On August 14, 1997, at 0730 Alaska daylight time, an American Champion 7ECA Citabria, N5507H, sustained substantial damage when it contacted terrain during takeoff from a gravel bar on the Hulahula River, about 50 miles south of Kaktovik, Alaska, at position 69-03.2 north latitude, 144-35.3 west longitude. The private certificated pilot and single passenger were uninjured. The flight was conducted under 14 CFR Part 91 as the return leg to Fairbanks, Alaska, from a sheep hunting trip. Visual meteorological conditions prevailed at the time of the accident, and an extended flight plan had been filed with two other pilots. The pilot stated that the airplane hit a rock during the start of the takeoff roll, and separated the tailwheel. He initiated rescue by turning on his Emergency Locator Transmitter, and was recovered by a helicopter from the North Slope Borough. Inspection of the airplane by an FAA inspector revealed damage to lower ribs in the rudder.