What was found
PILOT REPORTS A GEAR DISAGREE MSG AFTER TAKEOFF FOLLOWED WITH A NOSE DOOR WARNING. HE STATED THAT THE NLG TOOK 3 -4 MINUTES TO COME UP & THE MSGS WENT AWAY. ACFT LANDED WITH NO INCIDENT. NO EMER WAS DECLARED. GEAR DISAGREE UP & NOSE DOOR WARNING AFTER TAKEOFF. NOSE GEAR DOWN & MAIN GEAR UP. TIME INTERVAL WAS 6 SECONDS. GEAR LEVER WAS NOT MOVED WITHIN 30 SECONDS OF ORIGINAL SELECTIONS. MANUAL OPERATING SYS WAS NOT MOVED. LANDED AT 47000 POUNDS AND THEY LANDED AT MINIMAL DESCENT RATE. REPAIRED & REPLACED SLIDING PISTON MEMBER IAW AMM 32-21-30. ALL CHECKED GOOD AT THIS TIME.