Gray RV-6 — Caldwell, ID

What happened

According to a family member of the pilot, the airplane had sat on the airport's ramp for about a year without having been flown. About a week before the accident, the pilot flew the airplane once around the traffic pattern. On the day of the accident, the pilot had removed and sandblasted the spark plugs, checked the cylinders for compression, and removed and cleaned the air filter; the filter was reported to have had "some goop" on it. A witness reported observing the airplane take off, and, as it went by him at 100 to 200 feet above ground level, he heard a "popping noise." He subsequently observed the airplane make a quick left turn to a left downwind leg, and as the airplane continued on the downwind he observed the nose increase in pitch, but it was not climbing. As the airplane came abeam the numbers, it made a steep left turn, followed by the nose dropping before it dove into the ground and erupted in flames. The airplane was consumed by a post impact fire. A post accident examination of the engine revealed no anomalies with the cylinders and valve train. All spark plugs were found to have excessive gaps, and all but one failed a bench check when exposed to pressure greater than 80 psi. A post accident examination of the airframe revealed no anomalies. No aircraft or engine logbooks were located during the investigation.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.