A CANADAIR CL65 AFTER TKOF AT 500 FT; DIVERTED DUE TO LOSS OF NOSE DOWN TRIM ON CAPT'S TRIM SWITCH. 'STABILIZER TRIM' AND 'MACH TRIM' CAUTION ON EICAS.

Narrative

AFTER TKOF AT APPROX 500 FT AGL; NOSE DOWN TRIM WAS ATTEMPTED ON THE CAPT'S TRIM SWITCH. THE TRIM INPUT HAD NO EFFECT ON ACFT TRIM; AND 'STABILIZER TRIM.' CAUTION MESSAGE FOLLOWED BY 'MACH TRIM.' CAUTION MESSAGE APPEARED ON EICAS. SEVERAL ATTEMPTS TO RE-ENGAGE STABILIZER TRIM 1 AND 2 AND MACH TRIM WERE UNSUCCESSFUL. WITH ACFT TRIM SET AT 7.0 (TKOF SETTING); CTL FORCES WERE HVY TO MAINTAIN LEVEL FLT. WITH CTLABILITY AND PROLONGED MANUAL INPUT CAUSING FATIGUE; THE DECISION WAS MADE TO LAND IMMEDIATELY; WHILE ARPT WAS IN VISUAL CONTACT. ATC WAS INFORMED AND PRIORITY HANDLING WAS REQUESTED AND GRANTED. ATC; FLT ATTENDANT; PAX WERE INFORMED BY FO AS WELL AS COMPLETING NORMAL CHKLISTS. EXPEDITED HANDLING ALLOWED THE ACFT TO LAND RWY 18R AT ZZZ WITHIN 3-4 MINS WITHOUT INCIDENT. TIME CONSTRAINTS DID NOT ALLOW QRH/CHKLIST TO BE CONSULTED UNTIL AFTER LNDG. ACR MAINT WAS CONSULTED AND INFORMED THE CAPT THAT THE ACFT MAINT COMPUTER HISTORY INDICATED SEVERAL PREVIOUS FAILURES LOGGED BY THE COMPUTER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED AFTER THE RETURN TO THE FIELD MAINT OPERATED THE STABILIZER TRIM AND WAS ABLE TO DUPLICATE THE FAILURE 1 TIME; BUT THE SYS THEN OPERATED NORMALLY. THE RPTR SAID THE MAINT PEOPLE DID ADVISE THE AIRPLANE DID HAVE SEVERAL RPTS ON THE STABILIZER TRIM IN THE MAIN HISTORY COMPUTER. THE RPTR SAID THE AIRPLANE WAS TAKEN OTS; AND THE FIX WAS NOT RPTED TO THE CREW.