On June 12, 2005, about 1730 Alaska daylight time, a fixed tricycle gear-equipped Cessna U206F airplane, N51205, sustained substantial damage during an in-flight and postcrash fire, after an emergency landing on a remote gravel bar, about 11 miles, south-southwest of Skwentna, Alaska. The airplane was being operated as a visual flight rules (VFR) on-demand cargo flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated by the pilot, doing business as Alaska Airborne Adventures, Wasilla, Alaska. The commercial certificated pilot, the sole occupant, received serious injuries. Visual meteorological conditions prevailed. The flight departed the Willow Airport, Willow, Alaska, about 1715, en route to the Hayes River, Alaska, and no flight plan was filed, nor was one required. The Federal Aviation Administration's (FAA) Alaska Regional Operations Center received notification from a remote lodge operator that the accident airplane was burning on a gravel bar in the Skwentna River. Passing aircraft initially saw smoke in the area, and then spotted the airplane and a single occupant in the river outside of the airplane. The operator of a helicopter who was flying in the area, overheard radio conversations about the accident and responded to the scene. The pilot was airlifted to a local hospital by the helicopter pilot. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 13, the lodge owner and the helicopter pilot reported that the airplane was carrying an external load of plywood under the belly of the airplane. During cruise flight, the plywood caught fire, and the pilot made an emergency landing on a gravel bar. In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the pilot, he reported that he was transporting 500 pounds of lumber inside the airplane. He was transporting 200 pounds of 4 feet, by 8 feet, 1/2 inch-thick plywood in a external lumber rack, attached to the belly of the airplane. During cruise flight at 1,500 feet msl, the pilot indicated he noticed the smell of smoke in the cockpit. He flew toward the Skwentna River as flames entered the cabin of the airplane, and made an emergency landing on a gravel bar. He jumped out of the airplane during the landing roll, and the airplane continued to roll until it hit a log and nosed over, with the fire still burning. According to FAA personnel from the Flight Standards District Office (FSDO), Anchorage, Alaska, the FAA had no records that the operator had any external load authorization. No records were found indicating that the airplane had a restricted category authorization for external loads, nor any authorization for installation of the external lumber rack.