HISTORY OF FLIGHT On December 28, 1996, at 1145 central standard time, a Beech C90, N998VB, impacted trees and the terrain during an ILS approach to runway 9 at the Rhinelander-Oneida County Airport near Rhinelander, Wisconsin. The airplane sustained substantial damage during the impact which occurred about ten miles west of the intended destination. The pilot and one passenger reported minor injuries. Eight other passengers reported no injuries. The 14 CFR Part 91 personal flight was operating in instrument meteorological conditions on an instrument flight plan. The flight departed Moline, Illinois, about 1045. The pilot indicated that the airplane was unable to maintain flight and was vibrating prior to impact. Several pilots reported severe icing conditions in the area about the time of the accident. During an interview, the pilot-in-command stated that he had been cleared to intercept the localizer approach to runway 9, at 3,500 feet mean sea level (msl), on a heading of 060 degrees. He stated that just prior to the turn onto the final approach heading, he began to feel a "vibration" through the control column, and then it stopped. Upon entering the turn the "shutter" began again. He said that the "shutter" became intense and the airplane was losing altitude. He stated that he added full power. When he saw that he was still descending and his airspeed was indicating 110 knots, he put the landing gear handle in the "down" position, shut off the fuel firewall valves, and prepared for impact. The pilot rated passenger who was occupying the right cockpit seat stated that when the flying pilot began the turn to the final approach heading, "...shutter again began and that it all happened in a matter of seconds before hitting the ground." One passenger told police that she saw ice forming on the left "rear" wings. All the passengers described a "vibration" just prior to the impact. One passenger said that prior to impact the, "...wingtips started to dip left and right as if hitting turbulence." PERSONAL INFORMATION The pilot born February 20, 1947, was the holder of a private pilot certificate with privileges for single and multiengine land with an instrument rating for airplanes. He was the holder of a third class medical certificate issued April 11, 1995. His most recent biennial flight review was on April 17, 1996, in a Beech C90. At the time of the accident he had accumulated a total flight time of 932 hours with 338 hours in the make and model of airplane involved. The pilot rated passenger occupying the right cockpit seat was born December 13, 1944. He was the holder of a private pilot certificate with privileges for single engine land airplanes and an instrument rating for airplanes. He held a third class medical issued on November 4, 1996. His most recent biennial flight review was on July 12, 1996, in a Beech B-35. At the time of the accident he had a total flight time of 611 hours with no hours in type. AIRCRAFT INFORMATION The airplane was a Beech C90, N998VB, serial number LJ-785. The airplane was maintained on an Approved Airworthiness Inspection Plan (AAIP). The airplane had accumulated a total time of 6,301 hours at the time of the accident. The most recent inspection was accomplished on August 27, 1996. The airplane had operated 103 hours since that inspection. METEOROLOGICAL INFORMATION The recorded weather at the destination airport (Rhinelander, Wisconsin) observed five minutes after the accident was ceiling 300 feet overcast, with 2 1/2 miles visibility in snow and fog. The temperature was 23 degrees (F). The pilot stated that he received, "Full Flight Service briefings..." He also indicated that he spoke to flight watch and made a phone call to an FBO at Rhinelander, Wisconsin, prior to takeoff. Weather forecasts indicated the possibility and probability of airframe icing conditions in the area of the accident during the period covering the time of the accident There were five recorded transmissions of conversations from one of the pilots aboard the accident airplane and the Fort Dodge, Iowa, Automated Flight Service Station (AFSS). One call was made on December 27, 1996, and the remaining four on December 28, 1996. The transcripts of all the calls are attached as an addendum to this report. The forecasts for icing included wording such as, '... moderate to isolated severe icing from seven thousand downward for your entire route of flight..." Several rescue personnel responded to the accident on snowmobiles. Two of those persons said that while traveling to and from the accident site they had difficulty keeping their face shields (on their helmets) clear of freezing precipitation. WRECKAGE AND IMPACT INFORMATION The main airplane fuselage came to rest upright in a wooded area on a northerly heading. Impact marks consisting of broken trees leading up the fuselage, were on an easterly heading in the direction of travel. Left and right wing structures, although having received impact damage, remained attached to the fuselage. Both engines, propellers and nacelles were broken away from the wings. The empennage was broken away just aft of the aft pressure bulkhead. Continuity of the flight controls was established through the fuselage. Primary electrical power was available during the post accident examination. No accumulation of airframe ice was found during the post accident examination. The cabin and cockpit remained intact as examined after the accident. There was an intrusion from the outside into the cabin where one propeller blade penetrated the aft baggage compartment. There was no evidence of fire or smoke in any of the wreckage. All propeller blades on both engines displayed rotational twisting, bending, and scoring. All blades had leading edge nicks and polishing on the camber side. Fuel was present in the main fuel tanks. In his statement the pilot reported no mechanical anomalies preceding the accident. No pre-impact anomalies were found during the post accident examination of the engines and airframe. ADDITIONAL INFORMATION Parties to the investigation were the Federal Aviation Administration, Flight Standards District Office, Milwaukee, Wisconsin, and Pratt and Whitney of Montreal, Canada. The wreckage was released to a representative of the owner of the airplane on December 30, 1996.