What happened
On June 16, 2015, at approximately 13:52 UTC, a Tecnam P2002-JF, registration SP-TWY, was performing its fifth flight of the day at Łódź-Lublinek Airport (EPLL). The flight was a significant milestone, marking the student pilot's first solo operation. Following a successful approach and touchdown on runway 25L, the aircraft began its landing roll.
During the rollout, while the pilot was retracting the flaps, an audible sound resembling a tire squeal was heard. The aircraft suddenly lost directional control and veered to the right. Despite the pilot's attempts to correct the deviation using the rudder and brakes, the aircraft left the asphalt runway surface. The aircraft traveled onto the adjacent grass area, briefly rotating to the right before coming to a stop near a drainage ditch. There were no injuries to the pilot.
The investigation
The PKBWL investigation focused on the structural failure of the landing gear. The aircraft sustained damage including a deformed left flap, a bent static pressure probe, and abrasions to the underside of the left wing. The left main landing gear strut had broken away from its attachments in the fuselage.
Investigators performed a metallurgical analysis of the remains of the nut found on the forward pin of the left gear strut. Using scanning electron microscopy and chemical analysis (EDS) at the Silesian University of Technology, the team compared the failed nut to a known correct specification. The analysis confirmed that the nut was made of the correct material grade and was not an incorrect part installed during maintenance.
Findings
- The primary cause of the accident was the stripping of the threads on the nut securing the forward pin of the left main landing gear strut to the fuselage.
- A contributing factor was the accelerated wear of the aircraft, resulting from a high number of flight cycles performed for flight training in a short period of time.
- The aircraft was properly maintained, documented, and within weight and balance limits at the time of the event.
- Weather conditions were favorable (VMC) and did not contribute to the accident.