What was found
(CAN) SHORTLY AFTER TAKEOFF THE NOSE GEAR DIDN`T RETRACT UPON GEAR UP SELECTION. THE FLIGHT CREW FOLLOWED THE QUICK REF HANDBOOK PROCEDURE, CONDUCTED AN ALTERNATE GEAR EXTENSION AND LANDED BACK WITHOUT FURTHER INCIDENT. HISTORICAL REVIEW INDICATED THAT 2 SIMILAR DISCREPANCIES HAD BEEN PREVIOUSLY REPORTED. MX TRAVELED TO THE OUT STATION AND REPLACED THE NLG SELECTOR VALVE. SIMILAR PROBLEMS WERE REPORTED THE NEXT 2 CONSECUTIVE DAYS. IT WAS FINALLY FOUND THAT THE RT NLG DOOR MICROSWITCH S1GA (IPC 32-61-15-01-010) WAS INTERMITTENT. THE SWITCH WAS REPLACED, THE SYS TESTED AND THE ACFT RELEASED FOR SERVICE FOLLOWING COMPLETION OF A SUCCESSFUL TEST FLIGHT.