What happened
On January 9, 2016, during a routine pre-flight inspection at the Rudniki (EPRU) aerodrome, cracks were identified in the paint layer on the lower wing surfaces of an SZD-50-3 Puchacz, registration SP-3288, operated by Aeroklub Częstochowski. The cracks were specifically noted in the vicinity of the brake boxes and near a drainage hole.
Records indicated that the glider's most recent flights occurred on December 31, 2015, under ambient temperatures of approximately -15°C. During those previous flights, the crew had performed basic aerobatic maneuvers. No damage was noted during the pre-flight inspection on that December date.
The investigation
Following the discovery, the aircraft underwent a workshop inspection at the Wirkk glider service facility. Technicians removed the layers of paint and filler to examine the underlying structure. The investigation established that the cracks were confined to the paint layer and did not extend into the composite wing skin. While a potential disruption in the laminate structure was observed in one area after the paint was removed, it was determined that this was likely unrelated to the specific paint cracking event.
Findings
- The cracks in the paint on the lower wing surfaces most likely occurred during aerobatic maneuvers.
- The low ambient temperature during the previous flight operations may have contributed to the incident by reducing the elasticity of the paint.
- The investigation noted that the maximum speed for aggressive control of the SZD-50-3 Puchacz is 150 km/h, while the permissible speed is 215 km/h; therefore, pilots must maintain strict adherence to speed limits and control deflection ranges during aerobatics.
Safety action
- The incident was scheduled to be discussed at a mandatory technical conference for the Aeroklub Częstochowski, which served as a prerequisite for flight authorization for the 2016 season.