N797NTl Ultralight Sro STINGSPORT

On April 25, 2019, about 1249 Pacific daylight time, a TL Ultralight Sro Stingsport airplane, N797N, was destroyed when it was involved in an accident near Madera, California. The flight instructor and student pilot were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

A pilot-rated witness reported that when he departed Madera Municipal Airport (MAE), Madera, California, the accident airplane was already in the traffic pattern. After about 30-40 minutes, the witness returned to MAE and heard one of the accident pilots announce that they would perform an "emergency turn around at 500 feet." After about 10 minutes, the witness made a radio call to the accident airplane inquiring about its location but did not get a response. He then departed MAE and observed the accident airplane on the ground about 0.5 nautical miles from the departure end of runway 30. Two other witnesses at MAE listening to communications reported that the flight instructor and student pilot were conducting traffic pattern work, and all communications were standard; the last communication they heard was that the pilot would be executing a simulated emergency landing to runway 12.

Review of data obtained from a portable GPS unit found on board the accident airplane indicated that the airplane arrived at MAE at 1226:52, about 15 minutes after departing Sierra Sky Park Airport (E79), Fresno, California. The data showed that, after two landings and takeoffs, the airplane lifted off runway 30 a third time at 1248:30. At 1249:31, when the airplane was at a GPS altitude of 764 ft and a groundspeed of 64 knots, it began a 180° descending right turn back toward MAE. The final recorded data point was 16 seconds later, at 1249:47, with a reported GPS altitude of 324 ft, a derived groundspeed of 21 knots, and a track of 183°.

It could not be determined which pilot was manipulating the flight controls when the accident occurred.

Examination of the accident site revealed that the airplane impacted terrain in a nose-down attitude and came to rest upright on a heading of 167° magnetic, about 0.45 nautical miles northwest from the departure end of runway 30. The wreckage was contained to an area 30 ft wide and 18 ft long. The three-blade wooden propeller was separated at the hub. The cockpit area with the instrument panel was crushed and displaced aft. Both wings remained attached to the fuselage by their respective mounts. The hinged ailerons and split-type flaps were affixed to the aft spar of each wing. The empennage remained attached to the fuselage through the elevator control push rod and rudder control cables and was bent upwards. The vertical stabilizer, horizontal stabilizer, rudder, and elevators remained attached to the aft empennage and were undamaged. All three-landing gear remained attached to the fuselage. All flight controls were attached to the airframe, and the continuity of the flight control system from the left and right cockpit controls to all primary flight control surfaces was confirmed.

The engine was displaced aft into the firewall as result of the impact. Both carburetors were displaced from the intake manifolds. Each carburetor was disassembled and found unremarkable. The top and bottom spark plugs were removed and exhibited signatures consistent with normal operation. The gearbox was removed and examined; evidence of rotation was visible, as the propeller shaft was pushed aft into the crankcase with a corresponding mark on the crankcase. The propeller shaft was rotated by hand within the gearbox, and no anomalies were noted. Rotational continuity was established throughout the engine and valvetrain when the propeller was rotated by hand. Examination of the engine and airframe did not reveal any evidence of preexisting mechanical malfunctions.

The flight instructor’s last valid medical certificate was issued on April 2, 2007 and expired for all classes on April 30, 2009. His last medical examination was dated September 20, 2018, at which time the examiner deferred issuance to the Federal Aviation Administration (FAA), and the flight instructor was not issued a medical certificate at that time.

According to the autopsy report from the Sheriff’s Department Madera County Coroner Division, the cause of death of the flight instructor was massive blunt impact injuries. The FAA's Forensic Sciences Laboratory conducted toxicology tests on specimens from the flight instructor. The results were negative for carboxyhemoglobin and ethanol. Testing identified metoprolol, rosuvastatin, and glipizide, which are not considered impairing.

According to the autopsy report from the Sheriff’s Department Madera County Coroner Division, the cause of death of the student pilot was multiple blunt impact injuries. The FAA's Forensic Sciences Laboratory conducted toxicology tests on specimens from the student pilot. The results were negative for carboxyhemoglobin and ethanol. The testing identified 10.1 ng/mL Delta-9-THC in blood (aortic), Delta-9-THC in liver, 27.3 ng/mL 11-Hydroxy-Delta-9-THC in liver, 46 ng/mL Carboxy-Delta-9-THC in blood (aortic), and 1438 ng/mL Carboxy-Delta-9-THC in liver. The marijuana plant (Cannabis) contains chemicals called cannabinoids; tetrahydrocannabinol (THC) is the primary psychoactive cannabinoid compound. THC has mood-altering effects, including euphoria and relaxation; in addition, marijuana causes alterations in motor behavior, perception, and cognition. THC is fat soluble, so it is stored in fatty tissues and can be released back into the blood long after consumption. While the psychoactive effects may last a few hours, THC can be detected in the blood for days or weeks. Thus, blood test results do not necessarily reflect recent use and cannot be used to prove that the user was under the influence of the drug at the time of testing.