PC12 PLT AND FLT INSTRUCTOR EXPERIENCE AUTOPLT MALFUNCTIONS AND SUBSEQUENT ALT EXCURSION.

Narrative

I AND AN INSTRUCTOR PLT DEPARTED TPF FOR A TRAINING FLT. AT 600 FT; WE CONTACTED TPA APCH AND WERE GIVEN A XPONDER CODE; HDG; AND CLRED TO 1600 FT. THE AUTOPLT WAS OFF; BUT THE YOKE WENT TO A FULL DEFLECTION TO THE L. I OVERPOWERED IT; HIT THE AUTOPLT DISCONNECT SWITCH (EVEN THOUGH THE AUTOPLT WAS NOT ENGAGED). I GOT THE PLANE ON THE CORRECT HDG AND WHEN APCHING 1200 FT; WE EXPERIENCED A RUNAWAY TRIM AND QUICKLY CLBED TO 2200 FT. WE THEN GOT THE PITCH UNDER CTL AND DSNDED TO 1600 FT. THERE WAS TFC N OF US AT ABOUT 2200 FT WHICH WE SAW THE ENTIRE TIME. HE WAS NBOUND AND WE WERE NEBOUND AND WE WERE NEVER CLOSER THAN APPROX 1 MI. TPA APCH ASKED US TO CONTACT TPA; WHICH WE DID UPON LNDG BACK AT TPF AFTER TRAINING. BEFORE WE LEFT TPF; WHILE GOING THROUGH A PREFLT CHKLIST; THE AUTOPLT MALFUNCTIONED; BUT SEEMED TO WORK OK AFTER THAT. WE THINK THAT; UPON TAKING OFF; THE AUTOPLT STARTED ANOTHER TEST PROC; WHICH RESULTED IN THE ABOVE DESCRIBED MANEUVERS. IN ALL OTHER PHASES OF THIS FLT; THE AUTOPLT PERFORMED CORRECTLY AND IS WORKING PROPERLY. IT WILL UNDERGO FURTHER TESTS TO ENSURE THAT IT IS WORKING CORRECTLY.