SMA SUFFERS JET BLAST ENCOUNTER AND EXPERIENCES LOSS OF ACFT CTL DURING LNDG PROC ROLLOUT. RWY EXCURSION OCCURS.

Narrative

SAT TWR HAD CLRED ME TO LAND ON RWY 12L; WHILE ON L BASE LEG. AFTER I TURNED FINAL; AN AIRLINES WDB WAS CLRED ONTO RWY 12R AND FOR TKOF. THE ATIS HAD RPTED WIND 150 DEGS AT 15 KTS. I CONSIDERED A GAR; HOWEVER; FELT WAKE TURB WOULD NOT BE A FACTOR IF I USED FULL FLAPS WITH A TOUCHDOWN AT ABOUT THE 500 FT POINT. THE LNDG WAS MADE USING FULL FLAPS. AFTER LNDG; FLAPS WERE RAISED TO MINIMIZE WIND EFFECT AND GET WT ON THE WHEELS. SUBSEQUENTLY; ACFT VEERED TO R (ESTIMATED SPD 25 MPH). I STOPPED YAW ROTATION AT APPROX 45 DEGS TO RWY HDG USING L RUDDER AND L BRAKE WITH L TIRE IN A SIDE SKID. I DID NOT USE PWR DUE TO PROX AND UNKNOWN CONDITION AT R EDGE OF RWY; I.E.; LIP; DROP OFF; ROUGH. AS L TIRE SLID OFF SIDE OF RWY; I ELECTED TO STOP SKID BY USING FULL R RUDDER TO YAW PLANE SO THAT IT WOULD ROLL BACKWARD AND ELIMINATE SIDE LOAD ON TIRES AND LNDG GEAR. ACFT STOPPED WITH L GEAR OFF RWY. TAXIED ACFT E ON RWY 12L TO TXWY M. INSPECTION REVEALED MUD IN L WHEEL FAIRING (PICKED UP AT SIDE OF RWY) CAUSING FRICTION WITH TIRE. TAXIED TO RAMP. NO DAMAGE TO ACFT. APPARENTLY ENCOUNTERED WAKE TURB DURING ROLLOUT CAUSING ACFT (CONVENTIONAL GEAR) TO VEER TO R RAPIDLY.