What was found
IN FLIGHT NOTICED SLIGHT RUMBLE, NR 3 ENG N1 BEGAN TO FLUCUATE. ENG BEGAN TO ROLL BACK, ENG OIL PRESSURE LIGHT CAME ON. ENG SHUTDOWN, OIL PRESSURE WENT TO NEAR ZERO PSI. INSPECTED ENG INLET & EXHAUST, SPECIFIC GRAVITY, CHECKED MAGNETIC CHIP DETECTORS, FUEL FILTER, CDP TUBES FOR LEAKS AND ALL CHECKS WERE GOOD. MAINTENANCE THEN CHECKED FUEL PUMP LOW PRESSURE IMPELLER ROTATION, CHECKED N1 & N2 FOR ROTATION, ALL CHECKS GOOD. SUMPED TANK AND NO WATER WAS NOTED, INSPECTED FOR FUEL LEAK IN PYLON AND LEADING EDGE WITH NO LEAKS NOTED. RAN ACFT FOR 5 MINS IN IDLE (NOISE CONSTRAINTS IN LAX). TURNED THE BOOST PUMP ON & OFF, ALL ENGINE PARAMETERS CHECKED NORMAL. NR 3 ENGINE CHECKS GOOD ON GROUND.