WPR17FA074 · Quicksilver MXL II

The pilot, who did not hold a pilot or medical certificate, had been performing multiple high-speed taxi tests in the experimental amateur-built airplane since he had completed construction of it about 2 months before the accident. During those tests, the airplane had been pulling to the left. About 1 month before the accident, the pilot performed the first flight test; however, shortly after getting airborne, the airplane rolled left, departed the runway, struck a hangar, and sustained substantial damage. He spent the next month repairing the damage sustained in that accident and performing more high-speed taxi tests.

Onboard video footage revealed that, during the days leading up to the final accident, the pilot performed multiple high-speed taxi tests but was unable to maintain a straight track down the runway. On the day of the accident, he performed another erratic high-speed taxi test during which the airplane veered left and right, but, instead of stopping and attempting to determine the reason for the directional control problem, he turned the airplane around and departed in the opposite direction. Shortly after rotation, the airplane began to roll left. The pilot applied corrective control inputs (right aileron and rudder), and, although the control surfaces responded appropriately, the left turn continued. The airplane then rapidly rolled to a steep left bank, the nose dropped, and the airplane rolled over into a spin. The airplane struck the ground in a nose-down attitude, and the pilot was fatally injured.

Postaccident examination revealed that a load-carrying structural member on the forward left side of the airframe had not been properly secured when the pilot constructed the airplane. The unsecured structural member created a differential load between the left and right wing supporting structures and flying wires. This differential load was further increased as the airplane departed the runway surface, which transferred the weight of the pilot from the landing gear to the unsecured structural member. The resultant imbalance likely caused the left wing to warp, creating aerodynamic forces that could not be overcome by the flight controls.

Witness marks on the structural member indicated that the error had gone undetected since construction was completed, and it was most likely the reason for the loss of control during the first flight test about 1 month before the accident. The airplane had not been registered with the FAA and did not have an airworthiness certificate, which should have been done before a flight test. Therefore, it did not benefit from receiving an official inspection from an FAA representative, who may have caught the error.

The toxicology findings indicated that the pilot had used substantial amounts of methamphetamine in combination with hydrocodone (an impairing opioid), diazepam (an impairing benzodiazepine), THC (the active compound in marijuana), gabapentin (an impairing anti-seizure medication), and possibly alcohol before attempting flight. It could not be determined if the pilot was in the "high" phase of use and feeling grandiose and euphoric, or if he was beginning to come down from his high and feeling dysphoric and agitated at the time he elected to attempt flight. In either case, it is very likely that the pilot's judgement and decision-making were impaired by his use of methamphetamine in combination with multiple other impairing substances and that his impairment contributed to his willingness to attempt a flight in the airplane without having identified and repaired the known control problem with the airplane

Verbatim NTSB analysis and probable cause from the NTSB dataset