What was found
FLT 2052 EN-ROUTE, CREW RECEIVED ECAM MESSAGE, HYD GRN RSVR LO LVL, IN FLT. THE CREW SELECTED OFF THE NR 1 ENG HYD PUMP. THE FLIGHT LANDED SAFELY, BUT REQUIRED TO BE TOWED TO THE GATE. REPLACED THE NR 1 ENGINE HYD PUMP PRESSURE SWITCH SUPPLY TUBE.