General Aviation News will often reprint accident reports from the US’s National Transportation Safety Board (NTSB) including one from August 2009 about a fatal accident involving an RV-6 in Caldwell, Idaho. According to a family member of the pilot killed in the crash, the aircraft had not been flown for about a year and had sat on the ramp.
However and a week before the fatal accident, the pilot did fly the aircraft once around the traffic pattern. Moreover and on the day of the fatal accident, the pilot had:
….removed and sandblasted the spark plugs, checked the cylinders for compression, and removed and cleaned the air filter. Some sort of foreign matter was found in the filter.
According to a witness of the accident, the aircraft had flown by him at 100 to 200 feet above ground level while making some kind of a popping noise and then it:
…made a quick left turn to a left downwind leg, and as the airplane continued on the downwind, the nose pitched up, but the airplane did not appear to be 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 destroyed by fire.
And while no anomalies were found with the engine, cylinders and valve train, all of the aircraft’s spark plugs had excessive gaps while all but one failed a bench check when they were exposed to pressure greater than 80 PSI. Moreover, no aircraft nor engine logbooks were found during the accident investigation.
Nevertheless, the pilot’s failure to maintain enough airspeed leading to a stall/spin during a maneuver in the traffic pattern was ruled as the probable cause of the fatal accident. However, the fact that the aircraft had not been flown in awhile along with the pilot’s servicing of the aircraft on the day of the accident were the most likely causes of the accident.