What was found
RIGHT WING GEAR WOULD NOT RETRACT AFTER TAKEOFF. CYCLED GEAR, NO HELP. WING GEAR DID NOT RETRACT DUE TO LOW SYSTEM 4 PRESSURE. NR 4 HYDRAULIC SYSTEM FOUND CONTAMINATED DUE TO EDP OVERHEAT CONDITION. OVERHEAT CONDITION BELIEVED DUE TO PARTIALLY COLLAPSED EDP PRESSURE LINE. REPLACED EDP, ADP, ACMP, EDP SUPPLY LINE, PRESSURE LINE AND CASE DRAIN LINE. PRESSURE MODULE FILTERS, CASE DRAIN MODULE. FLUSHED SYSTEM NUMEROUS TIMES, AIRCRAFT RETURNED TO SERVICE.