Piper PA18 N6983B accident near Osceola, Wisconsin

Probable cause

The failure of the right horizontal stabilizer during takeoff, resulting in a loss of control and forced landing. Contributing to the accident was the installation of an unapproved stabilizer frame and failure of maintenance personnel to identify deterioration of the stabilizer during routine maintenance.

NTSB analysis

Upon takeoff, the pilot heard a “bang” and could not control the airplane. The pilot was able to get the wings level before the airplane hit the ground. The airplane bounced, went through a ditch, and came to rest inverted, resulting in substantial damage to the empennage.

Examination of the airplane revealed a broken attachment fitting of the right horizontal stabilizer. The 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. Maintenance records revealed that the stabilizer assembly had been removed for inspection, refurbished, and replaced multiple times. The most recent maintenance was performed about 4 months prior to the accident, when an annual inspection was completed and new sleeves for the forward attachment points were fabricated and installed on the stabilizer assembly.

Text from the NTSB. Open the NTSB docket for CEN19LA224 for the full record.