORTED SMOKE IN THE CABIN, APPROX 2 MINUTES AFTER SELECTING ENGINE BLEEDS, WITH A SMELL BEING IMMEDIATELY NOTICEABLE. THE ACFT RETURNED TO DEPARTURE, LANDED WITHOUT INCIDENT. MX INSPECTED THE ACFT, PERFORMED GROUND RUNS OF THE ENGINES, ALL WITH NO DEFECTS NOTED, AND UNABLE TO DUPLICATE THE DISCREPANCY, AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE.