ATX SMT ENCOUNTERS SEVERE TURBULENCE AND PARTIAL LOSS OF RUDDER. DIVERTED TO ORIGINATION STATION DUE HIGH CROSSWINDS AT DESTINATION.

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INDICATION=AUTOPLT DISCONNECT IN HEAVY TURB PLUS LOSS OF ALT--500' DUE TO DECREASE IN PLT'S ABILITY TO RECOVER (RUDDER LOOSE AT THIS POINT). POOR RUDDER CTL ON APCH TO LNDG (30 DEGS XWIND GUSTY; 25 GUSTING 30). UPON APCH AT DPA POOR RUDDER CTL WAS APPARENT TO THE PLT AFTER A LNDG APCH WAS ABORTED. THE TWR WAS ASKED BY THE CAPT TO VISUALLY INSPECT THE RUDDER FOR PROPER ACTION. NO RUDDER ACTION WAS OBSERVED; CONFIRMING A DAMAGED RUDDER CONTROL SYS. A LCL ARPT WITH A RWY INTO THE WIND WAS REQUESTED BY THE CAPT AT THIS TIME. NONE WAS AVAILABLE. THE CAPT THEN REQUESTED THE TWR CALL THE CHARTER COMPANY FOR INSTRUCTION AS REQUIRED BY THE COMPANY FLT OPERATION MANUAL. IT WAS DETERMINED THAT WINDS AT THE ACFT BASE OF OPS WERE FAVORABLE FOR LNDG; SO A RETURN FLT WAS MADE. NORMAL LNDG WAS MADE. AFTER LNDG DURING TAXI AND ATTEMPTED SECURING OF THE ACFT; THE RUDDER WAS FURTHER DAMAGED BY THE WIND. INABILITY TO DO A SAFE XWIND LNDG. CAUSE: WIND DAMAGE; CORRECTABLE THROUGH STRICT USE OF EXTERNAL CONTROL LOCK ON THE SMT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: REVEALED THE ACFT WAS IN LNDG CONFIGN AND SEVERE TURB BELOW 1000' AGL WHEN APCH BROKE OFF. STILL HAD SOME RUDDER CONTROL WITH THE TRIM TAB; BUT THAT WAS ALL; EXAMINATION REVEALED SEVERAL WORN COMPONENTS IN RUDDER SYS. FIGURE SHOOK LOOSE ON THE GND AND THEN TURB IN AIR DURING FLT CAUSED THE FAILURE. HAVE BEEN OTHER CASES AND MFG KNOWS OF PROB AND EXTERNAL GUST LOCKS SHOULD BE USED FOR EXTENDED PARKING OR IN GUSTY CONDITIONS FOR SHORT PARKING.