Incident Overview
On November 1, 2022, a Cessna TU206G, registration HK3072, operated as a non-scheduled air taxi, departed from Aeródromo El Refugio (SKNA) in La Macarena, Meta, Colombia, at 11:25 local time. The aircraft was en route to Villavicencio (SKVV) with three passengers and one pilot onboard. Shortly after takeoff from runway 35, during initial climb, the pilot observed significant fluctuations in engine RPM. Despite activating the fuel boost pump, the condition did not improve. The pilot decided to carry out a forced landing in what he considered a suitable unprepared field.
Landing and Aftermath
The pilot configured the aircraft and executed a controlled forced landing. During deceleration, the aircraft encountered uneven terrain, causing it to overturn and come to a sudden stop. The pilot and three passengers evacuated the aircraft by themselves without sustaining injuries. The accident occurred in daylight with visual meteorological conditions (VMC).
Damage Assessment
The aircraft sustained minor damage, including damage to the left wingtip fairing, the cargo pod section, the engine ventral cover, a fractured nose landing gear, and deformation of one propeller blade. No fire occurred.
Investigation Findings
The investigation was conducted by the Colombian Directorate of Technical Accident Investigation (DIACC), with participation from the NTSB (as state of design and manufacture) and technical advisors from Cessna, Continental, and Hartzell. A passenger video was analyzed by the AAIB (UK) using sound spectrum analysis.
Probable Cause
The serious incident was caused by:
- A forced landing in an unprepared field following considerable RPM fluctuation during initial climb.
- Malfunction of the propeller governor due to erroneous calibration of the propeller revolutions, resulting in deficiencies in oil pressure demand and supply to the system.
Contributing Factors
- Deficient practices and deviation from established standards during maintenance of the propeller governor, particularly an unnecessary braking of the component's adjustment screw.
- Weaknesses in supervision and quality control of maintenance services performed by the operator.
Conclusions
The investigation concluded that the propeller governor malfunction led to the RPM fluctuations, forcing the pilot to land in an unprepared field, resulting in a dynamic rollover. The maintenance errors and lack of oversight contributed to the component failure. Three safety recommendations were issued.