On April 18, 1997, at 1400 Alaska daylight time, a tundra tire equipped Piper PA-12, N92793, crashed during landing at Nikiski, Alaska. The airplane was being operated as a visual flight rules (VFR) local area instructional flight when the accident occurred. The airplane, registered to and operated by the pilot, sustained substantial damage. The solo student pilot was not injured. Visual meteorological conditions prevailed. The flight originated at Kasilof, Alaska, at 1330. A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office (FSDO), reported the airplane had previously been equipped with fixed skis. The pilot removed the skis, and replaced them with large tundra tires. The pilot was practicing takeoff and landings. He landed at Kasilof, and attempted to turn the airplane to the left in preparation for departure. The airplane was hard to turn, and the pilot got out of the airplane, and physically moved the tail around to position the airplane for takeoff. After liftoff, the pilot noticed the left wheel and tire fall off the axle. The pilot continued to his destination and landed on a private airstrip, known as McGahan Industrial Airpark, located about 1 mile southwest of Nikiski. The pilot touched down on the gravel runway, and the right main gear collapsed, folding under the wheel. The airplane received damage to the main landing gear, the right wing spar, and right wing lift struts. An inspection of the airplane by the FAA revealed the left wheel axle retaining nut was missing.