What happened
On July 11, 2012, a Cessna 152, registration HK2090G, was conducting a dual-instruction flight near Alvarado, Tolima, when the engine suffered a sudden and total failure. While cruising at 3,500 feet, the flight instructor reported intense vibrations and rattling, followed by the complete cessation of engine power.
The crew attempted several engine restart procedures without success and declared an emergency. Seeking the nearest available landing site, the instructor opted for the Calicanto airstrip. During the approach, the aircraft encountered a tailwind that prevented it from settling on the planned portion of the runway. As the aircraft reached the end of the runway, the pilot observed a perimeter fence ahead. In an attempt to clear the obstacle, the pilot increased pitch, causing the aircraft to enter a stall. The aircraft subsequently impacted a nearby rice field, where it flipped onto its back (capsized).
The investigation
The GRIAA investigation focused on the mechanical failure of the Lycoming O-235 engine and the accuracy of maintenance records. Physical inspection of the engine revealed that the connecting rod bolt of cylinder No. 3 had fractured due to fatigue. This failure caused the connecting rod to detach from the crankshaft, leading to secondary damage, including the breakage of the engine crankcase and the destruction of the engine's internal components.
Investigators also performed a comprehensive audit of the aircraft's flight logs. They discovered significant discrepancies in the accumulated hour totals, noting that several logbook entries were incorrectly summed or missing total flight time data. This audit revealed that the engine had been operated far beyond its manufacturer-recommended overhaul interval.
Findings
- The primary cause of the incident was a total engine failure caused by the fatigue fracture of the cylinder No. 3 connecting rod bolt.
- The engine had exceeded its Time Between Overhaul (TBO) by approximately 578 hours, having reached 2,901 hours of operation despite a 2,400-hour limit.
- Inaccurate record-keeping in the aircraft logbooks contributed to the failure to identify that the engine was overdue for major maintenance.
- The aircraft sustained significant damage, including a bent nose gear, broken engine mounting, and a damaged vertical stabilizer.
- Both the instructor and the student pilot were uninjured and able to evacuate the inverted aircraft on their own.