On May 5, 2000, about 1400 Alaska daylight time, a high skid, pop-out float equipped Bell 206B helicopter, N49686, sustained substantial damage while landing, about 20 miles southeast of Haines, Alaska, at latitude 58 degrees, 55 minutes north, and longitude 135 degrees, 11 minutes west. The helicopter was being operated as a visual flight rules (VFR) positioning flight under Title 14, CFR Part 91, when the accident occurred. The helicopter was operated by Coastal Helicopters Inc., Juneau, Alaska. The solo certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and a company flight plan was in effect. The flight originated at the Juneau International Airport, Juneau, about 1325. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on May 5, the pilot reported that she was landing on an elevated landing platform, at a remote radio repeater site. She said that after landing, as she retarded the throttle to the flight idle position, the helicopter began to shake violently, and tip backwards. She added that she opened the throttle in an attempt to restore rotor rpm, but the helicopter continued to tip backwards, and the tail rotor blades struck the ground. The helicopter sustained substantial to the tail rotor gearbox assembly, and vertical fin. According to a Federal Aviation Administration (FAA) operations inspector, Juneau Flight Standards District Office on May 5, the pilot stated to him that after she had an opportunity to think about the events surrounding the accident, she felt that she had landed the helicopter with the rear skid cross-tube over the aft edge of the elevated platform.