SMT PLT HAS PROP PITCH PROBLEM. WHILE TROUBLESHOOTING; ENTERS TCA.

Narrative

I DEPARTED MCCOLLUM ARPT; ATLANTA TCA ON 260 DEG HDG TO AVOID DOBBINS AFB AIRSPACE AND ATLANTA TCA. ON REACHING 5000 FT TO STAY UNDER TCA AIRSPACE; THE L ENG PROP SUDDENLY WENT INTO FLAT PITCH ALLOWING ENG RPM TO RED LINE. IT DID NOT RESPOND TO LOWER RPM PROP CTL SETTING FOR ABOUT 1 MIN. THEN IT OVERREACTED AND DROPPED TO 2000 RPM. AFTER WORKING WITH IT FOR A MIN OR SO; IT FINALLY STABILIZED AT THE DESIRED 2300 RPM SETTING. I THEN CHANGED COURSE TO A HDG TOWARD FULTON COUNTY ARPT AND ATLANTA ARPT TO USE LONGER RWY IN THE EVENT OF AN EMER LNDG IF IT OCCURRED. I HAD A SIMILAR SITUATION SOME YRS AGO AND THE WINDMILLING PROP MAKES SINGLE ENG PERFORMANCE MORE CRITICAL WITH NO FEATHERED PROP. SINCE I WAS NOT SURE OF MY EXACT LOCATION AT THIS TIME I CONTACTED ATLANTA APCH TO GIVE MY VFR 1200 SQUAWK CODE TO BE SURE HE SAW ME AND TO GET TA AND FLT WATCH. I PROCEED S STAYING WHAT I THOUGHT WAS FAR ENOUGH OUT TO AVOID ARPT CTL ZONE BUT CLOSE ENOUGH IN THE EVENT OF AN EMER. I DID NOT DECLARE AN EMER BECAUSE THE PROP REMAINED STABLE AT 2300 RPM. I PROCEED TO VACATE THE TCA AS QUICKLY AS SEEMED PRUDENT. ATLANTA APCH THEN TURNED ME OVER TO COLUMBUS FOR FLT WATCH AND I CONTINUED ON COURSE TO FLORIDA WITHOUT FURTHER PROP PROBLEMS. ON RETURN TO ATLANTA; I HAD PROP CHKED AND PROP GOVERNOR REPAIRED.