On October 2, 2000, at 0900 central daylight time, a Bell 206L-1 helicopter, N321CA, was substantially damaged when it impacted trees and terrain while maneuvering near Jasper, Texas. The helicopter was registered to and operated by Chem Air, Inc., of Shreveport, Louisiana. The non-instrument rated commercial helicopter pilot, who was the sole occupant, was seriously injured. Instrument meteorological conditions (IMC) prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The helicopter departed from a field approximately 0830. The pilot stated that he waited for the fog to lift, departed, and sprayed a field. The pilot then landed to refuel with his ground crew prior to spraying another field located approximately 17 miles away. The pilot departed and was flying to the other field when he encountered IMC at a low altitude. The pilot initiated a turn to the left to exit IMC and attempted to cage his attitude indicator. During this time, the helicopter impacted a tree with its spray boom, and the pilot then ascended into the fog. The pilot reported that the helicopter was difficult to control and he was having problems seeing the ground. The pilot reported to the ground crew that he was losing control of the helicopter. Subsequently the helicopter impacted the trees. Witnesses, located approximately 50 yards from the accident site, stated that they heard the helicopter fly over their house "very low." They then heard some "loud banging noises and then the helicopter noise disappeared." The witnesses assumed that the helicopter had crashed and went outside to render aid. The witnesses said that they called for the pilot and got a reply. The witnesses found the helicopter and the pilot in a heavily wooded area near their house. They added that they could hear the engine spooling down as they neared the accident site. One of the witnesses reported that it was "very foggy" at the time of the accident. At 0855, the weather observation facility at the A.L. Mangham Jr. Regional Airport, located in Nacogdoches, Texas, 45 miles northwest of the accident site, reported the sky as overcast at 100 feet agl, with 1.25 statute miles visibility. According to the Pilot/Operator Aircraft Accident Report, the 22,911-hour pilot had accumulated 10 hours of simulated instrument flying, and no actual instrument flight experience.