On May 16, 1994, at 0720 eastern daylight time, a Schweizer 269C, N160CA, was substantially damaged following a collision with trees and the terrain near Hiram, Georgia. The commercial pilot received serious injuries in the accident. The helicopter was being operated under 14 CFR Part 91 by the pilot. Instrument meteorological conditions existed at the time of the accident, and no flight plan had been filed for the business flight. The flight departed the pilot's residence in Hiram, and was enroute to the pilot's place of business in Villa Rica, Georgia. The pilot reported that, at the time of departure, the weather at his residence was sufficient for flight under visual flight rules. He stated that after departure, he encountered a fog bank, started a 180 degree turn, and descended slowly attempting to land. During the turn, he contacted the trees and crashed.