What was found
AFTER TAKEOFF, FLIGHT ENCOUNTERED COMPLETE LOSS OF SYSTEM A HYDRAULICS AND PRESSURE. LOST LG TRIANGULAR PANEL OFF TOP OF RT WING. NOSE GEAR WOULD RETRACT BUT MAIN GEAR WOULD NOT. HYDRAULIC LINE HAD BROKEN. PANEL DEPARTED AIRCRAFT AT END OF RUNWAY. CAPTAIN DECLARED EMERGENCY AND RETURNED TO FIELD. MANUAL GEAR EXTENSION WAS PERFORMED AS WELL AS QUICK REFERENCE HANDBOOK PROCEDURES. FLIGHT LANDED WITHOUT FURTHER INCIDENT AND WAS TOWED FROM END OF RUNWAY. MAINT REMOVED AND REPLACED HYDRAULIC LINES DAMAGED BY DEPARTING WING PANEL. REPLACED RIGHT WING PANEL. SERVICED HYDRAULICS AND CYCLED LANDING GEAR AND FLIGHT CONTROLS TO REMOVE ALL AIR FROM HYDRAULIC SYSTEM. OPERATIONAL CHECK AND LEAK CHECK GOOD.