On January 7, 1996, at 0834 hours Pacific standard time, a homebuilt experimental Klingberg Miniplane DSA-1, N66TD, collided with the ground following a loss of control while attempting a forced landing in a school yard at El Cajon, California. The forced landing was precipitated by a loss of engine power. The aircraft was owned and operated by the pilot and was on a personal flight. Visual meteorological conditions prevailed at the time and included calm winds. No flight plan was filed. The aircraft was destroyed in the ground collision and postcrash fire sequence. The certificated private pilot, the sole occupant, sustained fatal injuries. The flight originated at Brown Field, San Diego, California, at 0815 as a local area personal flight intended for Gillespie field in El Cajon. The pilot contacted Gillespie ATCT for a landing clearance, then cancelled the request a short time later. The pilot indicated he was going to return to Brown Field. Firefighters at a CDF fire station near the accident site were outside doing exercises. They heard and saw the airplane as it flew over their location. The firefighters said the engine was running rough, missing, and backfiring. The aircraft circled an athletic field at a nearby school twice, then began a landing approach. The witnesses said the airplane stalled in a turn and crashed nose first into the field. A fire erupted immediately, which consumed the aircraft. FAA inspectors from the San Diego Flight Standards District Office responded to the site and interviewed witnesses. One witness is an FAA certified Airframe and Powerplant mechanic who rents a hangar directly across from the accident pilot. The mechanic reported that the pilot and another mechanic worked on the magnetos, then reinstalled them in the aircraft on January 6. After reinstallation, the engine was started and it ran extremely rough, with backfiring and missing evident. The mechanic said the pilot and the other mechanic were never able to get the engine to smooth out. On the morning of the accident, the witness mechanic saw the pilot bring the airplane out of his hangar and start it. As on the day before, the engine backfired and ran very roughly. At one point the engine did smooth out somewhat; however, the mechanic reported it was still running rough. The pilot then taxied away and departed. The airframe and engine were examined by the responding FAA inspectors and their report of the examination is appended to this report. In pertinent part, the inspectors reported that the engine accessories, including both magnetoes and portions of their respective ignition harnesses, were either heavily damaged or destroyed by fire. Compression was noted in all cylinders with accessory gear and valve train continuity established. A Stromberg model NA-S2A1 carburetor was installed on the engine. The inspectors noted that the carburetor is not approved for installation on the Continental O-200 engine.