What was found
ON CLIMB-OUT OF SHANHAI ON FLIGHT 7875, NR 4 ENGINE OIL PRESSURE LIGHT CAME ON. SHUT DOWN NR 4 ENGINE AS PRECAUTIONARY, DUMPED FUEL AND LANDED AT HKG WITHOUT INCIDENT. INSPECTED OIL FILTER, NO CONTAMINATION FOUND, SUSPECT OIL PRESSURE DIFFERENTIAL SWITCH AT FAULT, DEFERRED SWITCH PER MEL 79-7. UNIT WAS REPLACED AT SIN, SYSTEM OPS CHECKED GOOD PER M.M. CH 79.