On August 2, 2009, about 1445 Pacific daylight time, a William A. Davenport DAV-EZ, experimental amateur built airplane, N7CE, sustained substantial damage following an uncontrolled descent and impact with terrain at the Santa Monica Municipal Airport (SMO), Santa Monica, California. The certificated private pilot, the sole occupant of the airplane, received serious injuries. Visual meteorological conditions prevailed for the planned local flight, which was operating in accordance with 14 Code of Federal Regulations (CFR) Part 91. A flight plan was not filed. The flight was originating at the time of the accident. In a written report submitted to the Safety Board investigator-in-charge (IIC), the pilot reported that after taking off on Runway 21 and climbing to 1,000 feet above ground level (agl), the engine began to run rough, at which time he notified the control tower of the situation and that he wanted to return to the airport and land. The pilot stated that as he made a left downwind pattern the engine began to run intermittently, followed by it quitting. The pilot reported, "I made a rapid descent while attempting to turn final. As I neared the ground the engine started running again and I made contact with the ground at about a 45-degree angle to the runway. My left wing was down and it collided with the ground. The aircraft slid from the runway off to the right, coming to rest on the taxiway on the north side of the runway." The pilot reported that the airplane's left wing and left landing gear had separated. According to the Federal Aviation Administration (FAA) aviation safety inspector who responded to the accident site, a witness reported observing the airplane depart Runway 21, followed by hearing the engine "quit." The witness stated that he observed the airplane overhead starting to turn back toward the opposite runway, then attempted to do an "S" turn over the runway and turned south. The witness reported that the airplane's engine quit approximately 4 times while trying to get back to Runway 21, but started again each time the airplane's nose was lowered back to level flight. The FAA inspector reported that an examination of the airframe and engine at the accident site revealed that the engine had remained attached to the airframe and that blade signatures were consistent with the engine being under power at the time of impact. The inspector reported that an examination of the engine revealed that the crankshaft rotated freely when turned by hand, both left and right magnetos generated spark on all ignition leads, thumb compression was felt on all cylinders, and that when the carburetor inlet was removed about 1 pint of fuel (automotive fuel) was observed. The inspector further reported that the fuel vents (head/mains LH and RH) and main wing drains were checked with air pressure and were clear of debris and open. The fuel selector was positioned to the header tank. The left and right main tanks were checked with air pressure and found intact. Both left and right fuel tank cap O-rings were observed to be worn. The inspector stated that control continuity was established throughout the airframe from the cockpit controls to all primary flight control surfaces, and that no mechanical anomalies were noted with the airplane. The pilot failed to submit a completed NTSB Form 6120.1, Pilot/Operator Aircraft Accident/Incident Report, as requested. Under the supervision of an FAA inspector, the carburetor underwent a bench flow test and subsequent tear down examination at the facilities of Volare Carburetor, Inc., of Gibsonville, North Carolina. The bench flow test revealed no discrepancies with the fuel flow curve. The internal inspection did not show any signs of debris in the fuel bowl or blocked passages in the throttle body or bowl areas of the carburetor.