CARJ CREW FOUND 'VERY POOR' ROLL CTL TO THE R AND EVEN WORSE CTL TO THE L. PROB DISSIPATED WHEN DSNDING BELOW THE FREEZING LEVEL. THERE WAS HVY RAIN AT THE DEP STATION.

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DURING DSCNT FROM FL250; AUTOPLT MAX WING DOWN TRIM CAUTION MESSAGES WERE ILLUMINATED. FOLLOWING QRH PROCS; AUTOPLT WAS DISCONNECTED. CREW DISCOVERED R ROLL CTL WAS VERY POOR AND L ROLL CTL WAS WORSE. CREW DISCUSSED POSSIBILITY OF ICE BUILD-UP IN CTLS DUE TO HVY PRECIP AT DEP AND DURING CLB. AS DSCNT CONTINUED TO WARMER AIR (APPROX 0 DEGS C) FULL AND NORMAL CTL OF ROLL WAS EXPERIENCED! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATES THAT THE ACFT HAS CABLE CTLS THAT RUN THROUGH THE WHEEL WELL AREA. THE HYD CTL UNITS ARE IN THE WING; DOWNSTREAM OF THE CABLES. WATER IS ABLE TO ENTER THE WHEEL WELL AREA AND THE CABLES BIND OR LOCK UP WHEN THE CABLES ARE FROZEN BY WATER. THE CAPT INDICATES THAT PREVIOUSLY ISSUED AIRWORTHINESS DIRECTIVE NOTES REQUIRE THE INSTALLATION OF A SEAL IN A GAP AREA IN THE WHEEL WELL; AND GREASING THE CTL CABLES TO PREVENT ICE FROM STICKING TO THE CABLES. THE AIRWORTHINESS DIRECTIVE ALSO REQUIRES THE AUTOPLT BE DISCONNECTED EVERY 5000 FT; DURING CLB; TO EXERCISE THE LATERAL CTL; AS THE PROB STILL EXISTS. THE CAPT KNOWS OF ANOTHER CREW THAT EXPERIENCED LOCKED LATERAL CTLS WHICH WOULD NOT RELEASE UNTIL THE ICE LOCKING THE CTLS MELTED.