On September 18, 1999, approximately 1840 Pacific daylight time, a Champion 7BCM, N2841E, impacted trees after departing the runway during the landing roll at Cavanaugh Bay Airstrip, Coolin, Idaho. The Airline Transport Pilot and his passenger were not injured, but the aircraft, which was owned by a relative of the pilot, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed Sandpoint Airport, Sandpoint, Idaho, about 30 minutes earlier, was being operated in visual meteorological conditions. No flight plan had been filed, and there was no report of an ELT activation. The pilot said that he overflew the airport before landing, and both windsocks appeared to show a calm wind. But, according to the pilot, just after touching down, the aircraft encountered a gusty crosswind and veered to the right. As the pilot attempted to compensate for the crosswind, the aircraft departed the right side of the runway and impacted trees growing near the edge of the airstrip. After impacting the trees, the pilot exited the aircraft and noticed that there were strong, gusty, variable winds. These gusty wind conditions were intermittently replaced with periods of calm. The investigation revealed no evidence of control system malfunction or anomaly.