What happened
On August 9, 2024, a Cessna P210N, registration OM-DKA, was performing a VFR flight from Nitra, Slovakia, to Borsk, Poland. While cruising at approximately 3,700 ft AMSL in the Ostrava TMA, the pilot heard loud metallic bangs and observed smoke emanating from the engine compartment. Although the pilot initially attempted to reach Ostrava/Mošnov Airport (LKMT), the engine power rapidly declined, and the engine became inoperable.
Realizing the aircraft could not reach the airfield, the pilot declared a MAYDAY and prepared for a forced landing. The pilot identified a suitable field near Bartošovice, avoiding trees and power lines by maneuvering to the right. The aircraft touched down on a compacted field with the landing gear and flaps extended. Upon impact, the propeller and left wing struck the ground, causing the aircraft to nose over and invert onto its back after traveling approximately 40 meters. The pilot sustained serious injuries, and the aircraft was destroyed.
The investigation
The ÚZPLN investigation focused on the mechanical failure of the engine and the circumstances of the forced landing. Investigators examined the wreckage, performed a borescope inspection of the cylinders, and conducted a fractographic analysis of the broken components. The investigation also reviewed maintenance records, including a 50-hour inspection performed approximately 20 flight hours prior to the accident, which had noted lower compression in cylinder number 2 but found no visible abnormalities during borescope inspection.
Findings
- The primary cause of the accident was an engine failure caused by the fatigue failure of an exhaust valve stem in cylinder number 2, which subsequently led to the fragmentation of the piston.
- The fragmentation of the piston caused significant internal engine damage, including damage to adjacent cylinders.
- The forced landing into terrain was a necessary action due to the loss of engine power and the inability to reach the intended airport.
- The aircraft's inversion during the landing was caused by the impact of the propeller and exhaust components with the ground, creating a pivoting moment.