On April 10, 2005, about 1430 Alaska daylight time, a wheel-equipped Piper PA-18 airplane, N8960C, sustained substantial damage following a loss of control and nose over while landing at a remote, off-airport gravel bar in the Knik River, about 12 miles south-southeast of Palmer, Alaska. The private pilot/airplane owner and the sole passenger were not injured. The local, 14 CFR Part 91 personal flight operated without a flight plan in visual meteorological conditions. The flight departed Butte Muni airstrip, Palmer, about 1430. During a telephone conversation with the NTSB investigator-in-charge on April 11, the pilot related that he was practicing touch and go landings on the gravel bar. He said on the accident landing, the main landing gear encountered a depression in the gravel bar, and he was unable to maintain control of the airplane and keep it from nosing over. He noted that the airplane received structural damage to the rudder, lift struts, and fuselage, and that there were no preaccident mechanical problems with the airplane.