What happened
On September 26, 2017, a private TL 2000 Sting, registration OK-JUA, was conducting a VFR flight from Łososina (EPNL) to Nowy Targ (EPNT). The aircraft was carrying a pilot and one passenger. While flying near Kamienica at an altitude of approximately 3,500 feet, the pilot experienced a sudden increase in engine temperature accompanied by a loss of power. Despite attempts to manage the situation by adjusting propeller pitch and engine RPM, cylinder and oil temperatures continued to rise significantly, reaching approximately 170°C and 150°C, respectively.
Unable to continue the flight, the pilot initiated an emergency landing in a field near Wola Piskulina. The landing site was a meadow with a 16% slope and soft, uneven terrain. During the initial impact, the left main landing gear broke away. The aircraft then bounced to a height of about 2 meters and traveled an additional 20 meters. Upon the second impact, the nose gear was also lost, causing the aircraft to pitch forward. The propeller blades struck the ground, and the engine cowlings were damaged. Both occupants exited the aircraft without injuries.
The investigation
The investigation examined the mechanical state of the Rotax 912 ULS engine and the circumstances of the landing. Because the engine is an uncertified unit, the commission did not perform a direct laboratory analysis; however, the owner submitted the engine to an authorized Rotax service in the Czech Republic. The inspection revealed low coolant levels and the seizure of two cylinders and pistons. The investigation also reviewed the pilot's qualifications, the aircraft's maintenance logs, and the meteorological conditions at the time of the event.
Findings
- The primary cause of the engine failure was a thermostat blockage, which led to overheating and subsequent engine seizure.
- The overheating likely caused coolant to boil and escape through the expansion tank pressure cap.
- The severity of the aircraft damage was exacerbated by a hard landing on uneven, sloping terrain.
- The pilot was fully qualified and the aircraft's technical documentation and maintenance were in order.
- Weather conditions were favorable and did not contribute to the accident.