What was found
GEAR DISAGREE WARNING AFTER TAKE OFF. COMPLIED WITH QRH RESULTING IN A GEAR DOWN AND LOCKED, THREE GREEN INDICATION. RETURNED TO FIELD AND LANDING WAS NORMAL. (FLT 4445) CLOSED READJUSTED THE PROXIMITY SENSOR IAW AMM. OPS CHECK GOOD. REPLACED THE NLG SELECTOR VALVE IAW AMM, OPS CHECK GOOD , NO LEAKS NOTED. PERFORMED A PRESSURE DECAY RATE TEST IAW AMM, NO DEFECTS NOTED. ALSO PERFORMED AN EXTENSION AND RETRACTION OF THE LANDING GEAR IN IAW AMM, OPS CHECK GOOD, NO DEFECTS NOTED. A/C OK FOR SERVICE.