HISTORY OF FLIGHTOn April 11, 2015, at 1132 central daylight time, an experimental Quad City Challenger II airplane, formerly registered as N30796, impacted terrain while on visual pattern downwind at the Rosenbaum Field Airport (3WI9), near Chippewa Falls, Wisconsin. The airplane was substantially damaged and the pilot sustained fatal injuries. The airplane, with an expired registry, was operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions prevailed for the local flight, which departed without a flight plan at an unknown time. Several witnesses observed the airplane making a turn near the mid-field downwind position at 3WI9. The airplane subsequently began a steep dive, which continued until ground impact. The airplane caught fire following ground impact. PERSONNEL INFORMATIONThe pilot, age 77, held a recreational pilot certificate with airplane single engine land rating and a repairman experimental aircraft builder certificate. The pilot's logbook indicated he had flown 416 total hours as of May 5, 2006, with nearly all of his flight time accomplished in the accident airplane. Recent logbooks were not available for the investigation. According to his wife, the pilot had flown a few times over the past 12 months. The pilot's most recent Federal Aviation Administration (FAA) medical certification exam, dated May 10, 2004, did not identify any abnormal findings and the examiner issued a third-class medical certificate with the following limitation: must wear lenses for distant - possess glasses for near vision. This medical certificate expired for all classes on May 31, 2006. AIRCRAFT INFORMATIONThe airplane was a two-seat tandem, high-wing, pusher configuration. FAA records indicated the pilot manufactured the airplane and received a special airworthiness certificate on May 17, 2002. The airplane was equipped with a Rotax 503 engine and a Tennessee, Inc. wooden propeller. Maintenance logbooks were not available to the investigation. METEOROLOGICAL INFORMATIONAt 1156, the weather observation station at Chippewa Valley Regional Airport (EAU), Eau Claire, Wisconsin, located about 9 miles southwest of the accident site, reported the following conditions: wind 250 degrees at 11 knots, with gusts to 17 knots, 10 miles visibility, clear skies, temperature 15 degrees C, dew point 1 degree C, altimeter setting 30.14 inches of mercury. AIRPORT INFORMATIONThe airplane was a two-seat tandem, high-wing, pusher configuration. FAA records indicated the pilot manufactured the airplane and received a special airworthiness certificate on May 17, 2002. The airplane was equipped with a Rotax 503 engine and a Tennessee, Inc. wooden propeller. Maintenance logbooks were not available to the investigation. WRECKAGE AND IMPACT INFORMATIONThe accident site was located in a level, open farm field located about ½ mile to the east of the runway. The airplane impacted the field with a nose low attitude, which created a 2 ft deep crater, and came to rest about 40 ft from the initial impact point. A post-crash fire consumed much of the fuselage and tail. FAA examination of the airplane confirmed flight control continuity to all flight controls and engine crankshaft continuity was confirmed via rotation of the propeller. The wooden propeller was fragmented down to its hub. Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. MEDICAL AND PATHOLOGICAL INFORMATIONA review of primary care and cardiology records from January 2012 until April 2015 revealed the pilot had a history of coronary artery disease treated with multi-vessel bypass surgery, high blood pressure, elevated cholesterol, and hypothyroidism. He also had diet controlled type 2 diabetes with peripheral neuropathy resulting in difficulty with balance and walking, as well as major depressive disorder with mild symptoms controlled with fluoxetine. The pilot's latest cardiologist evaluation on October 6, 2014 documented that the pilot was stable from a cardiac standpoint and remained asymptomatic. The cardiologist documented that the pilot was not following a proper cardiac diet. The records did not document a recent exercise stress test or electrocardiogram. During his last primary care appointment, which occurred two days prior to the accident, the pilot's height and weight measured 70 inches and 251 pounds. The primary care physician documented that the pilot had no chest pain or discomfort and no shortness of breath and his high blood pressure was "well controlled". The pilot's medications included atenolol and lisinopril (medications to control blood pressure), levothyroxine (a thyroid replacement medication), fluoxetine (an antidepressant medication), atorvastatin (a cholesterol lowering medicine), tamsulosin (a medication to treat enlarged prostate), naproxen (medication to control pain and swelling), and aspirin (medication used to control pain, inflammation and fever also used to decrease the risk of recurrent heart attacks). According to his wife, the pilot underwent heart bypass surgery in September 2008. Two months prior to the accident, the pilot had been sick with upper respiratory issues and a sinus infection and he had taken a while to recover. She stated the pilot was just starting to feel well and energetic the week of the accident. On April 14, 2015, an autopsy was performed on the pilot by the Sacred Heart Hospital in Eau Claire, Wisconsin. The cause of death was blunt force injuries. The autopsy identified an enlarged heart, severe multi-vessel coronary artery disease (greater than 80 percent occlusion of all vessels) with coronary artery bypass grafts and complete occlusion of two bypass vessels, evidence of an old heart attack with scarring of the ventricular septum and active inflammation of heart muscle of the anterolateral wall of the left ventricle. The FAA's Civil Aeromedical Institute in Oklahoma City, Oklahoma performed toxicology tests on the pilot. Toxicology did not identify carbon monoxide or ethanol in cavity blood. Testing detected atenolol in liver and cavity blood, atorvastatin in liver, fluoxetine in cavity blood and liver, and its metabolite norfluoxetine in cavity blood and liver.