THERE WERE TWO PILOTS ABOARD THIS ACFT WHICH IMPACTED IN A STEEP NOSE DOWN ATTITUDE ON A PLATEAU AT 5000 FT MSL. FLIGHT CONTROL CONTINUITY WAS ESTABLISHED. THE PILOT WAS RECENTLY CERTIFICATED & HIS CLASS III MEDICAL HAD EXPIRED. THE SECOND PILOT HELD A COMMERCIAL CERTIFICATE & AN INSTRUMENT RATING. HIS RECENT EXPERIENCE COULD NOT BE DETERMINED. THE CRASH SITE WAS IN AN AREA WITH NO SIGNIFICANT LIGHTS CREATING A 'BLACK HOLE.' ONE PROPELLER BLADE WAS TWISTED & BENT WITH SCRATCHES ON THE CAMBER SIDE & A FILAMENT FROM A NAVIGATION LIGHT WAS STRETCHED. THE ACFT WAS NOT CERTIFIED FOR ICING CONDITIONS & HAD NOT BEEN INSPECTED FOR INSTRUMENT FLIGHT. A METEOROLOGICAL SUMMARY INDICATES THAT THE AREA OF THE ACCIDENT AT THE APPROXIMATE TIME OF THE FLIGHT WOULD HAVE BEEN SUBJECT TO THUNDERSTORMS WITH RAIN SHOWERS, LIGHT TO MODERATE TURBULENCE, FLIGHT VISIBILITY 0 MILES IN CLOUDS. NO WEATHER BRIEFING WAS OBTAINED.