WHEN THE PLT WAS ADVISED THE DESTN ARPT (SANTA YNEZ) WAS DIRECTLY AHEAD AT 12 MI, HE REQUESTED A FREQ CHANGE & RADAR SVC WAS TERMINATED. ABOUT 9 MIN LATER, HE REESTABLISHED RADIO CONTACT (WITH ARTCC) & REPORTED HE WAS NOT SURE OF HIS PSN. THE CONTROLLER TOLD THE PLT THE ACFT WAS TOO LOW FOR HIS RADAR & ADVISED HIM TO CONTACT SANTA BARBARA RAPCON FOR ASSISTANCE. AFTER CONTACTING RAPCON, HE REPORTED HE WAS DISORIENTED & WAS UNABLE TO FIND THE DESTN ARPT. THE ACFT WAS RADAR IDENTIFIED & THE PLT CONFIRMED A MODE C ALT OF 1300'. HE WAS CAUTIONED ABOUT THE TERRAIN ELEV & WAS GIVEN A HDG TOFLY. THE PLT SAID HE WAS FAMILIAR WITH THE TERRAIN. SHORTLY THEREAFTER, RADIO & RADAR CONTACT WERE LOST. SUBSEQUENTLY, THE ACFT ENTERED A DSCNT, CRASHED & BURNED ABOUT 8 MI SOUTH OF SANTA YNEZ, NEAR THE COAST. IMPACT WAS ON ROLLING TERRAINAT AN ELEV OF APRX 95' MSL. THE TERRAIN ROSE TO APRX 4000' BTN THE CRASH SITE & THE ARPT. NO PREIMPACT PART FAILURE OR MALFUNCTION WAS FND. TOXICOLOGY CHECKS OF THE PLT'S SPLEEN & LIVER FLUIDS SHOWED ALCOHOL LVLS OF 0.124% & 0.130%.