What happened
On April 11, 2015, an experimental Quad City Challenger II bearing registration N30796 crashed into a farm field near Chippewa Falls, Wisconsin. The aircraft was performing a visual pattern downwind maneuver at Rosenbaum Field Airport (3WI9) when witnesses observed the airplane enter a steep dive. The aircraft struck the ground in a nose-low attitude, creating a two-foot-deep crater, and a post-crash fire consumed much of the fuselage and tail.
The pilot sustained 1 fatal injury. At the time of the accident, the weather was characterized by visual meteorological conditions with a wind of 250 degrees at 11 knots and 10 miles of visibility.
The investigation
An examination of the aircraft's engine and airframe revealed no evidence of mechanical failures or malfunctions that would have prevented normal operation. Investigators confirmed that flight controls were continuous and the engine crankshaft was functional via propeller rotation. The wooden propeller was found fragmented at the hub.
A review of the pilot's medical records showed a history of coronary artery disease, hypertension, and diabetes. An autopsy performed by Sacred Heart Hospital determined the cause of death was blunt force injuries. The autopsy also revealed an enlarged heart, severe multi-vessel coronary artery disease with complete occlusion of two bypass vessels, evidence of a previous heart attack, and active inflammation of the heart muscle (myocarditis).
Findings
Investigators concluded that the pilot's medical condition, specifically the presence of myocarditis and severe coronary artery disease, placed him at a high risk for a cardiac arrhythmia and sudden incapacitation. Based on the autopsy findings, it was determined that the pilot most likely suffered a cardiovascular event that led to the loss of control of the aircraft.