What happened
On October 13, 2018, a training flight was conducted near Podole-Górowa, Poland, involving a Cessna C-152 aircraft registered as SP-LXX (registration withheld in source for privacy). The flight originated from Łososina Dolna aerodrome at approximately 07:00 local time. The crew consisted of a 22-year-old student pilot and a 47-year-old instructor pilot, both holding valid medical certificates. The aircraft was equipped with a Lycoming O-235-L2C engine and had valid airworthiness documentation.
The planned route included stops at Krosno (EPKR), Arłamów (EPAR), and Rzeszów (EPRZ). After pre-flight inspections and fueling, the aircraft departed from runway 040 at 08:25 LMT. Approximately 11 minutes into the flight, while descending to 2,000 feet above mean sea level, the crew experienced severe engine vibrations. The instructor pilot assumed control and attempted a return to the departure airfield.
About one minute after the onset of vibrations, the engine stopped. Attempts to restart the engine failed, though they allowed the propeller to be set in a horizontal position. Following standard emergency procedures, the fuel mixture was cut off, ignition switches were turned off, and the master switch was disengaged. The instructor pilot executed an emergency landing in a field at 08:37 LMT. The aircraft came to rest after a 120-meter skid. Both occupants exited the aircraft unharmed and contacted local authorities.
The investigation
A user-led commission investigated the incident, focusing on the engine's mechanical condition. The Lycoming O-235-L2C engine had accumulated 1,894.7 total time in service (TIS) since its last major overhaul. During the previous 100-hour inspection at 1,808.0 TIS, low compression was detected in cylinder 3. The cylinder was removed and repaired by a Part-145 organization, restoring compression to 74 psi, which was within the acceptable range of 60–80 psi. The engine had operated for 86.7 hours since this repair.
During the most recent 50-hour inspection at 1,857.9 TIS, oil and filter inspections revealed no metal particles. The engine had operated for an additional 36.8 hours without reported anomalies prior to the event. Post-accident examination of the disassembled engine revealed significant damage to the crankshaft and cylinder 3.
Findings
The investigation determined that the primary cause was the overheating and subsequent deformation of the connecting rod foot for cylinder 3. This failure originated from a worn bearing shell, likely caused by insufficient lubrication due to the previously low compression in that cylinder. The wear led to overheating, melting of the bearing, and eventual shearing of the bolts securing the connecting rod foot.
The detached connecting rod damaged the upper left section of the engine crankcase, while the remaining portion attached to the piston destroyed cylinder 3 and the lower right section of the crankcase. The oil pump was found to be functional and its operation did not contribute to the failure. The causal chain is attributed to the initial low compression in cylinder 3, which led to bearing wear, overheating, and ultimate mechanical separation.
Safety action
No safety recommendations were issued by the PKBWL for this incident.