What happened
On August 26, 2017, during a routine post-flight inspection at the Warsaw-Babice (EPBC) aerodrome, a glider pilot identified structural damage on the upper surface of the wings. The deformation, appearing as a wave-like distortion, was located in the vicinity of the brake boxes. Prior to this discovery, the pilot had noted cracks in the paint in the same area.
Following the discovery, the Twin Astir glider was transported to a maintenance facility for further evaluation. During the inspection, technicians determined that the structural issue was a known characteristic associated with this specific aircraft model. To rectify the issue, the damaged sections of the wing skin near the brake boxes were replaced, after which the aircraft was returned to service.
The investigation
The investigation focused on the nature of the wing deformation and the underlying cause of the surface irregularities. The examination confirmed that the structural change was not the result of an external impact or flight incident, but rather a characteristic maintenance issue related to the aircraft's construction and usage.