On September 5, 2006, about 1830 mountain standard time, an Ageton MXL Sport II, N503RX, operated by its owner, experienced a total loss of engine power during initial climb from a privately owned airstrip located at the pilot's residence in Marana, Arizona. During the forced landing, the amateur built experimental airplane collided with a tree and was substantially damaged. The student pilot was seriously injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the local area personal flight that was originating. The flight was performed under the provisions of 14 CFR Part 91. The pilot verbally reported to the National Transportation Safety Board investigator that the airstrip is located in his backyard. The pilot stated that his airplane had "plenty of fuel," and it was operating normally during the start of his initial takeoff and climb out. However, without warning, all engine power was suddenly lost upon gaining between 60 and 70 feet above the ground. The pilot indicated that he tried to make a forced landing on the available runway, but the airplane impacted a tree beyond the runway. The pilot additionally reported that in August 2004, his certified flight instructor (CFI) had endorsed his student pilot certificate to solo in the accident airplane. Also, the CFI's last 90-day solo flying endorsement was written in his logbook on October 24, 2004. The student pilot stated that he had not received any flight instruction during the past 6 or 7 months. The pilot indicated that his airplane sustained considerable damage during the impact sequence, and it was a total loss. He did not anticipate attempting to fly it again. The pilot reported that he does not know why the engine lost power. As of October 4, 2006, the National Transportation Safety Board investigator has not received the required "Aircraft Accident Report," NTSB form 6120.1, from the accident pilot.