NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
Radar data recorded the airplane operating between 3,500 feet and 1,500 feet mean sea level. Two witnesses observed the airplane performing aerobatics. One witness stated that he observed the airplane perform two chandelles over the foothills north of his house, then the airplane turned south heading into an open valley. The airplane completed two aileron rolls and was halfway into a third roll when the nose pitched down, then pitched up, and the airplane rolled so that one wing was pointing down. The airplane then simultaneously rolled inverted and pitched down entering a very rapid descent into the ground. The witness stated that the engine was operating at what sounded like full power throughout the event.
On-scene examination determined that the airplane impacted the ground with the left wing down and a 30-degree nose-down pitch. The wreckage examination identified a loose, puck-like, 4.5-inch diameter portable XM-GPS antenna in the empennage tail space that houses the elevator bell crank. The antenna had a 9-mm diameter semicircular indentation witness mark that was consistent in shape and size to the end of a 9-mm diameter bolt that attaches the forward spar of the vertical stabilizer to the fuselage frame, located directly above the elevator bell crank. The antenna location and associated witness mark indicate that the unsecured antenna migrated to the tail section of the airplane and obstructed the free movement of the elevator bell crank, limiting the pilot’s ability to control the airplane in pitch. The pilot had opened a weather service account linked through the XM-GPS antenna about 1 week before the accident. The GPS unit intended for use with the XM-GPS antenna was not located with the wreckage.