What was found
(CAN) ON LANDING APPROACH COMING INTO THE AIRPORT, UPON LANDING GEAR SELECTED DOWN IT WAS INDICATED THAT THERE WAS A PROBLEM WITH THE NOSE GEAR. THE PILOTS FLEW A GO AROUND AND DECLARED AN EMERGENCY, THE GEAR CAME DOWN SUCCESSFULLY WHEN THE ALTERNATE EXTENSION SYSTEM WAS USED AND THE AIRCRAFT LANDED WITHOUT AND FURTHER INCIDENT. AIRCRAFT TAKEN TO HANGAR AND A GEAR SWING CARRIED OUT FOR FAULT FINDING, THE SELECTOR VALVE WAS FOUND TO BE UNSERVICEABLE, SELECTOR VALVE REPLACED FUNCTIONAL CHECKS CARRIED OUT, AIRCRAFT RETURNED TO SERVICE.