BE90 PLT EXPERIENCES MOMENTARY LOSS OF CTL IN TURB ON APCH IN ZTL AIRSPACE.

Narrative

I WAS DSNDING ON THE AWSON 1 ARR JUST INSIDE OF AWSON. THERE WAS A BROKEN LAYER OF CUMULUS CLOUDS STARTING AT ABOUT 7000 FT MSL. MY DSCNT WAS SUPPOSED TO STOP AT 5000 FT MSL. AS I ENTERED THE CLOUDS; I BEGAN TO ENTER AN AREA OF TURB. WITH THESE CLOUDS; YOU NORMALLY EXPECT SOME TURB. HOWEVER; IN JANUARY IT USUALLY DOESN'T AMOUNT TO MUCH. THE AUTOPLT WAS ENGAGED TO CAPTURE THE ALT. AS WE REACHED THE BASES OF THE CLOUDS THE TURB BECAME MORE SEVERE. I BEGAN TO REDUCE THE PWR TO AVOID OVERSTRESSING THE ACFT. I ALSO CLICKED OFF THE AUTOPLT. WE THEN EXPERIENCED SEVERE TURB. AS I BEGAN THE LEVELOFF AT 5000 FT; THE BOTTOM JUST FELL OUT AND WE ENDED UP AT 4500 FT. THERE WAS ANOTHER ACFT SOMEWHERE BELOW ME ON THE ARR. ATC ASKED ME WHAT ALT I WAS DSNDING TO AND WARNED OF THE TFC CONFLICT. I IMMEDIATELY CLBED AND RPTED THE TURB. NOTHING ELSE WAS SAID AND I NEVER SAW THE OTHER ACFT. I LEARNED NEVER TO UNDERESTIMATE THE PWR OF WX. JUST BECAUSE IT'S NOT TWRING IN JULY; THIS DOESN'T MEAN THE CLOUDS WON'T BE TURBULENT IN JANUARY. I SHOULD HAVE SLOWED THE ACFT AND BEEN IN CTL IN THE CLOUDS INSTEAD OF USING THE AUTOPLT.