THE ACFT DEPARTED AGUE PRIETA, SONORA, MEXICO WITH NO FLT PLAN ON A FLT TO JANOS, CHIHUAHUA, MEXICO. DRG DEPARTURE, THE PLT'S SON OBSERVED A DARK THREATENING CLOUD BANK IN THE DIRECTION OF FLT NEAR A MTN RANGE. WHEN THE ACFT DID NOT ARRIVE AT THE DESTINATION, A SEARCH WAS BEGUN WHICH WAS EXTENDED ON THE US SIDE OF THE BORDER. ON 1/15/82, A RANCHER FOUND THE WRECKAGE WHICH WAS SCATTERED OVER AN AREA EXCEEDING 1 MI IN LENGTH. AN INVESTIGATION REVEALED THAT THE TAIL ASSEMBLY, RIGHT WING, ABOUT 1/2 OF THE LEFT WING AND WINDSCREEN HAD SEPARATED IN FLT. NO EVIDENCE WAS FOUND THAT WOULD INDICATE A PREIMPACT MALFUNCTION OR FAILURE OF THE AIRCRAFT, ENGINE, PROPELLER OR ACCESSORIES, EXCEPT FOR SEPARATED COMPONENTS WHICH SHOWED EVIDENCE OF IN-FLT PLT INDUCED OVERLOADS. LOCAL RESIDENTS REPORTED A SEVERE SNOW STORM WITH HEAVY WET SNOW AND REDUCED VISIBILITIES AT THE TIME OF THE ACCIDENT. THE PILOT WAS NOT RATED FOR INSTRUMENT FLIGHT. DRG TKOF, THE ACFT WAS APRX 547 LBS OVER ITS MAX GROSS WEIGHT LIMIT, CG APRX 2 IN BEHIND AFT LIMIT.