What was found
ON DESCENT RECEIVED AMBER CAS AP TRIM STAB FAIL. RAND QRH. ONCE AP DISCONNECTED HAD PUSHING FORCE (NOSE DOWN) ON CONTROLS. MANUAL TRIM WORKED. LANDED. AP SYSTEM MEL APPLIED ALONG WITH MX REQUIREMENTS. YD MEL 22-10-05 WAS REFERENCED AND IS CONSIDERED INOP. REPLACED HORIZOTNAL STAB TRIM ACTUATOR CONTROLLER, WITH A OVERHAULED UNIT IAW AMM 27-40-30, REMOVED AND REPLACED NZ120 PCB IAW AMM 24-60-30. ACFT RETURNED TO ORGINAL CONDITION. PERFORMED AFCS OPS CHK AND SYS CHKD GOOD WITH NO DEFECTS NOTED. ALL WORK ACCOMPLISHED IAW AMM 22-10-00 AND 45-40-00.