HISTORY OF FLIGHTOn August 18, 2018, about 1408 mountain standard time, an experimental Olsson Pietenpol Aircamper, N88HK, was substantially damaged when it was involved in an accident near Camp Verde, Arizona. The commercial pilot and pilot-rated passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed for the flight and no flight plan had been filed. The flight originated from Montezuma Airport (19AZ), Camp Verde, Arizona, about 1400, with a stop at Cottonwood Airport, Cottonwood, Arizona, with a return to 19AZ. The airplane impacted in a ravine surrounded by desert terrain about 2.5 miles east of 19AZ. According to the pilot's wife, the purpose of the flight was to increase the pilot's confidence in a conventional landing gear airplane (tailwheel). The wife added that the passenger was a non-current flight instructor with experience in tailwheel airplanes. WRECKAGE AND IMPACT INFORMATIONThe airplane was found in hilly, uneven desert terrain surround by shrub brush and trees. During an on-scene investigation, the first identified point of impact was a 12-inch by 4-inch depression adjacent to the tailwheel. The debris field was contained within about a 10-foot radius of the main wreckage. The main wreckage was comprised of all major airframe components and was oriented on a magnetic heading of 78°. The wing assembly was deformed in the middle section with the left portion of the wing pushed up and over the main spar, the right wing was pushed down. The airplane remained intact; both wood propeller blade roots remained attached to the propeller hub, which remained attached to the crankshaft and engine. The engine remained attached to the airframe. Flight control continuity was established. MEDICAL AND PATHOLOGICAL INFORMATIONThe Yavapai County Medical Examiner, Prescott Valley, Arizona performed an autopsy of the pilot. The pilot’s cause of death was blunt force trauma. The FAA’s Forensic Sciences Laboratory performed toxicology on the pilot’s tissue samples, which revealed Fexofenadine, a non-sedating antihistamine was detected in blood and urine. Ranitidine used to prevent and treat symptoms of heartburn was found in urine. TESTS AND RESEARCHPostaccident engine examination revealed carbon buildup on the cylinder barrels and piston faces, as well as worn spark plugs. There were no other mechanical anomalies that would have precluded normal operation. The airplanes’ two Bendix SF4R-8 magnetos were examined, and both passed the functionality bench test.