On November 20, 1997, at 0830 central standard time (cst), a Beech 95-B55, N3681K, operated by a private pilot, sustained substantial damage when during cruise flight, smoke entered the cabin. During the subsequent precautionary landing into an unimproved field, the airplane impacted some trees and the terrain. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under 14 CFR Part 91. No flight plan was on file. The pilot and passenger on board the airplane reported no injuries. The cross- country flight originated at Rogers, Arkansas, at 0745 cst, and was en route to Concordia, Kansas. In his written statement, the pilot said that they were approximately 40 minutes into their flight when "my passenger and I heard the pneumatic door seal give way." The pilot recycled the switch, but nothing happened. A few minutes later, the pilot and passenger noticed "the faint smell of electrical burn." The pilot switched the heater off and the smell seemed to subside. The pilot switched the heater back on and noticed a stronger smell immediately. Black smoke began to enter the cabin from above and beneath the instrument panel. The pilot said that as he reached for the throttle, he noticed "that there was orange spark and flame under the panel." The pilot initiated a steep descent and began looking for a place to land. The pilot located a north-south running dirt road, and initiated a 180-degree turn to land. The pilot said that his descent rate was higher than he was used to, and that he miscalculated the turn to line up on the road. The pilot began to turn back to the road, but then noted that he didn't have enough altitude and airspeed. The pilot leveled the airplane and then landed in the field in front of them. The Federal Aviation Administration (FAA) inspector who examined the wreckage at the site, found the airplane resting upright in an uncultivated field. A ground scar was observed on a 15-degree upsloping hill and preceded along a 210-degree magnetic heading between two stands of cedar trees. Several of the trees showed impact damage. The airplane was resting south of the trees and oriented on a 150-degree heading. The outboard 18 inches of the right wing, wingtip and aileron were broken off and resting near the trees. The left wing was crushed inward along the outboard leading edge. The fuselage showed upward crushing along the bottom. The cabin and forward fuselage was found intact. The nose gear was hyperextended and broken forward. The left main landing gear was broken off. The right main landing gear was broken and twisted 90 degrees. The right horizontal stabilizer was bent upward and aft. Both propellers showed torsional bending and chordwise scratches. Flight control continuity was confirmed. No anomalies were observed with the engines, engine controls or propeller controls. Examination of the nose compartment bulkhead showed that the door seal inflation pump, mounted on the top, front-side of the bulkhead, was heavily charred. Charring and discoloration were observed on the metal bulkhead behind and around the pump. Examination of the cabin revealed that the door inflation seal around the cabin door was gone. Both air vents, under the instrument panel, in the forward cabin, were found in the open position. Plastic insulation surrounding electrical wiring in front of the right air vent was melted. Melted plastic was observed on the floor, beneath the right side air vent, in front of the right front seat. No other anomalies were found with the airplane.