What was found
LFT - FLT 4129 - THE PILOT REPORTED AN UNCOMMANDED PITCH-TRIM ON TAKEOFF. THE ACFT LANDED AT LFT WITHOUT INCIDENT WHERE MAINTENANCE REMOVED AND REPLACED THE HORIZONTAL STABILIZER CONTROL UNIT AND WAS RELEASED BACK TO SERVICE. THE UNCOMMANDED PITCH-TRIM FAULT RECURRED ON THE GROUND AT AMA ON 7-20-98, FLT 4210. MAINTENANCE REMOVED AND REPLACED THE NR 1 IC600 COMPUTER, AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE. NO FURTHER INCIDENTS HAVE BEEN REPORTED TO-DATE. (X)