WPR15FA021 · Slingsby T67M 260

The flight instructor and student, who was receiving instruction as part of a Flight Test Engineer program, departed with the intent of completing a flight card that called for 10 maneuvers, 4 of which included spins for a certain amount of rotations. The program allowed students to fly the airplane if they felt comfortable; however, it did not require that the student fly the airplane. A camera mounted inside the airplane provided a view of the right wing. Review of the recorded video revealed that the flight performed two left spins and one right spin with uneventful recoveries before the accident sequence.

The video showed that, during the accident sequence, the airplane entered a right spin, consistent with a maneuver on the flight card, which called for a six-rotation right spin with aileron inputs before recovery. Throughout the spin sequence, little-to-no aileron input was observed. As the airplane completed about 21 revolutions, the student made an altitude call of "6,000 ft," which was the specified bailout altitude. Shortly after, a callout of "5,500 ft" was made during revolution 22, and the canopy was opened between revolutions 24 and 25. Reflections within the canopy showed the student standing while grabbing the upper canopy rail between revolutions 29 and 30 and subsequently jumping from the right wing between revolutions 33 and 34. At the time of ground impact, the airplane had completed about 34 revolutions. The delayed egress from the airplane below the specified egression altitude and just before impact likely contributed to the student's fatal injuries. Little-to-no movement of the flight instructor was observed on the video; thus it is likely he did not attempt to bailout of the airplane.

Postaccident examination of the airframe and engine revealed no evidence of any preexisting mechanical malfunctions that would have precluded normal operation. In addition, the airplane was found to be within weight-and-balance and center-of-gravity limits. Further, a recent inspection of the airplane's rigging revealed that it was within limits prior to the accident flight. The accident circumstances are consistent with the pilots' failure to recover from a spin; however, the reason for this could not be determined.

Although the flight instructor's toxicology testing detected ethanol in the kidney, the absence of ethanol in the muscle suggests the identified ethanol was likely from postmortem production rather than ingestion. Although the autopsy of the flight instructor identified left ventricular hypertrophy, which is most often associated with hypertension, age, or regular, vigorous exercise and may be associated with an increased risk for acute cardiovascular events, only mild coronary artery disease and no significant atherosclerosis were noted. However, if a cardiovascular event or loss of consciousness from any other cause (such as a seizure or neurogenic syncope) occurred in the few minutes before the flight instructor's death, it would have left no evidence on autopsy.

Verbatim NTSB analysis and probable cause from the NTSB dataset