On August 7, 2004, about 0800 Alaska daylight time, a tundra tire-equipped Piper PA-18 airplane, N645RF, sustained substantial damage when it collided with terrain at the approach end of a remote airstrip, about 16 miles northeast of Palmer, Alaska. The airplane was being operated as a visual flight rules (VFR) local area on-demand cargo flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated by the pilot. The commercial certificated pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. The flight originated at the Wolf Lake Airport, Palmer, about 0730. No flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on August 7, the pilot reported that he was landing at an airstrip in Carpenter Creek, Alaska. The airstrip is oriented north/south, and is about 500 feet long. The pilot said he was landing toward the south and collided with the edge of the airstrip, which is also the bank of Carpenter Creek. He indicated the landing gear was torn off, and the airplane came to rest on its belly-mounted auxiliary fuel tank. The engine and propeller were damaged when the airplane nosed down on the airstrip. On August 11, after the airplane was recovered and inspected by a mechanic, the pilot notified the NTSB IIC that the airplane received structural damage to the aft gusset of the right main landing gear attach point.