What was found
1.4 HOURS INTO A SIGHT SEEING FLIGHT, THE (FUEL FILTER) LIGHT ILLUMINATED ON THE CAUTION PANEL. THE PILOT MADE A PRECAUTIONARY LANDING AS SOON AS POSSIBLE. A MECHANIC WAS SENT TO THE HELICOPTER AND CHANGED THE FUEL CONTROL AND THE AIRFRAME FUEL FILTER. THE HELICOPTER WAS THEN RETURNING TO BASE WHEN THE (FUEL FILTER) LIGHT ILLUMINATED AGAIN. THE PILOT LANDED AT THE HILO MAINTENANCE FACILITY. BOTH FUEL BOOST PUMPS, THE FULE FILTER AND BYPASS INDICATOR ASSEMBLY AND THE FUEL CONTROL UNIT WERE ALL CHANGED AT THIS TIME. THE FUEL FILTER BOWL HAD A FOREIGN SUSSTANCE INTHE BOTTOM OF THE BOWL. IT WAS NOT MAGNETIC. THE FUEL SAMPLE HAS BEEN SENT OUT FOR EVALUATION.