On September 11, 1999, at 1730 hours Pacific daylight time, an experimental Glover Teenie Two, N925SG, entered a spiral and crashed near the Chino, California, airport while attempting to return to the field for landing. The attempted return to airport maneuver was precipitated by a loss of engine power while in the traffic pattern. The airplane was destroyed; however, the student pilot, the sole occupant, received only minor injuries. The airplane was owned and operated by the pilot as a personal flight under the provisions of 14 CFR Part 91 when the accident occurred. The local flight originated from the Chino airport at 1720 on the evening of the accident. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The airport control tower operator stated that, after takeoff from runway 21, the pilot reported that he was "unable to reach 2,000 feet," and that he needed "to come back and land." He cleared the pilot to land on runway 26R. He next observed the airplane, which at the time was at 1,600 feet msl north of the airport, entering a tight nose down spiral. He said the airplane remained in the spiral until it disappeared from his view. The field elevation at Chino airport is 650 feet msl. A mechanic at the airport told Federal Aviation Administration (FAA) inspectors that the pilot had been experiencing engine problems that involved overheating and loss of power episodes. The tower operator recalled that during taxi, the pilot had had to restart the engine. An FAA inspector reported to the Safety Board investigator that he examined the airplane and interviewed the pilot. According to the inspector, the pilot had replaced the fixed jet in his single jet carburetor with an adjustable jet. When the inspector examined the carburetor after the accident, he noted that the jet was missing from the carburetor. A visual search of the immediate area failed to locate the missing jet. The FAA inspector also provided the airplane data that is contained in this report. According to FAA records, the pilot reported having accumulated a total of 9 hours of flight time on September 16, 1997, when he completed an application for a third-class medical certificate. At the time of the accident, the pilot told the same inspector that had flown the accident airplane exclusively since he completed its construction on July 7, 1999, a total of 44.7 hours. The pilot's student pilot certificate; however, did not show a solo endorsement for this make and model airplane. An initial Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2, was sent on September 14, 1999, along with a cover letter explaining the pilot's reporting responsibilities. The letter also contained a telephone number for the pilot to call for help or information about meeting the requirements. When the pilot failed to respond to the initial contact, a second form again with an accompanying cover letter of instructions was sent on May 17, 2000. Both envelopes were sent to the address that the pilot had reported to the FAA as his place of residence on his latest application for a medical certificate, dated November 3, 1997. Neither letter has been returned.