What happened
On February 8, 2012, a Cessna T-210-N, registration EC-EKV, was performing a private flight from Utrera, Spain, to Cascais, Portugal. While cruising at 5,000 feet over the Sierra de Aracena in the province of Huelva, the pilot first noticed engine instability. Although switching fuel tanks appeared to temporarily resolve the issue, the engine failure progressed significantly a few minutes later.
The pilot reported a sudden increase in oil temperature, followed by intense vibrations that affected the instrument panel, and a drop in oil pressure below minimum levels. Shortly thereafter, the engine ceased operation entirely. The pilot declared an emergency with Sevilla Control and began an emergency descent. Due to the mountainous and densely forested terrain, the pilot was unable to locate a clear landing site.
Following the flight manual procedures, the pilot configured the aircraft with full flaps and kept the landing gear retracted to minimize impact resistance. The aircraft struck several holm oaks during the descent, which slowed the plane over a distance of approximately 70 meters. The impact caused significant damage to the airframe and engine, though the passenger compartment remained intact. The flight crew included the pilot and one passenger, who sustained one serious injury and one minor injury, respectively.
The investigation
The CIAIAC investigation focused on the mechanical failure of the Continental TSIO-520-T engine. Physical examination of the engine components revealed that the failure originated within the crankshaft. Specifically, the investigation established that an oil transfer tube had displaced inside the crankshaft, which subsequently obstructed the lubrication circuit to the connecting rod bushing of cylinder number 4.
While the investigators identified the exact location of the failure, they could not determine the precise cause of the tube's displacement or the nature of the solid substance that blocked the lubrication path. The investigation also noted difficulties in obtaining follow-up laboratory results from the engine manufacturer, Continental Motors Inc., due to internal coordination issues and customs delays in the United States.
Findings
- The primary cause of the emergency landing was a total engine failure caused by the displacement of an oil transfer tube and the subsequent blockage of the lubrication path to the number 4 cylinder's connecting rod bushing.
- The pilot's decision to use full flaps and a retracted landing gear was appropriate and helped increase the chances of survival.
- The heavy tree cover in the area prevented the selection of a suitable landing site, leading to the impact with obstacles.
- There was a lack of reliable flight and maintenance records maintained by the operator and the maintenance organization (CAMO).
Safety action
- REC 27/15: Directed to Continental Motors Inc., recommending improved internal coordination and support for accident investigations involving their products, in accordance with ICAO Annex 13.
- REC 46/15: Directed to AESA (Spanish Aviation Safety Agency), recommending more effective supervision of maintenance management organizations (CAMO) to ensure the traceability and reliability of aircraft maintenance and flight activity records.