What was found
(CAN) DURING ENGINE START, FIRST FLIGHT OF THE DAY, OIL PRESSURE WAS OBSERVED AS BEING TOO HIGH (75 PSI AT IDLE). SYSTEM BLOCKAGE WAS SUSPECTED, OIL FILTER INSPECTED (CLEAR), OIL DRAINED AND INSPECTED (CLEAR), PRESSURE CHECKED AT OTHER PRESSURE POINTS IAW MFG SERVICE REP. INSTRUCTIONS. (AIRFRAME INDICATOR ACCURACY CONFIRMED.) NIL DEFECT FOUND. OIL PRESSURE RELIEF VALVE REMOVED, VISUALLY INSPECTED (NIL DEFECTS OBSERVED, REINSTALLED. ENGINE GROUND RUN, NIL CHANGE IN OIL PRESSURE. RELIEF VALVE ADJUSTING SCREW TURNED OUTWARD TO STOP. OIL PRESSURE OBSERVED (JUST IN RANGE). VALVE ASSEMBLY REPLACED WITH SERVICEABLE UNIT, OPERATION NORMAL.