CEN18FA140

The flight instructor and the student pilot departed at sunset on a local flight in the airplane from a private airstrip adjacent to the flight instructor's home. About 25 minutes after takeoff, the flight instructor's sister was about 3 miles from the airstrip and observed the airplane fly over her position about 3 miles from the airstrip. She reported that the airplane was low, but nothing seemed unusual and both pilots waved to her. When the airplane did not return to the airstrip, the flight instructor's wife reported it overdue. The wreckage was located early the following morning. There were no known witnesses to the accident. Postaccident airframe and engine examinations did not reveal any anomalies consistent with a preimpact failure or malfunction. In the absence of any witnesses, or an identified preimpact failure or malfunction with respect to the airplane, the investigation was unable to determine the cause of the impact with the terrain. The student pilot's toxicology testing was positive for dextrorphan and doxylamine in liver tissue but not in cavity blood; however, the levels present were far too low to have had any significant effects.

The airplane was issued an FAA experimental, amateur-built special airworthiness certificate in August 1996. FAA records indicated that the registration was cancelled in August 2012 following a reported sale of the airplane. The necessary documentation to complete the registration process as required by the FAA had not been submitted. No additional documentation was on file with the FAA and the airplane remained unregistered at the time of the accident. An individual reported that he had owned the airplane from 2006 until early 2016. He flew the airplane once in the spring of 2007. He recalled that during that flight he encountered turbulent wind conditions and he never flew the airplane again. He had several friends that would fly it occasionally. There were no issues with the airplane at that time. He stated that the airplane was sold to the flight instructor in early 2016. He did not file any paperwork with the FAA related to either the purchase or the sale of the airplane. The flight instructor's wife stated that the student pilot purchased the airplane in early 2016. Her husband worked on the airplane re-wiring the electrical system and performing routine maintenance on the brake system. The first flight under the student pilot's ownership was on April 5, 2017; about one year after the airplane was purchased. The accident flight was the second flight since it was purchased by the student pilot. A review of the available airplane maintenance records revealed that the most recent logbook entries were dated December 2004. A bill of sale, dated December 2006, was included with the airplane records. On April 15, 2018, about 2100 central daylight time, an experimental, amateur-built David Bordiuk Challenger II Special airplane, N635DT, was substantially damaged during an in-flight collision with terrain near Friona, Texas. The flight instructor and student pilot were fatally injured. The airplane was owned by the student pilot and was being operated by the flight instructor as a Title 14 Code of Federal Regulations Part 91 instructional flight. Night visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The local flight originated from the Hefner Farms Airport (7TS9), Bovina, Texas, about 2020. The flight instructor's wife reported that the flight departed "right at sunset" from an airstrip located immediately north of their home. About 2045, the flight instructor's sister was about 3 miles north of the airstrip and observed the airplane fly over a couple of times. She noted that the airplane was low, but that nothing seemed unusual. Both the flight instructor and the student pilot waved. When the pilots did not return from the flight, the flight instructor's wife called both pilots' cellphones with no response. She checked the airstrip and the hangar/garage area, but the airplane was not there. She then contacted the local authorities to report the flight overdue. The airplane was subsequently locatedabout 0100 the following morning. There were no known witnesses to the accident. South Plains Forensic Pathology, Lubbock, Texas, performed autopsies of the flight instructor and the student pilot. Their deaths were attributed to blunt force injuries sustained in the accident. The FAA's Bioaeronautical Science Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing on specimens from the flight instructor and the student pilot. The flight instructor's toxicology testing was negative for all substances in the testing profile. The student pilot's toxicology testing was positive for dextrorphan and doxylamine in liver tissue but not in cavity blood. Doxylamine is an over-the counter, antihistamine medication that can be used in combination with decongestants and other medications to relieve sneezing, runny nose, and nasal congestion caused by the common cold and allergies. This medication could impair the mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, flying, and operating heavy machinery). Dextrorphan is a metabolite of dextromethorphan, which is a cough suppressant. The flight instructor's sister described the weather that evening as "very nice." It was clear and "not windy." Sunset occurred at 2024 on the day of the accident, with civil twilight ending at 2050. The moon set at 2011 and was in a new moon phase. The flight instructor's most recent logbook entry was dated March 31, 2018. His logbook did not include any entries related to a Challenger airplane. However, he had logged 11.1 hours in a Kolb Twinstar Mark III airplane. An entry dated April 10, 2016 included the remark, "Flight with [the student pilot] to get his Challenger." Federal Aviation Administration (FAA) records indicated that the student pilot was issued a third-class airman medical certification in February 2012, with a restriction for night flying and color signal control. The medical certificate expired for all classes on February 28, 2017. The student pilot reported no civil flight experience at the time of the application. The accident site was located in a harvested corn field about 0.4-mile northwest from the departure airstrip. The airplane came to rest upright and was oriented on a south heading. An irrigation boom was located about 400 feet north-northwest from the airplane; however, no obvious signs of impact to the boom were observed. Postaccident airframe and engine examinations were conducted by the NTSB investigator-in-charge with the assistance of a technical representative associated with the engine manufacturer. The examination did not reveal any anomalies consistent with a preimpact failure or malfunction. A detailed summary of the examination is included in the docket associated with the investigation.