What happened
On July 12, 2014, a pilot was participating in the 22nd Regional Glider Competitions at Michałków airfield (EPOM) in Poland. While flying a SZD-48-3 Jantar Std 3 (registration SP-3688), the pilot noticed that the aircraft was not responding precisely to control inputs. During flight maneuvers at approximately 1,500 meters, the pilot experienced significant resistance when attempting to close the air brakes and heard a metallic sound, described as an object rolling across a hard surface.
Recognizing a malfunction, the pilot decided to terminate the flight and returned to the airfield. Upon landing, ground inspections confirmed that the air brakes were difficult to operate and had partially jammed in the open position. During an attempt to force the brakes closed, a bolt pierced the aircraft's skin.
The investigation
Following the incident, the aircraft was sent to a maintenance facility for a detailed inspection. Investigators used specialized tools, including a laparoscope and cameras, to examine the internal wing structure. They discovered fragments of a bolt, a bearing, and plastic material lodged within the wing. These fragments originated from a damaged aileron pushrod guide (pass-through).
Further investigation revealed that the pushrod guides on this aircraft—and others of the same type—had been replaced with non-original, uncertified components. Historical records indicated that these modifications likely occurred in the former Soviet Union shortly after the aircraft's original purchase. The replacement parts were not compliant with the Type Certificate (TCH) for the SZD-48-3 Jantar Std 3.
Findings
- The primary cause of the incident was the failure of the aileron pushrod guide, which released debris into the wing structure. This debris subsequently blocked the aileron pushrod and the air brake control system.
- A contributing factor was the use of unauthorized, non-standard components that did not conform to the aircraft's approved design documentation.
- The investigation noted that the modified plastic components were prone to cracking and delamination, leading to the release of internal fragments.