What was found
BOI - HYDRAULIC PRESS DROPPED TO ZERO, LEFT AND RIGHT HYDRAULIC. WARNING LIGHTS ILLUMINATED. SYSTEM OPERATED AT ZERO PRESSURE FOR APPROXIMATELY 15-20 MINUTES. ALTERNATE GEAR EXTENSION PERFORMED AND AIRCRAFT LANDED WITHOUT FURTHER PROBLEM. GEAR UP LINE AND FLAP UP LINE REPLACED I/A/W MAINT. MANUAL. COMPLIED WITH CAUTION PUMP PROCEDURES I/A/W MAINT. MANUAL. HYDRAULIC LINES LEAK CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.