On July 14, 2019, about 1315 central daylight time, a Piper PA18-150, N6963B, was substantially damaged when it was involved in an accident near Osceola, Wisconsin. The commercial pilot was not injured. The glider towing flight was conducted under the provisions Title 14 Code of Federal Regulations Part 91.

The pilot reported that he had three non-eventful glider tows prior to the accident flight. On the fourth glider tow of the day, the pilot added full power for takeoff and became airborne at 55 mph indicated airspeed. About 5 to 15 feet off the ground, the pilot heard a sudden '"bang," and the nose of the airplane pitched up about 40ºand rolled right about 45º. The aircraft seemed uncontrollable with rudder. The pilot was able to get the wings level before the airplane hit the ground hard. The pilot reduced the power to idle and applied brakes. The airplane skidded between two electric poles, bounced onto a road, went through a ditch, and came to rest inverted. The empennage sustained substantial damage. The glider being towed had released the tow rope and landed uneventfully nearby.

Examination of the airplane revealed a broken attachment fitting of the right horizontal stabilizer. The Ceconite fabric covering was removed from the right and left stabilizers. The attachment corner of the right stabilizer frame was fractured. Pitting, multiple broken welds, and corrosion were found around the fracture. The right stabilizer frame had been fabricated and was not a Federal Aviation Adminstration/parts manufacturer approval-approved part.   Review of maintenance records revealed that the stabilizer assembly had been removed for inspection, refurbished, and replaced multiple times. The most recent maintenance was performed on March 1, 2019, when an annual inspection was completed and new sleeves for the forward attachment points were fabricated and installed on the stabilizer assembly.