What happened
On July 23, 2016, a Cessna TU206G, registration HK2787, was conducting a non-scheduled passenger flight from La Macarena to Villavicencio. While cruising at 5,500 feet, the pilot experienced engine vibrations accompanied by a drop in manifold pressure and a reduction in power to 1000 RPM.
In response to the engine instability, the pilot initiated a preventive descent toward the San Martín airfield. However, during the final approach, the engine suffered a complete failure. Unable to reach the runway, the pilot attempted an emergency landing in an unprepared field at Hacienda Planadas. During the maneuver, the pilot increased the aircraft's pitch to clear a fence, which caused the aircraft to enter a stall at a very low altitude. The aircraft struck the ground with high vertical velocity and bounced twice before coming to a stop. The impact resulted in severe and minor injuries to the six occupants and caused substantial structural damage to the airframe.
The investigation
The GRIAA investigation focused on the mechanical state of the Continental TSIO-520-M engine and the sequence of the landing maneuver. Investigators performed a bench test of the engine, which revealed that while the internal mechanical components were functional, the fuel pump was operating outside of prescribed tolerances. Specifically, the investigation found that the fuel pump was poorly calibrated and suffered from internal vane wear, leading to fluctuating fuel pressure and the eventual engine flameout.
Findings
- The primary cause of the engine failure was a malfunctioning fuel pump operating outside of design tolerances, which caused fluctuating system pressure and eventual engine shutdown.
- The pilot executed an emergency landing in an unprepared field following the total loss of engine power.
- A loss of lift occurred when the pilot attempted to clear an obstacle (a fence) during the landing, leading to a high sink rate and a heavy impact with the terrain.