What happened
On May 13, 2017, an experimental AS+ LTD AC 4 glider, registration N358R, crashed during an aerotow takeoff at Blair Municipal Airport in Blair, Nebraska. The flight was a local personal mission conducted under Part 9 and was being launched from a grass strip parallel to the paved runway.
As the glider began its initial climb, the canopy unexpectedly rotated open. Witnesses observed the pilot attempting to reach up and grab the canopy, which led to pilot-induced oscillations. The aircraft pitched up abruptly before pitching down, descending from approximately 20 feet above ground level. The glider struck the ground, causing the tail to separate, the wings to detach, and the fuselage to roll over. The pilot sustained 1 fatal injury due to blunt force trauma to the head.
The investigation
An investigation by the FAA examined the wreckage path, which extended 750 feet from a discarded hat to the final resting position of the fuselage. The canopy and its frame were found fractured along the wreckage path, but the latching mechanism was found to be intact. Both the forward and rear latching pins were firmly attached to the frame, and the mechanism was found to have functioned normally during post-accident testing.
Flight control continuity from the cockpit to the control surfaces was confirmed. The towline had broken free of the tow ring, but the safety link remained attached to the glider. Investigators also noted a logbook entry from May 2014 indicating a previous incident where the canopy opened during takeoff, though no maintenance records were found regarding the lubrication of the latching mechanism.