Amateur-built RV-7A accident near Jackson Hole, Wyoming, September 11, 2013

The NTSB's narrative final · quoted from the NTSB record

The pilot, who was also the owner/builder of the experimental kit airplane, departed for a cross-country flight from his home airport. Witnesses reported that, following departure, they observed the airplane climb to about 500 to 600 ft above ground level while it was maneuvering onto the downwind leg. Witnesses also reported that the engine was producing abnormal sounds and appeared to lose power. While on the downwind leg, the pilot declared an emergency and indicated that the engine had lost power; the air traffic controller then cleared the airplane to turn right onto the base leg and land. Witnesses reported that, as the airplane was turning from the downwind to the base leg of the traffic pattern, a wing dropped and that the wings were then nearly perpendicular to the terrain. Given the reported wind speeds, the airplane would have encountered a 13- to 20-knot tailwind on the downwind leg and up to 20-knot right crosswind gusts while on the base leg. The tailwind would have resulted in a groundspeed that was much higher than the airspeed, and the pilot likely did not recognize that the airspeed was low. The airplane subsequently made a rapid descent and impacted terrain in a nose-low attitude. Ground scar analysis and wreckage fragmentation revealed that the airplane descended in a steep 45-degree, nose-down attitude before it impacted terrain, consistent with a loss of airplane control. A postimpact examination of the engine revealed no evidence of mechanical malfunctions or failures that could have precluded normal operation. The fuel system sustained too much fragmentation to determine if any malfunctions or failures had occurred.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.