What was found
ENGINE FUEL FILTERS ON LT & RT DIFFERENTIAL PRESSURE ACROSS LT FUEL FILTER APPROACHES BYPASS CONDITION. STATUS ENGINE FUEL FILTER DISPLAYED AFTER TAKE-OFF. REMAINED ON FOR APPROXIMATELY 30 SECONDS. FUEL CONTAMINATION CHECKS WERE MADE AT FUELING STATION, NO CONTAMINATION. BOTH FUEL FILTERS WERE REPLACED, SOME DEBRIS FOUND, BUT BELIEVED INSUFFICIENT TO CAUSE BYPASS. ONE FILTER WAS FLOW CHECKED. MAX DELTA-P ACROSS THE FILTER WAS 3 PSID; INSUFFICIENT TO TRIP THE DELTA-P SWITCH. BOTH DELTA-P SWITCHES WERE CHECKED. CLOSED AND OPENED WITHIN SPEC. SWITCHES WERE DISASSEMBLED - NO ANAMOLIES FOUND.