What was found
THE CREW REPORTED THAT WHILE IN FLIGHT, BLEED AIR WAS LEAKING INTO THE CABIN AND CREATING NOXIOUS FUMES. MAINTENANCE RAN BOTH ENGINES WITH THE BLEED AIR SOURCE IN ALL POSSIBLE CONFIGURATIONS. NO DEFECTS WERE FOUND. THE VAPOR CYCLE SYSTEM WAS CHECKED FOR OPERATION AND DRAINAGE, AND THE FRESH AIR DUCT AND FAN WERE CHECKED WITH NO NOTED DEFECTS. BOTH ENGINES WERE RAN AGAIN WITH THE COWLING REMOVED, AND NO DEFECTS WERE FOUND. ALL OPERATIONAL CHECKS WERE GOOD, AND THE AIRCRAFT WAS RETURNED TO SERVICE.