A CANADAIR CL65 FO RPTS AUTOPLT AND FLT DIRECTOR SWITCHING TO UNCOMMANDED MODES RESULTING IN AN ALT OVERSHOOT.

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WE DEPARTED PFN RWY 14 WITH INSTRUCTIONS FOR A L TURN TO 090 DEGS AND A CLB TO 2000 FT. VERT SPD AND HEADING MODES WERE SELECTED; BUT INSTEAD OF THE FLT DIRECTOR COMMAND BARS SYNCHRONIZING TO THE CURRENT VERT SPD; THEY REVERTED DIRECTLY TO ALT CAPTURE MODE AND DIRECTED A CONTINUOUSLY INCREASING PITCH ATTITUDE. I'VE SEEN THE SAME ANOMALY BEFORE IN THE SIMULATOR AND IN THE AIRPLANE; SOMETIMES WHEN SEVERAL THOUSAND FT FROM THE ASSIGNED ALT. AND THE BAD THING IS THE AUTOPLT; IF ENGAGED; WILL DUTIFULLY FOLLOW THE COMMAND BARS UP TO 15+ DEG PITCH. THAT COULD BE A PROB DEPENDING ON CURRENT AIRSPD; CONFIGN; ETC. IN MY SIT AT PFN; WE CLRED THE FLT DIRECTOR AND RESELECTED VERT SPD; HEADING; AND AUTOPLT ENGAGED. BUT BY THAT POINT WE WERE CLBING AND ALMOST TO 2000 FT. I WATCHED AS THE AUTOPLT BEGAN TO LEVEL OFF BUT IT WAS UNABLE TO STOP CLBING AT 2000 FT. SO; I RESUMED MANUAL CTL AND DSNDED FROM 2180 FT TO 2000 FT. THIS PROCESS DIVERTED MY ATTN FROM THE AIRSPD SIT AND WE MOMENTARILY EXCEEDED 200 KTS. ATC THEN CLRED US TO A HIGHER ALT AND WE CONTINUED ON OUR WAY.