On September 15, 2002, at 1440 central daylight time, a Christen Industries A-1, N9598C, piloted by a commercial pilot, sustained substantial damage when it struck a powerline pole during takeoff from a private airstrip near Chetek, Wisconsin. The takeoff was being made to the north on the north-south oriented grass airstrip. The pilot and his one passenger were not injured. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The local flight was originating at the time of the accident. The pilot reported that he was taking off from a private turf airstrip. He stated that the airplane accellerated normally, until, "at approximate time of liftoff of main wheels the aircraft for unknown reason began to drift off runway centerline to the right. Pilot attempted to correct drift with control inputs to which aircraft did not respond." The airplane's right wing subsequently impacted a powerline pole. A postaccident examination of the airplane failed to reveal any preexisting anomalies.