What was found
DIVERSION/EMERGENCY DECLARED BY AIRPORT AUTHORITY HYD WARNING. YELLOW RESERVOIR LOW LEVEL WARNING, FOLLOWED BY LOW AIR PRESSURE, ULTIMATELY LOST ALL SYSTEM HYDRAULIC PRESSURE. REPLACED O-RINGS ON PTU PRIORITY VALVE, LEAK CKS GOOD. ALSO, REPLACED HP RETURN AND CASE DRAIN FILTERS, NO DEFECT NOTED, NO DEBRIS IN OLD FILTERS.